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Prof. Meenesh Singh
Department of Chemical Engineering, University of Illinois at Chicago, Chicago, 60607, USA

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0 Environmental Engineering
0 artificial photosynthesis
0 Carbon capture and sequestration
0 Solar-energy conversion
0 Computational materials

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artificial photosynthesis
Carbon capture and sequestration

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Paper
Published: 26 May 2021 in Lab on a Chip
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An advanced continuous-flow microfluidic device for rapid, parallel screening of crystalline materials, which can profoundly impact the discovery and development of active pharmaceutical ingredients and other crystalline materials.

ACS Style

Paria Coliaie; Manish S. Kelkar; Marianne Langston; Chengxiang Liu; Neda Nazemifard; Daniel Patience; Dimitri Skliar; Nandkishor K. Nere; Meenesh R. Singh. Advanced continuous-flow microfluidic device for parallel screening of crystal polymorphs, morphology, and kinetics at controlled supersaturation. Lab on a Chip 2021, 21, 2333 -2342.

AMA Style

Paria Coliaie, Manish S. Kelkar, Marianne Langston, Chengxiang Liu, Neda Nazemifard, Daniel Patience, Dimitri Skliar, Nandkishor K. Nere, Meenesh R. Singh. Advanced continuous-flow microfluidic device for parallel screening of crystal polymorphs, morphology, and kinetics at controlled supersaturation. Lab on a Chip. 2021; 21 (12):2333-2342.

Chicago/Turabian Style

Paria Coliaie; Manish S. Kelkar; Marianne Langston; Chengxiang Liu; Neda Nazemifard; Daniel Patience; Dimitri Skliar; Nandkishor K. Nere; Meenesh R. Singh. 2021. "Advanced continuous-flow microfluidic device for parallel screening of crystal polymorphs, morphology, and kinetics at controlled supersaturation." Lab on a Chip 21, no. 12: 2333-2342.

Journal article
Published: 17 February 2021 in Proceedings of the National Academy of Sciences
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Electrochemical oxidation of CH4 is known to be inefficient in aqueous electrolytes. The lower activity of methane oxidation reaction (MOR) is primarily attributed to the dominant oxygen evolution reaction (OER) and the higher barrier for CH4 activation on transition metal oxides (TMOs). However, a satisfactory explanation for the origins of such lower activity of MOR on TMOs, along with the enabling strategies to partially oxidize CH4 to CH3OH, have not been developed yet. We report here the activation of CH4 is governed by a previously unrecognized consequence of electrostatic (or Madelung) potential of metal atom in TMOs. The measured binding energies of CH4 on 12 different TMOs scale linearly with the Madelung potentials of the metal in the TMOs. The MOR active TMOs are the ones with higher CH4 binding energy and lower Madelung potential. Out of 12 TMOs studied here, only TiO2, IrO2, PbO2, and PtO2 are active for MOR, where the stable active site is the O on top of the metal in TMOs. The reaction pathway for MOR proceeds primarily through *CH x intermediates at lower potentials and through *CH3OH intermediates at higher potentials. The key MOR intermediate *CH3OH is identified on TiO2 under operando conditions at higher potential using transient open-circuit potential measurement. To minimize the overoxidation of *CH3OH, a bimetallic Cu2O3 on TiO2 catalysts is developed, in which Cu reduces the barrier for the reaction of *CH3 and *OH and facilitates the desorption of *CH3OH. The highest faradaic efficiency of 6% is obtained using Cu-Ti bimetallic TMO.

ACS Style

Aditya Prajapati; Brianna A. Collins; Jason D. Goodpaster; Meenesh R. Singh. Fundamental insight into electrochemical oxidation of methane towards methanol on transition metal oxides. Proceedings of the National Academy of Sciences 2021, 118, 1 .

AMA Style

Aditya Prajapati, Brianna A. Collins, Jason D. Goodpaster, Meenesh R. Singh. Fundamental insight into electrochemical oxidation of methane towards methanol on transition metal oxides. Proceedings of the National Academy of Sciences. 2021; 118 (8):1.

Chicago/Turabian Style

Aditya Prajapati; Brianna A. Collins; Jason D. Goodpaster; Meenesh R. Singh. 2021. "Fundamental insight into electrochemical oxidation of methane towards methanol on transition metal oxides." Proceedings of the National Academy of Sciences 118, no. 8: 1.

Research article
Published: 25 November 2020 in ACS Catalysis
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The electrochemical reduction of N2 to produce NH3 at ambient conditions is an effective and sustainable route to store and carry hydrogen, balance the nitrogen cycle, and provide means to produce on-demand fertilizers. The efficient electrosynthesis of NH3 is challenging because of the lower activation of N2 and higher activity toward the hydrogen evolution reaction (HER). Here, we propose theory-guided activity descriptors to identify an efficient N2 reduction reaction (NRR) catalyst, followed by its implementation in a flow-through gas diffusion electrode (GDE) to quantify the effects of pH, cation identity, H2O saturation, and N2 concentration on the kinetics of the NRR. The identified Cu catalyst with dominant (111) facets electrodeposited on a carbon paper provides optimal active sites to obtain maximum NH3 faradaic efficiency (FE) of 18 ± 3% at −0.3 V vs RHE and the maximum NH3 current density of 0.25 ± 0.03 mA cm–2 (0.86 nmol·cm–2·s–1) at −0.5 V vs RHE in alkaline medium. The electrolyte pH mostly affects the HER by pH-induced binding of *H and reorganization of H2O, which favor the NRR at an optimal pH of 13.5. Increasing the size of monovalent cations stabilizes NRR intermediates and increases the NH3 current density from Li+ to K+. However, increasing the size of the cation from K+ to Rb+ reduces the FE of NRR, which is due to a direct reduction of H2O in the solvation shell of larger cations to produce H2. Another strategy to improve NH3 FE is to reduce the H2O saturation on the catalyst, which can be achieved by sparging the reactant gas directly through the GDE. Increasing the N2(g) flow rate not only increases the gas–liquid mass transfer coefficient but also reduces the H2O saturation in the pores of the GDE, which primarily suppresses the HER. The fixed potential DFT calculations reveal an associative distal mechanism for the NRR over Cu(111), where the hydrogenation of *N2 is the rate-limiting step. This finding also corroborates with the measured reaction order with respect to N2.

