Fast operando spectroscopy tracking in situ generation of rich defects in silver nanocrystals for highly selective electrochemical CO2 reduction

Electrochemical CO2 reduction (ECR) is highly attractive to curb global warming. The knowledge on the evolution of catalysts and identification of active sites during the reaction is important, but still limited. Here, we report an efficient catalyst (Ag-D) with suitable defect concentration operando formed during ECR within several minutes. Utilizing the powerful fast operando X-ray absorption spectroscopy, the evolving electronic and crystal structures are unraveled under ECR condition. The catalyst exhibits a ~100% faradaic efficiency and negligible performance degradation over a 120-hour test at a moderate overpotential of 0.7 V in an H-cell reactor and a current density of ~180 mA cm−2 at −1.0 V vs. reversible hydrogen electrode in a flow-cell reactor. Density functional theory calculations indicate that the adsorption of intermediate COOH could be enhanced and the free energy of the reaction pathways could be optimized by an appropriate defect concentration, rationalizing the experimental observation.

Mathematical Modeling of Bio Hydrogen Production in Microbial Electrolysis Cell Reactor

Mathematical modeling of biohydrogen production in microbial electrolysis cell reactor is discussed. This study explains the mathematical model for the production of hydrogen from a wastewater batch reactor, and it contains a system of non-linear equations. The non-linear differential equation of this model is solved by the Homotopy perturbation method. The approximate analytical expression of this model, concentration of substrate, anodophilic microorganisms, acetoclastic microorganism, hydrogenotrophic microorganisms, and Oxidized mediator are obtained. The effect of various values of the parameters on the reactions is discussed. The analytical solutions are also compared with simulation results and satisfactory the agreement is noted.

Electrochemical Degradation of Reactive Red 195 from its Aqueous Solution using RuO2/IrO2/TaO2 Coated Titanium Electrodes

The electrochemical oxidation of reactive red 195 from aqueous solution was carried out using titanium electrode in an electrochemical cell reactor. The effect of different operating parameters such as dye concentration, current density, electrolyte concentration, pH and stirring speed were investigated. The UV-visible spectroscopy confirmed the removal and degradation of reactive red 195. Three different supporting electrolytes such as NaCl, NaNO3 and Na2SO4 were used for electrolysis and NaCl were found to be effective for the removal of reactive red 195 dye from its aqueous solution. The maximum percentage of colour removal was 94%, under the optimum operating conditions with electrolyte (NaCl) concentration 0.075 M, current density 25 mA/cm2, pH 5 and stirring speed of 250 rpm. This method was found to be relatively more effective to the conventional treatment techniques.