We report a photonic technique to instantaneously synthesize cobalt oxide reduced graphitic oxide (CoO_x-rGO) supercapacitor electrodes. The electrode processing is achieved through rapidly heating the precursor material by irradiation of high-energy pulsed mostly visible light from a xenon lamp. Due to the short duration of the light pulse, we prepared the electrodes at room temperature instantaneously (ms), thus eliminating the several hours of processing times of the conventional techniques. The as-prepared electrodes exhibited a highly porous morphology, allowing for enhanced ionic transport during electrochemical interactions. The electrochemical properties of the CoO_x-rGO electrodes were studied in 1 M KOH aqueous electrolyte. The non-rectangular cyclic voltammetry (CV) curves with characteristic redox peaks indicated the pseudocapacitive charge storage mechanism of the electrodes. From the discharge curves at 0.4 mA/cm² and 1.6 A/g constant current densities, the electrode showed areal specific capacitance of 17 mF/cm² and specific capacitance of 69 F/g, respectively. Cyclic stability was tested by performing 30,000 galvanostatic charge–discharge (GCD) cycles and the electrode exhibited 65% capacitance retention, showing its excellent electrochemical performance and ultra-long cycle life. The excellent electrochemical electrode properties are attributed to the unique processing technique, optimum processing parameters, improved conductivity due to the presence of rGO, and highly porous morphology which offers a high specific surface area. The novel photonic processing we report allows for high-temperature heating of the precursor films achieved via non-radiative recombination of photogenerated electron holes pairs during irradiation. Such extremely quick (ms) heating followed by instantaneous cooling results in the formation of a dense and robust bottom layer of the electrode, resulting in a long cycle life.

Fabrication of non-functionalized gold nanoparticles is interesting owing to their potential applications in sensing and biomedicine. We report on the synthesis of surfactant-free gold nanoparticles (AuNPs) by Plasma-Liquid Interaction (PLI) technique, using micro-atmospheric pressure D.C. plasma. The effects of discharge parameters, such as discharge current, precursor concentration and gas flow rates on the structure and morphology of AuNPs have been investigated. Optical Emission Spectroscopy (OES) was employed to estimate the UV radiation intensity and OH radical density. Scanning electron microscopy (SEM) and ultraviolet-visible (UV-Vis) optical spectroscopy were employed to study the morphology and structure of AuNPs. The normalized intensities of UV radiation and OH radical density found to increase with increase in discharge current. We observed that the particle size can be tuned by controlling any of the following parameters: intensity of the UV radiation, OH radical density, and concentration of the Au precursor. Interestingly, we found that addition of 1% Ar in the feedstock gas results in formation of relatively uniform size distribution of nanoparticles. The surfactant-free AuNPs, due to their bare-surface, exhibit excellent surface-enhanced Raman scattering (SERS) properties. The SERS study of Rhodamine 6G using AuNPs as substrates, shows significant Raman enhancement and fluorescence quenching, which makes our technique a potentially powerful route to detection of trace amounts of dangerous explosives and other materials.

Silicon and Germanium oxide (SiO_x and GeO_x) nanostructures are promising materials for energy storage applications due to their potentially high energy density, large lithiation capacity (~10X carbon), low toxicity, low cost, and high thermal stability. This work reports a unique approach to achieving controlled synthesis of SiO_x and GeO_x nanostructures via photonic curing. Unlike conventional methods like rapid thermal annealing, quenching during pulsed photonic curing occurs rapidly (sub‐millisecond), allowing the trapping of metastable states to form unique phases and nanostructures. We explored the possible underlying mechanism of photonic curing by incorporating laws of photophysics, photochemistry, and simulated temperature profile of thin film. The results show that photonic curing of spray coated 0.1 M molarity Si and Ge Acetyl Acetate precursor solution, at total fluence 80 J cm⁻² can yield GeO_x and SiO_x nanostructures. The as‐synthesized nanostructures are ester functionalized due to photoinitiated chemical reactions in thin film during photonic curing. Results also showed that nanoparticle size changes from ~48 nm to ~11 nm if overall fluence is increased by increasing the number of pulses. These results are an important contribution towards large‐scale synthesis of the Ge and Si oxide nanostructured materials which is necessary for next‐generation energy storage devices.

Intercalation is a powerful approach to customize the properties of layered materials such as titanium carbide (Ti₃C₂T_x) MXenes. Photonic curing, a novel technique employing intense pulsed light from a xenon flashlamp (≈280–1100 nm wavelength range), offers significant advantages over conventional annealing methods. The pulsed nature of photonic curing enables rapid quenching, which allows trapping of metastable states and the formation of unique nanostructures. Herein, this work reports on the ion exchange intercalation of Ti₃C₂T_x MXenes with aminopropyl terminated polydimethylsiloxane (amino‐PDMS) and the subsequent application of photonic curing to study pyrolysis of intercalated PDMS. The results showed an increase in the interlayer spacing (d‐spacing) of Ti₃C₂T_x from 1 to 13.5 nm for the 5 kg mol⁻¹ amino‐PDMS (5K‐PDMS) intercalant. After photonic curing, the intercalated PDMS is converted into SiO_x or silicon oxycarbide, and the d‐spacing decreased from 13.5 to 11 nm. Furthermore, curing the intercalated MXenes under controlled pressure in different gas environments, this work observes the conversion of PDMS to silicon carbide on the surface of MXenes layers. This study demonstrates the potential of photonic curing as a promising approach for cost‐effective, instantaneous, and scalable synthesis of customizable layered materials with precise control over the nanostructure within the layers.

Surfactant free AuNPs were prepared via Plasma-Liquid Interaction (PLI) technique, using μ-plasma, as a function of PLI time and gas flow type. Atomic oxygen [O] and nitrogen [N] densities were determined to study their effect on the intensities of UV radiation and OH radical, which controls the synthesis of AuNPs. UV radiation intensity, OH radical and atomic densities of [O] and [N] were determined through optical emission spectroscopy. The increase in UV radiation and OH radicals' intensities with time was observed and results were verified by observing increasing trend in the [O] and [N]. We report the controlled synthesis of surfactant free AuNPs, via PLIs, by controlling a novel and versatile plasma parameter, like [O] atomic and [N]atomic density.