ACS Style

Nishithan C. Kani; Aditya Prajapati; Brianna A. Collins; Jason D. Goodpaster; Meenesh R. Singh. Competing Effects of pH, Cation Identity, H2O Saturation, and N2 Concentration on the Activity and Selectivity of Electrochemical Reduction of N2 to NH3 on Electrodeposited Cu at Ambient Conditions. ACS Catalysis 2020, 10, 14592 -14603.

AMA Style

Nishithan C. Kani, Aditya Prajapati, Brianna A. Collins, Jason D. Goodpaster, Meenesh R. Singh. Competing Effects of pH, Cation Identity, H2O Saturation, and N2 Concentration on the Activity and Selectivity of Electrochemical Reduction of N2 to NH3 on Electrodeposited Cu at Ambient Conditions. ACS Catalysis. 2020; 10 (24):14592-14603.

Chicago/Turabian Style

Nishithan C. Kani; Aditya Prajapati; Brianna A. Collins; Jason D. Goodpaster; Meenesh R. Singh. 2020. "Competing Effects of pH, Cation Identity, H2O Saturation, and N2 Concentration on the Activity and Selectivity of Electrochemical Reduction of N2 to NH3 on Electrodeposited Cu at Ambient Conditions." ACS Catalysis 10, no. 24: 14592-14603.

Journal article
Published: 17 November 2020 in Proceedings of the National Academy of Sciences
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Magnetophoresis is an important physical process with application to drug delivery, biomedical imaging, separation, and mixing. Other than empirically, little is known about how the magnetic field and magnetic properties of a solution affect the flux of magnetic particles. A comprehensive explanation of these effects on the transport of magnetic particles has not been developed yet. Here we formulate a consistent, constitutive equation for the magnetophoretic flux of magnetic nanoparticles suspended in a medium exposed to a stationary magnetic field. The constitutive relationship accounts for contributions from magnetic diffusion, magnetic convection, residual magnetization, and electromagnetic drift. We discovered that the key physical properties governing the magnetophoresis are magnetic diffusion coefficient, magnetic velocity, and activity coefficient, which depend on relative magnetic energy and the molar magnetic susceptibility of particles. The constitutive equation also reveals previously unknown ballistic and diffusive limits for magnetophoresis wherein the paramagnetic particles either aggregate near the magnet or diffusive away from the magnet, respectively. In the diffusive limit, the particle concentration is linearly proportional to the relative magnetic energy of the suspension of paramagnetic particles. The region of the localization of paramagnetic particles near the magnet decreases with increasing the strength of the magnet. The dynamic accumulation of nanoparticles, measured as the thickness of the nanoparticle aggregate, near the magnet compares well with the theoretical prediction. The effect of convective mixing on the rate of magnetophoresis is also discussed for the magnetic targeting applications.

ACS Style

Ayankola O. Ayansiji; Anish V. Dighe; Andreas A. Linninger; Meenesh R. Singh. Constitutive relationship and governing physical properties for magnetophoresis. Proceedings of the National Academy of Sciences 2020, 117, 30208 -30214.

AMA Style

Ayankola O. Ayansiji, Anish V. Dighe, Andreas A. Linninger, Meenesh R. Singh. Constitutive relationship and governing physical properties for magnetophoresis. Proceedings of the National Academy of Sciences. 2020; 117 (48):30208-30214.

Chicago/Turabian Style

Ayankola O. Ayansiji; Anish V. Dighe; Andreas A. Linninger; Meenesh R. Singh. 2020. "Constitutive relationship and governing physical properties for magnetophoresis." Proceedings of the National Academy of Sciences 117, no. 48: 30208-30214.

Research article
Published: 03 August 2020 in ACS Applied Materials & Interfaces
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Interfacing two-dimensional graphene oxide (2D GO) platelets with one-dimensional zinc oxide nanorods (1D ZnO) would create mixed-dimensional heterostructures suitable for modern optoelectronic devices. However, there remains a lack in understanding of interfacial chemistry and wettability in GO-coated-ZnO nanorod heterostructures. Here, we propose a hydroxyl-based dissociation-exchange mechanism to understand interfacial interactions responsible for GO adsorption onto ZnO nanorod hydrophobic substrates. The proposed mechanism initiated from mixing GO suspension with various organics would allow us to overcome the poor wettability (θ ~ 140.5°) of the super-hydrophobic ZnO nanorods to the drop-casted GO. The addition of different classes of organics into the relatively high pH GO suspension with a volumetric ratio of 1:3 (organic-to-GO) is believed to introduce free radicals (-OH and -COOH), which consequently result in enhancing adhesion (chemisorption) between ZnO nanorods and GO platelets. The wettability study shows as high as 75% reduction in contact angle (θ = 35.5°) when the GO suspension is mixed with alcohols (e.g. ethanol) prior to interfacing with ZnO nanorods. The interfacial chemistry developed here brings forth a scalable tool for designing graphene-coated-ZnO heterojunctions for photovoltaics, photocatalysis, biosensors, and UV detectors.

