A simple approach for the deposition of Au and Ag nanoparticles on ZnO surface and to investigate their application in pollutant degradation.

Different metal chalcogenides, being a potential candidate for hydrogen evolution catalysts, have attracted enormous attention in the field of water splitting. In the present study, AgS/Ag is revealed as an efficient catalyst for hydrogen evolution. When a sacrificial template of the CuS nanostructure is used, AgS/Ag heterostructures are synthesized following a simple wet-chemical technique. Two different routes, wet chemical and hydrothermal, are followed to modulate the morphology of the CuS templates from flower ball to wirelike structures, which subsequently results in the formation of AgS nanostructure. Finally, the Ag layer is deposited on AgS with the help of a photoreduction technique. The unique heterostructure of AgS/Ag shows efficient catalytic activity in the H evolution reaction. A AgS/Ag wire can successfully generate a 10 mA/cm current density at a -0.199 V potential. AgS/Ag contains the micronanostructure where nanoplates of AgS/Ag assemble to give rise to microstructures such as flower balls and wire.

An efficient Hydrogen evolution catalyst has been developed by decorating Au nanoparticle on the surface of CuS nanostructure following a green and environmental friendly approach. CuS nanostructure is synthesized through a simple wet-chemical route. CuS being a visible light photocatalyst is introduced to function as an efficient reducing agent. Photogenerated electron is used to reduce Au(III) on the surface of CuS to prepare CuS/Au heterostructure. The as-obtained heterostructure shows excellent performance in electrochemical H2 evolution reaction with promising durability in acidic condition, which could work as an efficient alternative for novel metals. The most efficient CuS-Au heterostructure can generate 10 mA/cm2 current density upon application of 0.179 V vs. RHE. CuS-Au heterostructure can also perform as an efficient photocatalyst for the degradation of organic pollutant. This dual nature of CuS and CuS/Au both in electrocatalysis and photocatalysis has been unveiled in this study.

In this study, we report the synthesis of monometallic (Au and Pd) and bimetallic (AuPd) nanoparticles (NPs) using graphitic carbon nitride (g-CN) quantum dots (QDs) and photochemical routes. Eliminating the necessity of any extra stabilizer or reducing agent, the photochemical reactions have been carried out using a UV light source of 365 nm where CN QD itself functions as a suitable stabilizer as well as a reducing agent. The g-CN QDs are excited upon irradiation with UV light and produce photogenerated electrons, which further facilitate the reduction of metal ions. The successful formation of Au, Pd, and AuPd alloy nanoparticles is evidenced by UV-vis, powder X-ray diffraction, X-ray photon spectroscopy, and energy-dispersive spectroscopy techniques. The morphology and distribution of metal nanoparticles over the CN QD surface has been systematically investigated by high-resolution transmission electron microscopy (HRTEM) and SAED analysis. To explore the catalytic activity of the as-prepared samples, the reduction reaction of 4-nitrophenol with excellent performance is also investigated. It is noteworthy that the synthesis of both monometallic and bimetallic NPs can be accomplished by using a very small amount of g-CN, which can be used as a promising photoreducing material as well as a stabilizer for the synthesis of various metal nanoparticles.

Here, we propose the synthesis of AgPt, AgPd, and AgAu bimetallic nanoparticles (NPs) on a carbon nitride (C 3 N 4 ) surface via a galvanic exchange technique for the hydrogen evolution reaction (HER). Prior to the synthesis of C 3 N 4 / AgPt, AgPd, and AgAu, Ag NPs were synthesized on a C 3 N 4 surface. For the synthesis of Ag NPs, initially Ag + ions were adsorbed and then reduced by NaBH 4 resulting in the decoration of Ag NPs. These Ag NPs were then subjected to galvanic exchange where sacrificial Ag was replaced by Pt 2+ , Pd 2+ , and Au 3+ to fabricate AgPt, AgPd, and AgAu NPs. The galvanic exchange reaction occurs on a solid substrate, which favored slow exchange of Ag and resulted in the transformation of Ag into AgPt, AgPd, and AgAu alloys. The synthesized heterostructures were characterized with the help of PXRD, XPS, TEM, FESEM, and EDS techniques. All the materials were applied for hydrogen evolution using 0.5 M H 2 SO 4 solution. C 3 N 4 /AgPt shows efficient electrocatalytic activity as it requires only −150 mV potential to attain current density of 10 mA/cm 2 . Bimetallic catalysts synthesized through galvanic exchange proved very efficient as compared to monometallic C 3 N 4 /Ag.