Galvanic exchange at layered doubled hydroxide/N-doped graphene as an in-situ method to fabricate powerful electrocatalysts for hydrogen evolution reaction

Abstract

Introducing a novel strategy for growing dispersed metal nanoparticles at reduced graphene oxide (rGO) and nitrogen-doped GO (rNGO), this work aimed to design Pt-free electrocatalysts for water splitting. For this purpose, gold nanoparticles were fabricated by the in-situ galvanic exchange of layered double hydroxide (LDH) metals on rGO and rNGO. The significant roles of the galvanic exchange method, LaNi-LDH, and the Au nanoparticles synthesized on the rGO/rNGO-LaNi-LDH surface (Au@rGO/rNGO-LaNi-LDH) were investigated via a variety of methods and certain novel properties such as nitrogen-metal bridge bonds between the metal component of Au@LDH and the nitrogen component of rNGO were established, which indicated the semi-nanorod morphology of the Au@rGO/rNGO-LaNi-LDH thus produced. Electrochemical studies were used to reveal an onset potential of only −80 mV vs. RHE at an exchange current density of about 10 mA cm−2 with a small Tafel slope of 60 mV dec−1 for the hydrogen generation reaction in a 0.5 mol L−1 H2SO4 solution. The isolated island architecture of rNGO/LaNi-LDH and rNGO/Au@LaNi-LDH were found to promise rich and active sites to be exposed, which allow for the effective interaction of the reactants (e.g., protons) with these active sites.