ACS Style

Pavan S. Emani; Hisham A. Maddah; Arjun Rangoonwala; Songwei Che; Aditya Prajapati; Meenesh R. Singh; Dieter M. Gruen; Vikas Berry; Sanjay K. Behura. Organophilicity of Graphene Oxide for Enhanced Wettability of ZnO Nanorods. ACS Applied Materials & Interfaces 2020, 12, 1 .

AMA Style

Pavan S. Emani, Hisham A. Maddah, Arjun Rangoonwala, Songwei Che, Aditya Prajapati, Meenesh R. Singh, Dieter M. Gruen, Vikas Berry, Sanjay K. Behura. Organophilicity of Graphene Oxide for Enhanced Wettability of ZnO Nanorods. ACS Applied Materials & Interfaces. 2020; 12 (35):1.

Chicago/Turabian Style

Pavan S. Emani; Hisham A. Maddah; Arjun Rangoonwala; Songwei Che; Aditya Prajapati; Meenesh R. Singh; Dieter M. Gruen; Vikas Berry; Sanjay K. Behura. 2020. "Organophilicity of Graphene Oxide for Enhanced Wettability of ZnO Nanorods." ACS Applied Materials & Interfaces 12, no. 35: 1.

Research article
Published: 11 November 2019 in Proceedings of the National Academy of Sciences
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Solution crystallization is a common technique to grow advanced, functional crystalline materials. Supersaturation, temperature, and solvent composition are known to influence the growth rates and thereby properties of crystalline materials; however, a satisfactory explanation of how these factors affect the activation barrier for growth rates has not been developed. We report here that these effects can be attributed to a previously unrecognized consequence of solvent fluctuations in the solvation shell of solute molecules attaching to the crystal surface. With increasing supersaturation, the average hydration number of the glutamic acid molecule decreases and can reach an asymptotic limit corresponding to the number of adsorption sites on the molecule. The hydration number of the glutamic acid molecule also fluctuates due to the rapid exchange of solvent in the solvation shell and local variation in the supersaturation. These rapid fluctuations allow quasi-equilibrium between fully solvated and partially desolvated states of molecules, which can be used to construct a double-well potential and thereby to identify the transition state and the required activation barrier. The partially desolvated molecules are not stable and can attach spontaneously to the crystal surface. The activation barrier versus hydration number follows the Evans–Polanyi relation. The predicted absolute growth rates of the α-glutamic acid crystal at lower supersaturations are in reasonable agreement with the experimental observations.

ACS Style

Anish V. Dighe; Meenesh R. Singh. Solvent fluctuations in the solvation shell determine the activation barrier for crystal growth rates. Proceedings of the National Academy of Sciences 2019, 116, 23954 -23959.

AMA Style

Anish V. Dighe, Meenesh R. Singh. Solvent fluctuations in the solvation shell determine the activation barrier for crystal growth rates. Proceedings of the National Academy of Sciences. 2019; 116 (48):23954-23959.

Chicago/Turabian Style

Anish V. Dighe; Meenesh R. Singh. 2019. "Solvent fluctuations in the solvation shell determine the activation barrier for crystal growth rates." Proceedings of the National Academy of Sciences 116, no. 48: 23954-23959.

Journal article
Published: 09 August 2019 in Processes
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Metal–organic frameworks (MOFs) are the porous, crystalline structures made of metal–ligands and organic linkers that have applications in gas storage, gas separation, and catalysis. Several experimental and computational tools have been developed over the past decade to investigate the performance of MOFs for such applications. However, the experimental synthesis of MOFs is still empirical and requires trial and error to produce desired structures, which is due to a limited understanding of the mechanism and factors affecting the crystallization of MOFs. Here, we show for the first time a comprehensive kinetic model coupled with population balance model to elucidate the mechanism of MOF synthesis and to estimate size distribution of MOFs growing in a solution of metal–ligand and organic linker. The oligomerization reactions involving metal–ligand and organic linker produce secondary building units (SBUs), which then aggregate slowly to yield MOFs. The formation of secondary building units (SBUs) and their evolution into MOFs are modeled using detailed kinetic rate equations and population balance equations, respectively. The effect of rate constants, aggregation frequency, the concentration of organic linkers, and concurrent crystallization of organic linkers are studied on the dynamics of SBU and MOF formation. The results qualitatively explain the longer timescales involved in the synthesis of MOF. The fundamental insights gained from modeling and simulation analysis can be used to optimize the operating conditions for a higher yield of MOF crystals.

ACS Style

Anish V. Dighe; Roshan Y. Nemade; Meenesh R. Singh. Modeling and Simulation of Crystallization of Metal–Organic Frameworks. Processes 2019, 7, 527 .

AMA Style

Anish V. Dighe, Roshan Y. Nemade, Meenesh R. Singh. Modeling and Simulation of Crystallization of Metal–Organic Frameworks. Processes. 2019; 7 (8):527.

