Synthesis, Characterization and Application of SnO₂@rGO Nanocomposite for Selective Catalytic Reduction of Exhaust Emission in Internal Combustion Engines

In this experimental investigation, a procreation approach was used to produce a catalyst based on SnO2@rGO nanocomposite for use in a selective catalytic reduction (SCR) system. Plastic waste oil is one such alternative that helps to ensure the survival of fossil fuels and also lessens the negative impacts of improper waste disposal. The SnO2@rGO nanocomposite was prepared by fine dispersion of SnO2 nanoparticles on monolayer-dispersed reduced graphene oxide (rGO) and carefully investigated for its potential in adsorbing CO, CO2, NOX, and hydrocarbon (HC). The as-synthesized SnO2@rGO nanocomposite was characterized by Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, scanning electron microscopy, X-ray diffraction spectroscopy, thermogravimetry, and surface area analyses. Then, the impact of catalysts inside the exhaust engine system was evaluated in a realistic setting with a single-cylinder, direct-injection diesel engine. As a result, the catalysts reduced harmful pollution emissions while marginally increasing brake-specific fuel consumption. The nanocomposite was shown to exhibit higher NOX adsorption efficiencies when working with different toxic gases. Maximum reductions in the emission of NOX, hydrocarbons, and CO were achieved at a rate of 78%, 62%, and 15%, respectively. These harmful pollutants were adsorbed on the active sites of catalyst and are converted to useful fuel gases through catalytic reduction thereby hindering the trajectory of global warming

Detoxification of Toxic Organic Dye by Heteroatom-Doped Fluorescent Carbon Dots Prepared by Green Hydrothermal Method Using <i>Garcinia mangostana</i> Extract

In this work, nitrogen- and oxygen-doped fluorescent carbon dots (NOFCDs) were prepared using a simple green hydrothermal carbonization technique. Aqueous ammonia and the plant extract of Garcinia mangostana were used as a source of nitrogen and carbon, respectively. The prepared NOFCDs were examined using a variety of microscopic and spectroscopic techniques for physicochemical characterization. Fluorescence and UV–visible spectroscopy measurements were used to analyze the NOFCDs’ excitation-dependent fluorescent emission and absorption nature. It is observed that fluorescence intensity was excited at 320 nm and the strongest emission peak absorbed at 405 nm. The HRTEM imaging revealed NOFCDs to be spherical in shape with particle size at 3.58 nm. Moreover, the amorphous nature of NOFCDs was verified by X-ray diffraction, Raman spectroscopy, and SAED pattern techniques. Through FTIR, XPS, and EDS investigations, the doping of nitrogen and oxygen over the surface of the NOFCDs was evaluated and validated. The presence of carboxylic, amine, hydroxyl, and carbonyl functional groups on NOFCDs’ surface was shown by XPS and FTIR investigations. By using NaBH4, the obtained NOFCDs were demonstrated to possess excellent catalytic activity in the detoxification of methylene blue. Overall, this study revealed that the NOFCDs synthesized from green sources could be a promising material for catalytic and environmental remediation applications