Decoration of Carbon Nitride Surface with Bimetallic Nanoparticles (Ag/Pt, Ag/Pd, and Ag/Au) via Galvanic Exchange for Hydrogen Evolution Reaction

Abstract

Here, we propose the synthesis of AgPt, AgPd, and AgAu bimetallic nanoparticles (NPs) on a carbon nitride (C3N4) surface via a galvanic exchange technique for the hydrogen evolution reaction (HER). Prior to the synthesis of C3N4/AgPt, AgPd, and AgAu, Ag NPs were synthesized on a C3N4 surface. For the synthesis of Ag NPs, initially Ag+ ions were adsorbed and then reduced by NaBH4 resulting in the decoration of Ag NPs. These Ag NPs were then subjected to galvanic exchange where sacrificial Ag was replaced by Pt2+, Pd2+, and Au3+ 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 H2SO4 solution. C3N4/AgPt shows efficient electrocatalytic activity as it requires only −150 mV potential to attain current density of 10 mA/cm2. Bimetallic catalysts synthesized through galvanic exchange proved very efficient as compared to monometallic C3N4/Ag.