Chicago/Turabian Style

Anish V. Dighe; Roshan Y. Nemade; Meenesh R. Singh. 2019. "Modeling and Simulation of Crystallization of Metal–Organic Frameworks." Processes 7, no. 8: 527.

Research article
Published: 27 June 2019 in ACS Applied Energy Materials
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The CO2 utilization efficiency of three types of electrochemical CO2 reduction (CO2R) reactors using different ion-selective membranes, including anion exchange membrane (AEM), cation exchange membrane (CEM), and bipolar membrane (BPM), was studied quantitively via both experimental and simulation methods. The operating current density of the CO2R reactors was chosen to be between 10 – 50 mA cm-2 to be relevant for solar-fuel devices with relatively low photon flux from sunlight. In the AEM based CO2R reactor with a 6-electron per carbon CO2R at the cathode surface, an upper limit of 14.4% for the CO2 utilization efficiency was revealed by modeling and validated by experimental measurements in CO2 saturated aqueous electrolytes without any buffer electrolyte. Improvements in CO2 utilization efficiency were observed when additional buffer electrolyte was added into the aqueous solution, especially in solutions with low bicarbonate concentrations. The effects of the feed rate of the input CO2 stream, the Faradaic Efficiency (FE) and the participating electron numbers of the cathode reaction on the CO2 utilization efficiency was also studied in the AEM based CO2R reactor. The CEM based CO2R reactor exhibited low CO2 utilization efficiency with re-circulation between the catholyte and the anolyte, and was unsustainable due to the cation depletion from the anolyte without any re-circulation. The BPM based CO2R reactor operated continuously without a significant increase in the cell voltage and exhibited significantly higher CO2 utilization efficiency, up to 61.4%, as compared to the AEM based CO2R reactors. Diffusive CO2 loss across the BPM resulted in relatively low CO2 utilization efficiency at low operating current densities. Modeling and simulation also provided target BPM properties for higher CO2 utilization efficiency and efficient cell operation.

ACS Style

Meng Lin; Lihao Han; Meenesh R. Singh; Chengxiang Xiang. An Experimental- and Simulation-Based Evaluation of the CO2 Utilization Efficiency of Aqueous-Based Electrochemical CO2 Reduction Reactors with Ion-Selective Membranes. ACS Applied Energy Materials 2019, 2, 5843 -5850.

AMA Style

Meng Lin, Lihao Han, Meenesh R. Singh, Chengxiang Xiang. An Experimental- and Simulation-Based Evaluation of the CO2 Utilization Efficiency of Aqueous-Based Electrochemical CO2 Reduction Reactors with Ion-Selective Membranes. ACS Applied Energy Materials. 2019; 2 (8):5843-5850.

Chicago/Turabian Style

Meng Lin; Lihao Han; Meenesh R. Singh; Chengxiang Xiang. 2019. "An Experimental- and Simulation-Based Evaluation of the CO2 Utilization Efficiency of Aqueous-Based Electrochemical CO2 Reduction Reactors with Ion-Selective Membranes." ACS Applied Energy Materials 2, no. 8: 5843-5850.

Paper
Published: 21 June 2019 in Lab on a Chip
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While the conventional screening techniques suffer from depletion of supersaturation, the continuous-flow microfluidic device screens crystalline materials at controlled supersaturation.

ACS Style

Paria Coliaie; Manish S. Kelkar; Nandkishor K. Nere; Meenesh R. Singh. Continuous-flow, well-mixed, microfluidic crystallization device for screening of polymorphs, morphology, and crystallization kinetics at controlled supersaturation. Lab on a Chip 2019, 19, 2373 -2382.

AMA Style

Paria Coliaie, Manish S. Kelkar, Nandkishor K. Nere, Meenesh R. Singh. Continuous-flow, well-mixed, microfluidic crystallization device for screening of polymorphs, morphology, and crystallization kinetics at controlled supersaturation. Lab on a Chip. 2019; 19 (14):2373-2382.

Chicago/Turabian Style

Paria Coliaie; Manish S. Kelkar; Nandkishor K. Nere; Meenesh R. Singh. 2019. "Continuous-flow, well-mixed, microfluidic crystallization device for screening of polymorphs, morphology, and crystallization kinetics at controlled supersaturation." Lab on a Chip 19, no. 14: 2373-2382.

Research article
Published: 05 February 2019 in ACS Sustainable Chemistry & Engineering
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Sustainable and continuous operation of artificial photosynthetic (AP) system requires a constant supply of CO2 captured from the dilute sources such as the flue gas and the air to make fuels and chemicals. Although the architecture of AP systems resembles that of the natural leaves, they lack an important component like stomata to capture CO2 directly from the dilute sources. Here we design and evaluate the solar-to-fuel (STF) efficiency of the integrated AP system that captures CO2 directly from the air/flue gas and converts it to fuels using sunlight. The thermodynamic limit to the STF efficiency of such integrated AP system range from 34% - 40% for various products such as CO, HCOOH, CH4, CH3OH, C2H4, and C2H5OH using ideal multijunction light absorbers and reversible carbon capture process. The performance limits of real, integrated AP systems are obtained here for two different integration schemes such as integrated cascade systems and fully integrated systems that use technology-ready materials and components. The fully integrated AP systems can be > 66% more efficient than the integrated cascade systems as they do not need additional energy for compression, separation, and recycling of CO2. While the integrated cascade systems show highest STF efficiency with the adsorption-based carbon capture process, the fully integrated AP systems are only compatible with the membrane-based carbon capture process. We also show that the synthesis of higher-electron products such as CH4, CH3OH, C2H4, and C2H5OH can be more favorable for the robust operation of integrated AP system. A design of the fully integrated AP system is proposed that uses moisture-gradient across the anion-exchange membrane to capture CO2 from the air, which is then converted directly to fuels using water, and sunlight. Such a fully integrated AP system can produce ~0.4 ton/day of CO at a cost of ~$185/ton and STF efficiency of ~14% while reducing the CO2 level of the surrounding air by 10% at steady-state operation. The fully integrated AP systems are modular, scalable, and ~14 times more efficient than natural leaves.

