Silver nanoparticle-decorated NiFe2O4/CuWO4 heterostructure electrocatalyst for oxygen evolution reactions.

In this work, Ag nanoparticles decorated with NiFe2O4/CuWO4 heterostructure were synthesized using the step-wise precipitation method. The influence of varying Ag loading on the NiFe2O4/CuWO4 heterostructure and its electrochemical OER performance was extensively studied in 1 M KOH electrolyte. The obtained LSV profile was analyzed to determine the overpotential, Tafel slope, and onset potential. The heterostructure with an optimal Ag loading of 5 wt% required the least overpotential (1.60 V vs. RHE) for generating a current density of 10 mA cm-2 with a lower Tafel slope of 44.5 mV dec-1, indicating its faster OER kinetics. Furthermore, the composite remained stable over a period of 24 hours with a minimum rise in the overpotential after the stability test. The enhanced OER performance of the as-prepared catalyst can be attributed to the presence of multiple metallic elements in the Ag-loaded NiFe2O4/CuWO4 composite, which created a diverse array of oxygen-vacant sites with varying reactivity, enhancing the charge-transfer kinetics; and thus contributing to the overall efficiency of OER. Therefore, optimizing the Ag concentration and engineering a microstructure represents an encouraging strategy for developing cost-effective catalysts for next-generation energy-conversion applications.

AgI/CuWO4 Z-scheme photocatalyst for the degradation of organic pollutants: Experimental and molecular dynamics studies.

While the knowledge of the adsorption properties of components of a composite heterogeneous photocatalyst is critical to its applicability to a particular reaction, there has been little research in this direction. The present research is on the development of AgI/CuWO4 nanocomposites that photocatalytically degraded ciprofloxacin and rhodamine B in an aqueous medium under visible light irradiation. The nanocomposites were prepared by a step-wise precipitation protocol. XPS analysis and active species trapping experiments demonstrated that the photocatalysis proceeded by a Z-scheme mechanism. Large scale aqueous medium molecular dynamics simulations showed that oxygen and CIP adsorb on the AgI part, while water interacts intensely with the CuWO4 component. Information from experimental and molecular dynamics studies was combined to arrive at the photocatalysis mechanism.