CeO2-x Modified NiMo alloy for Alkaline Hydrogen Evolution Reaction with High Activity and Stability

Citric acid adsorbed CeO 2 forms a uniformly dispersed nanoparticle sol, acting as a special “glue” to uniformly adhere to the surface of the NiMoO 4 precursor. • Under high-temperature reduction, a CeO 2-x modified NiMo alloy with strong interaction is synthesized. • The optimized composite electrocatalyst achieves an overpotential of only 48 mV at 10 mA cm -2 with the stability for over 1,500 h at 500 mA cm -2 . • In situ Raman spectra and DFT calculations indicate that the CeO 2-x /NiMo alloy interface accelerates water dissociation and enhances alkaline HER performance. NiMo alloys are promising non-precious metal electrocatalysts for alkaline hydrogen evolution reaction (HER), however, they suffer from issues such as poor stability due to Mo leaching and insufficient intrinsic activity. In this study, a citric acid (CA) assisted CeO 2-x modification strategy is developed to prepare a CeO 2-x /NiMo alloy composite electrocatalyst with high activity and stability. CA is uniformly adsorbed onto the surface of CeO 2 nanoparticles, and the cross-linked CA network with the CeO 2 particles forms a uniformly dispersed nanoparticle sol, which acts as a special “glue” to uniformly adhere to the surface of the NiMoO 4 precursor, forming a CeO 2 /NiMoO 4 composite precursor. Following high-temperature reduction, a CeO 2-x modified NiMo alloy electrocatalyst is synthesized. Owing to the strong interaction between CeO 2-x and NiMo, the optimized composite electrocatalyst achieves a current density of 10 mA cm -2 at an overpotential of only 48 mV and it maintains high stability for over 1500 h at a current density of 500 mA cm -2 , which is three times longer than that of the unmodified NiMo alloy electrocatalyst, outperforming most reported nickel-molybdenum-based electrocatalysts. In situ Raman spectra and density functional theory calculations indicate that the CeO 2-x /NiMo alloy interface accelerates water dissociation, hydrogen combination and enhances alkaline HER performance. This work provides a new approach for the preparation of highly active and stable nickel-molybdenum-based hydrogen evolution catalysts. A citric acid assisted CeO 2-x modification strategy is developed to prepare a highly-active and stabile CeO 2-x /NiMo alloy electrocatalyst for HER. Download: Download high-res image (267KB) Download: Download full-size image