ACS Style

Aditya Prajapati; Meenesh R. Singh. Assessment of Artificial Photosynthetic Systems for Integrated Carbon Capture and Conversion. ACS Sustainable Chemistry & Engineering 2019, 7, 5993 -6003.

AMA Style

Aditya Prajapati, Meenesh R. Singh. Assessment of Artificial Photosynthetic Systems for Integrated Carbon Capture and Conversion. ACS Sustainable Chemistry & Engineering. 2019; 7 (6):5993-6003.

Chicago/Turabian Style

Aditya Prajapati; Meenesh R. Singh. 2019. "Assessment of Artificial Photosynthetic Systems for Integrated Carbon Capture and Conversion." ACS Sustainable Chemistry & Engineering 7, no. 6: 5993-6003.

Book chapter
Published: 10 September 2018 in Electrochemical Methods for Hydrogen Production
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In this chapter, we discuss the methodology beyond the mathematical modeling of solar water-splitting cells. In particular, we focus on the governing mathematical equations and relationships at the continuum level for mass, energy, light, and species transport and interactions as well as their implementation in a multiscale, multiphysics model. The chapter also discusses the rationale and objectives of continuum modeling including relevant perspective and cell-design case studies that encompass limiting cases. Throughout, possible issues with modeling and their mitigation are introduced so as to help the reader understand the pitfalls and power of modeling.

ACS Style

Meenesh R. Singh; Sophia Haussener; Adam Z. Weber. Chapter 13. Continuum-scale Modeling of Solar Water-splitting Devices. Electrochemical Methods for Hydrogen Production 2018, 500 -536.

AMA Style

Meenesh R. Singh, Sophia Haussener, Adam Z. Weber. Chapter 13. Continuum-scale Modeling of Solar Water-splitting Devices. Electrochemical Methods for Hydrogen Production. 2018; ():500-536.

Chicago/Turabian Style

Meenesh R. Singh; Sophia Haussener; Adam Z. Weber. 2018. "Chapter 13. Continuum-scale Modeling of Solar Water-splitting Devices." Electrochemical Methods for Hydrogen Production , no. : 500-536.

Journal article
Published: 05 February 2018 in IEEE Transactions on Biomedical Engineering
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Objective: Proximal obstruction due to cellular material is a major cause of shunt failure in hydrocephalus management. The standard approach to treat such cases involves surgical intervention which unfortunately is accompanied by inherent surgical risks and a likelihood of future malfunction. We report a prototype design of a proximal ventricular catheter capable of non-invasively clearing cellular obstruction. Methods: In vitro cell-culture methods show that low-intensity AC signals successfully destroyed a cellular layer in a localized manner by means of Joule heating induced hyperthermia. A detailed electrochemical model for determining the temperature distribution and ionic current density for an implanted ventricular catheter support our experimental observations. Results: In-vitro experiments with cells cultured in a plate as well as cells seeded in mock ventricular catheters demonstrated that localized heating between 43°C to 48°C caused cell death. This temperatures range is consistent with hyperthermia. The electrochemical model verified that Joule heating due to ionic motion is the primary contributor to heat generation. Conclusion: Hyperthermia induced by Joule heating can clear cellular material in a localized manner. This approach is feasible to design a non-invasive self-clearing ventricular catheter system. Significance: A shunt system capable of clearing cellular obstruction could significantly reduce the need for future surgical interventions, lower the cost of disease management and improve the quality of life for patients suffering from hydrocephalus.

ACS Style

Abhay Sane; Kevin Tangen; David Frim; Meenesh R. Singh; Andreas A. Linninger. Cellular Obstruction Clearance in Proximal Ventricular Catheters Using Low-Voltage Joule Heating. IEEE Transactions on Biomedical Engineering 2018, 65, 2503 -2511.

AMA Style

Abhay Sane, Kevin Tangen, David Frim, Meenesh R. Singh, Andreas A. Linninger. Cellular Obstruction Clearance in Proximal Ventricular Catheters Using Low-Voltage Joule Heating. IEEE Transactions on Biomedical Engineering. 2018; 65 (11):2503-2511.

Chicago/Turabian Style

Abhay Sane; Kevin Tangen; David Frim; Meenesh R. Singh; Andreas A. Linninger. 2018. "Cellular Obstruction Clearance in Proximal Ventricular Catheters Using Low-Voltage Joule Heating." IEEE Transactions on Biomedical Engineering 65, no. 11: 2503-2511.

