Mo-doped Ni/NiO supported on oxygen-deficient NiMoO4 with carbon derived from tannic acid for hydrogen evolution and hydrogen oxidation

The widespread deployment of anion exchange membrane unitized reversible fuel cells is contingent upon the development of stable and efficient non-precious metal electrocatalysts for the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER). This study reports on the synthesis of Mo-doped Ni/NiO hetero-nanoparticles supported on oxygen-deficient NiMoO4 (NiMoOX), with tannic acid (TA) integrated as both a carbon source and stabilizing agent (Ni/NiO-Mo/C@NiMoOX). In situ Raman spectroscopy elucidates the mechanism through which TA enhances the electrocatalytic activity. The resultant catalyst demonstrates superior HOR/HER performance, featuring a current density of 2.5 mA cm−2 at 100 mV overpotential for HOR, remaining stable for 24 h, and in HER, exhibiting a remarkably low overpotential of just −12 mV at a current density of −10 mA cm−2, with stability persisting for over 300 h, outperforming the commercial Pt/C catalyst.