Cr-Doped CeO₂ Nanocrystals Supported on Reduced Graphene Oxide Nanosheets for Electrocatalytic Hydrogen Evolution

Abstract

The advancement of cost-effective and highly efficient electrocatalysts for hydrogen evolution is pivotal in fostering the progress of clean energy technologies. In this study, we present a reforming approach aimed at facile fabrication of the Cr-CeO2/rGO electrocatalyst. This involves incorporating a limited quantity of reduced graphene oxide (rGO) to serve as a conductive scaffold for CeO2 nanocrystals (NCs) while also introducing Cr, a transition metal, as an active dopant. It is found that the introduction of Cr and rGO induces charge transfer, leading to enhanced electrical conductivity and the creation of additional active sites on the nanocomposite surface. The synergy between rGO and CeO2, along with Cr doping in CeO2, significantly improves HER performance. The representative sample of the Cr(5%)-CeO2/rGO catalyst demonstrates a low overpotential of 83 mV at a current density of 10 mA cm–2, a low Tafel slope of 81 mV dec–1, and excellent stability under alkaline conditions. Significantly, this value of overpotential is reduced by 81 and 127 mV compared to those of the CeO2/rGO nanocomposites and the pristine CeO2 NCs. Theoretical density functional theory calculations additionally validate the phenomenon of charge transfer and improved HER properties, with Cr-CeO2 displaying a favorable Gibbs free energy (ΔG H*) for H* adsorption. This study offers novel insights into the design of precious metal electrocatalysts featuring functional interfaces and a wealth of active sites, holding great promise for industrial applications in clean energy conversion and storage.