Journal article
Published: 02 October 2017 in Proceedings of the National Academy of Sciences
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Electrochemical reduction of CO2 using renewable sources of electrical energy holds promise for converting CO2 to fuels and chemicals. Since this process is complex and involves a large number of species and physical phenomena, a comprehensive understanding of the factors controlling product distribution is required. While the most plausible reaction pathway is usually identified from quantum-chemical calculation of the lowest free-energy pathway, this approach can be misleading when coverages of adsorbed species determined for alternative mechanism differ significantly, since elementary reaction rates depend on the product of the rate coefficient and the coverage of species involved in the reaction. Moreover, cathode polarization can influence the kinetics of CO2 reduction. Here, we present a multiscale framework for ab initio simulation of the electrochemical reduction of CO2 over an Ag(110) surface. A continuum model for species transport is combined with a microkinetic model for the cathode reaction dynamics. Free energies of activation for all elementary reactions are determined from density functional theory calculations. Using this approach, three alternative mechanisms for CO2 reduction were examined. The rate-limiting step in each mechanism is **COOH formation at higher negative potentials. However, only via the multiscale simulation was it possible to identify the mechanism that leads to a dependence of the rate of CO formation on the partial pressure of CO2 that is consistent with experiments. Simulations based on this mechanism also describe the dependence of the H2 and CO current densities on cathode voltage that are in strikingly good agreement with experimental observation.

ACS Style

Meenesh R. Singh; Jason D. Goodpaster; Adam Z. Weber; Martin Head-Gordon; Alexis T. Bell. Mechanistic insights into electrochemical reduction of CO2 over Ag using density functional theory and transport models. Proceedings of the National Academy of Sciences 2017, 114, E8812 -E8821.

AMA Style

Meenesh R. Singh, Jason D. Goodpaster, Adam Z. Weber, Martin Head-Gordon, Alexis T. Bell. Mechanistic insights into electrochemical reduction of CO2 over Ag using density functional theory and transport models. Proceedings of the National Academy of Sciences. 2017; 114 (42):E8812-E8821.

Chicago/Turabian Style

Meenesh R. Singh; Jason D. Goodpaster; Adam Z. Weber; Martin Head-Gordon; Alexis T. Bell. 2017. "Mechanistic insights into electrochemical reduction of CO2 over Ag using density functional theory and transport models." Proceedings of the National Academy of Sciences 114, no. 42: E8812-E8821.

Journals
Published: 23 February 2017 in Sustainable Energy & Fuels
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Operating conditions and design principles for the efficient operation of solar-fuel generators with active flow of near-neutral pH electrolytes.

ACS Style

Meenesh R. Singh; Chengxiang Xiang; Nathan S. Lewis. Evaluation of flow schemes for near-neutral pH electrolytes in solar-fuel generators. Sustainable Energy & Fuels 2017, 1, 458 -466.

AMA Style

Meenesh R. Singh, Chengxiang Xiang, Nathan S. Lewis. Evaluation of flow schemes for near-neutral pH electrolytes in solar-fuel generators. Sustainable Energy & Fuels. 2017; 1 (3):458-466.

Chicago/Turabian Style

Meenesh R. Singh; Chengxiang Xiang; Nathan S. Lewis. 2017. "Evaluation of flow schemes for near-neutral pH electrolytes in solar-fuel generators." Sustainable Energy & Fuels 1, no. 3: 458-466.

Journal article
Published: 06 October 2016 in Angewandte Chemie
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Eine integrierte Zelle für die solargetriebene Wasserspaltung besteht aus mehreren funktionellen Komponenten und kombiniert verschiedene photoelektrochemische (PEC-)Prozesse auf unterschiedlichen Längen- und Zeitskalen. Der Gesamtwirkungsgrad eines derartigen Systems für die Umwandlung von Solarenergie in Wasserstoff (solar-to-hydrogen; STH) wird von der Leistung und den Materialeigenschaften seiner Einzelkomponenten sowie ihrer Integration, von seiner Gesamtarchitektur und den Betriebsbedingungen bestimmt. Dieser Aufsatz beschäftigt sich mit der Implementierung von solargetriebenen Prototypen für die Wasserspaltung auf der Basis von Modellierungen und Simulationen, welche die Wechselwirkungen zwischen den Einzelbauteilen in ihrer Gesamtheit berücksichtigen. Physik und Wechselwirkungen innerhalb der Zelle werden diskutiert, und die Anwendung des Zellmodells für die Bestimmung der benötigten Materialeigenschaften sowie beim Design von herkömmlichen und ungewöhnlichen Architekturen wird erörtert.

ACS Style

Chengxiang Xiang; Adam Z. Weber; Shane Ardo; Alan Berger; Yikai Chen; Robert Coridan; Katherine T. Fountaine; Sophia Haussener; Shu Hu; Rui Liu; Nathan S. Lewis; Miguel A. Modestino; Matthew M. Shaner; Meenesh Singh; John C. Stevens; Ke Sun; Karl Walczak. Modellierung, Simulation und Implementierung von Zellen für die solargetriebene Wasserspaltung. Angewandte Chemie 2016, 128, 13168 -13183.

AMA Style

Chengxiang Xiang, Adam Z. Weber, Shane Ardo, Alan Berger, Yikai Chen, Robert Coridan, Katherine T. Fountaine, Sophia Haussener, Shu Hu, Rui Liu, Nathan S. Lewis, Miguel A. Modestino, Matthew M. Shaner, Meenesh Singh, John C. Stevens, Ke Sun, Karl Walczak. Modellierung, Simulation und Implementierung von Zellen für die solargetriebene Wasserspaltung. Angewandte Chemie. 2016; 128 (42):13168-13183.

