This paper evaluates the potential of hydrogen (H₂) and ammonia (NH₃) as carbon-free fuels. The combustion characteristics and NO_x formation in the combustion of H₂ and NH₃ at different air-fuel equivalence ratios and initial H₂ concentrations in the fuel gas were experimentally studied. NH₃ burning velocity improved because of increased amounts of H₂ atom in flame with the addition of H₂. NH₃ burning velocity could be moderately improved and could be applied to the commercial gas engine together with H₂ as fuels. H₂ has an accelerant role in H₂–NH₃–air combustion, whereas NH₃ has a major effect on the maximum burning velocity of H₂–NH₃–air. In addition, fuel-NO_x has a dominant role and thermal-NO_x has a negligible role in H₂–NH₃–air combustion. Thermal-NO_x decreases in H₂–NH₃–air combustion compared with pure H₂–air combustion. NO_x concentration reaches its maximum at stoichiometric combustion. Furthermore, H₂ is detected at an air-fuel equivalence ratio of 1.00 for the decomposition of NH₃ in flame. Hence, the stoichiometric combustion of H₂ and NH₃ should be carefully considered in the practical utilization of H₂ and NH₃ as fuels. H₂ as fuel for improving burning performance with moderate burning velocity and NO_x emission enables the utilization of H₂ and NH₃ as promising fuels. Copyright © 2014 John Wiley & Sons, Ltd.

Combustion and heat release characteristics of biogas non-premixed flames under various hydrogen-enriched and oxygen-enriched conditions were investigated through chemical kinetics simulation using detailed chemical mechanisms. The heat release rates, chemical reaction rates, and molar fraction of all species of biogas at various methane contents (35.3–58.7%, mass fraction), hydrogen addition ratios (10–50%), and oxygen enrichment levels (21–35%) were calculated considering the GRI 3.0 mechanism and P1 radiation model. Results showed that the net reaction rate of biogas increases with increasing hydrogen addition ratio and oxygen levels, leading to a higher net heat release rate of biogas flame. Meanwhile, flame length was shortened with the increase in hydrogen addition ratio and oxygen levels. The formation of free radicals, such as H, O, and OH, are enhanced with increase in hydrogen addition ratio and oxygen levels. Higher reaction rates of exothermic elementary reactions, especially those with OH free radical are increased, are beneficial to the improvement in combustion and heat release characteristics of biogas in practical applications.

3D carbon modified LiOH·H₂O particles were well dispersed into nanoparticles (5–15 nm) and tested using in situ DRIFT spectroscopy.

Carbon nanospheres (CNSs) and multi-walled carbon nanotubes (MWCNTs) as nanoadditives were used to modify lithium hydroxide monohydrate for low temperature chemical heat storage application. The lithium hydroxide monohydrate particles were well dispersed on the nanoscale level, and the diameter of nanoparticles was about 20–30 nm in the case of the carbon nanospheres and 50–100 nm the case of the MWCNTs, as shown by transmission electron microscopy characterization results. X-ray diffraction results indicated that the LiOH·H₂O-carbon nano thermochemical composite materials were successfully synthesized. The thermochemical composite materials LiOH·H₂O/CNSs (2020 kJ/kg), LiOH·H₂O/MWCNTs (1804 kJ/kg), and LiOH·H₂O/AC (1236 kJ/kg) exhibited obviously improved heat storage density and higher hydration rate than pure LiOH·H₂O (661 kJ/kg), which was shown by thermogravimetric and differential scanning calorimetric (TG-DSC) analysis. It appears that nanocarbon-modified lithium hydroxide monohydrate thermochemical composite materials have a huge potential for the application of low temperature chemical heat storage.

Cocatalysts have been extensively used to accelerate the rate of hydrogen evolution in semiconductor-based photocatalytic systems; however, the influence of interface states between the semiconductor and cocatalyst has rarely been investigated. Herein, we demonstrated a feasible strategy of heterogeneous structure to enhance visible light hydrogen generation of the MoS₂/B-TiO₂ system. Loading of MoS₂ nanosheets on the surface of anatase boron doped TiO₂ (B-TiO₂) nanosheets with exposed {001} facets considerably increases the interfacial contact. At an optimal ratio of 1.0 wt% MoS₂, the MoS₂/B-TiO₂ hybrid photocatalyst showed the highest H₂ evolution rate of 0.50 mmol h⁻¹ g⁻¹, which is almost 6 times higher than that of pure B-TiO₂ nanosheets. More importantly, the MoS₂/B-TiO₂ hybrid photocatalyst exhibited photocatalytic activity much higher than that of Pt/B-TiO₂ nanosheets and the simple mechanical mixing of B-TiO₂ and MoS₂ nanosheets photocatalysts. The decisive factor in improving the photocatalytic H₂ production activity is an intimate and large contact interface between the light-harvesting semiconductor and cocatalyst. The effective charge transfers from B-TiO₂ to MoS₂ was demonstrated by the significant enhancement of the photocurrent responses in MoS₂/B-TiO₂ hybrid electrodes. This study created new opportunities for designing and constructing highly efficient visible light photocatalysts by surface modification or doping.