Chicago/Turabian Style

Chengxiang Xiang; Adam Z. Weber; Shane Ardo; Alan Berger; Yikai Chen; Robert Coridan; Katherine T. Fountaine; Sophia Haussener; Shu Hu; Rui Liu; Nathan S. Lewis; Miguel A. Modestino; Matthew M. Shaner; Meenesh Singh; John C. Stevens; Ke Sun; Karl Walczak. 2016. "Modellierung, Simulation und Implementierung von Zellen für die solargetriebene Wasserspaltung." Angewandte Chemie 128, no. 42: 13168-13183.

Review
Published: 06 October 2016 in Angewandte Chemie International Edition
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An integrated cell for the solar-driven splitting of water consists of multiple functional components and couples various photoelectrochemical (PEC) processes at different length and time scales. The overall solar-to-hydrogen (STH) conversion efficiency of such a system depends on the performance and materials properties of the individual components as well as on the component integration, overall device architecture, and system operating conditions. This Review focuses on the modeling- and simulation-guided development and implementation of solar-driven water-splitting prototypes from a holistic viewpoint that explores the various interplays between the components. The underlying physics and interactions at the cell level is are reviewed and discussed, followed by an overview of the use of the cell model to provide target properties of materials and guide the design of a range of traditional and unique device architectures.

ACS Style

Chengxiang Xiang; Adam Z. Weber; Shane Ardo; Alan Berger; Yikai Chen; Robert Coridan; Katherine T. Fountaine; Sophia Haussener; Shu Hu; Rui Liu; Nathan S. Lewis; Miguel A. Modestino; Matthew M. Shaner; Meenesh Singh; John C. Stevens; Ke Sun; Karl Walczak. Modeling, Simulation, and Implementation of Solar‐Driven Water‐Splitting Devices. Angewandte Chemie International Edition 2016, 55, 12974 -12988.

AMA Style

Chengxiang Xiang, Adam Z. Weber, Shane Ardo, Alan Berger, Yikai Chen, Robert Coridan, Katherine T. Fountaine, Sophia Haussener, Shu Hu, Rui Liu, Nathan S. Lewis, Miguel A. Modestino, Matthew M. Shaner, Meenesh Singh, John C. Stevens, Ke Sun, Karl Walczak. Modeling, Simulation, and Implementation of Solar‐Driven Water‐Splitting Devices. Angewandte Chemie International Edition. 2016; 55 (42):12974-12988.

Chicago/Turabian Style

Chengxiang Xiang; Adam Z. Weber; Shane Ardo; Alan Berger; Yikai Chen; Robert Coridan; Katherine T. Fountaine; Sophia Haussener; Shu Hu; Rui Liu; Nathan S. Lewis; Miguel A. Modestino; Matthew M. Shaner; Meenesh Singh; John C. Stevens; Ke Sun; Karl Walczak. 2016. "Modeling, Simulation, and Implementation of Solar‐Driven Water‐Splitting Devices." Angewandte Chemie International Edition 55, no. 42: 12974-12988.

Research article
Published: 26 September 2016 in Journal of the American Chemical Society
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Electrolyte cation size is known to influence the electrochemical reduction of CO2 over metals; however, a satisfactory explanation for this phenomenon has not been developed. We report here that these effects can be attributed to a previously unrecognized consequence of cation hydrolysis occurring in the vicinity of the cathode. With increasing cation size, the pKa for cation hydrolysis decreases and is sufficiently low for hydrated K+, Rb+, and Cs+ to serve as buffering agents. Buffering lowers the pH near the cathode, leading to an increase in the local concentration of dissolved CO2. The consequences of these changes are an increase in cathode activity, a decrease in Faradaic efficiencies for H2 and CH4, and an increase in Faradaic efficiencies for CO, C2H4, and C2H5OH, in full agreement with experimental observations for CO2 reduction over Ag and Cu.

ACS Style

Meenesh R. Singh; Youngkook Kwon; Yanwei Lum; Iii Joel W. Ager; Alexis T. Bell. Hydrolysis of Electrolyte Cations Enhances the Electrochemical Reduction of CO2 over Ag and Cu. Journal of the American Chemical Society 2016, 138, 13006 -13012.

AMA Style

Meenesh R. Singh, Youngkook Kwon, Yanwei Lum, Iii Joel W. Ager, Alexis T. Bell. Hydrolysis of Electrolyte Cations Enhances the Electrochemical Reduction of CO2 over Ag and Cu. Journal of the American Chemical Society. 2016; 138 (39):13006-13012.

Chicago/Turabian Style

Meenesh R. Singh; Youngkook Kwon; Yanwei Lum; Iii Joel W. Ager; Alexis T. Bell. 2016. "Hydrolysis of Electrolyte Cations Enhances the Electrochemical Reduction of CO2 over Ag and Cu." Journal of the American Chemical Society 138, no. 39: 13006-13012.

Journals
Published: 06 September 2016 in Physical Chemistry Chemical Physics
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The effect of bulk electrolyte CO2depletion and temperature on catalyst evaluation were explored when using high electrode surface area to electrolyte volume electrochemical cells for CO2reduction.

ACS Style

Peter Lobaccaro; Meenesh R. Singh; Ezra Clark; Youngkook Kwon; Alexis Bell; Joel W. Ager. Effects of temperature and gas–liquid mass transfer on the operation of small electrochemical cells for the quantitative evaluation of CO2reduction electrocatalysts. Physical Chemistry Chemical Physics 2016, 18, 26777 -26785.

AMA Style

Peter Lobaccaro, Meenesh R. Singh, Ezra Clark, Youngkook Kwon, Alexis Bell, Joel W. Ager. Effects of temperature and gas–liquid mass transfer on the operation of small electrochemical cells for the quantitative evaluation of CO2reduction electrocatalysts. Physical Chemistry Chemical Physics. 2016; 18 (38):26777-26785.

Chicago/Turabian Style

Peter Lobaccaro; Meenesh R. Singh; Ezra Clark; Youngkook Kwon; Alexis Bell; Joel W. Ager. 2016. "Effects of temperature and gas–liquid mass transfer on the operation of small electrochemical cells for the quantitative evaluation of CO2reduction electrocatalysts." Physical Chemistry Chemical Physics 18, no. 38: 26777-26785.

Research article
Published: 05 January 2016 in The Journal of Physical Chemistry C
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Chemical analysis of solid–liquid interfaces under electrochemical conditions has recently become feasible due to the development of new synchrotron radiation techniques. Here we report the use of “tender” X-ray ambient-pressure X-ray photoelectron spectroscopy (APXPS) to characterize a thin film of Ni–Fe oxyhydroxide electrodeposited on Au as the working electrode at different applied potentials in 0.1 M KOH as the electrolyte. Our results show that the as-prepared 7 nm thick Ni–Fe (50% Fe) film contains Fe and Ni in both their metallic as well as oxidized states, and undergoes further oxidation when the sample is subjected to electrochemical oxidation–reduction cycles. Metallic Fe is oxidized to Fe3+ and metallic Ni to Ni2+/3+. This work shows that it is possible to monitor the chemical nature of the Ni–Fe catalyst as a function of potential when the corresponding current densities are small. This allows for operando measurements just above the onset of OER; however, current densities as they are desired in photoelectrochemical devices (∼1–10 mA cm–2) could not be achieved in this work, due to ohmic losses in the thin electrolyte film. We use a two-dimensional model to describe the spatial distribution of the electrochemical potential, current density, and pH as a function of the position above the electrolyte meniscus, to provide guidance toward enabling the acquisition of operando APXPS at high current density. The shifts in binding energy of water with applied potential predicted by the model are in good agreement with the experimental values.

ACS Style

Harri Ali-Löytty; Mary W. Louie; Meenesh Singh; Lin Li; Hernan G. Sanchez Casalongue; Hirohito Ogasawara; Ethan J. Crumlin; Zhi Liu; Alexis Bell; Anders Nilsson; Daniel Friebel. Ambient-Pressure XPS Study of a Ni–Fe Electrocatalyst for the Oxygen Evolution Reaction. The Journal of Physical Chemistry C 2016, 120, 2247 -2253.

AMA Style

Harri Ali-Löytty, Mary W. Louie, Meenesh Singh, Lin Li, Hernan G. Sanchez Casalongue, Hirohito Ogasawara, Ethan J. Crumlin, Zhi Liu, Alexis Bell, Anders Nilsson, Daniel Friebel. Ambient-Pressure XPS Study of a Ni–Fe Electrocatalyst for the Oxygen Evolution Reaction. The Journal of Physical Chemistry C. 2016; 120 (4):2247-2253.

Chicago/Turabian Style

Harri Ali-Löytty; Mary W. Louie; Meenesh Singh; Lin Li; Hernan G. Sanchez Casalongue; Hirohito Ogasawara; Ethan J. Crumlin; Zhi Liu; Alexis Bell; Anders Nilsson; Daniel Friebel. 2016. "Ambient-Pressure XPS Study of a Ni–Fe Electrocatalyst for the Oxygen Evolution Reaction." The Journal of Physical Chemistry C 120, no. 4: 2247-2253.

Journal article
Published: 01 January 2016 in Energy & Environmental Science
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Artificial photosynthesis of liquid fuels is a potential source for clean energy. Alcohols are particularly attractive products because of their high energy density and market value per amount of energy input. The major challenges in photo/electrochemical synthesis of alcohols from sunlight, water and CO2 are low product selectivity, high membrane fuel-crossover losses, and high cost of product separation from the electrolyte. Here we propose an artificial photosynthesis scheme for direct synthesis and separation to almost pure ethanol with minimum product crossover using saturated salt electrolytes. The ethanol produced in the saturated salt electrolytes can be readily phase separated into a microemulsion, which can be collected as pure products in a liquid–liquid extractor. A novel design of an integrated artificial photosynthetic system is proposed that continuously produces >90 wt% pure ethanol using a polycrystalline copper cathode at a current density of 0.85 mA cm−2. The annual production rate of >90 wt% ethanol using such a photosynthesis system operating at 10 mA cm−2 (12% solar-to-fuel (STF) efficiency) can be 15.27 million gallons per year per square kilometer, which corresponds to 7% of the industrial ethanol production capacity of California.

ACS Style

Meenesh R. Singh; Alexis T. Bell. Design of an artificial photosynthetic system for production of alcohols in high concentration from CO 2. Energy & Environmental Science 2016, 9, 193 -199.

AMA Style

Meenesh R. Singh, Alexis T. Bell. Design of an artificial photosynthetic system for production of alcohols in high concentration from CO 2. Energy & Environmental Science. 2016; 9 (1):193-199.

Chicago/Turabian Style

Meenesh R. Singh; Alexis T. Bell. 2016. "Design of an artificial photosynthetic system for production of alcohols in high concentration from CO 2." Energy & Environmental Science 9, no. 1: 193-199.