Multi-metal doped Bi₂O₃ nanowires with enhanced oxygen evolution reaction performance

Hydrogen production from electrolyzed water, when coupled with green power generation technology, can achieve carbon-free hydrogen production. Designing and synthesizing non-noble metal-based electrocatalysts is crucial for advancing hydrogen production from electrolytic water. Non-noble metal oxide, one-dimensional Bi₂O₃ nanowires, owing to their unique nanowire morphology, offer the benefits of a large specific surface area and high conductivity. These properties make them potential candidates for oxygen evolution reaction (OER) applications. In this work, we sequentially designed and synthesized a series of multi-metal doped Bi₂O₃ nanowire samples using a straightforward solvothermal method. Electrocatalytic measurements revealed that the OER performance of these multi-metal doped Bi₂O₃ nanowires were significantly surpassed that of undoped Bi₂O₃ samples. Specifically, the CoFeNiMn-Bi₂O₃-PMA nanowires achieve a current density of 10 mA cm⁻² with an overpotential of merely 285 mV in a 1 M KOH solution, and a Tafel slope of 66 mV dec⁻¹. Through comprehensive characterization and electrocatalytic assessments, we determined that the enhanced OER activity of the CoFeNiMn-Bi₂O₃-PMA nanowires can be attributed to the synergistic effects of Co, Fe, Ni, and Mn elements. Notably, intense electronic interactions among these metal elements led to an elevated concentration of high-oxidation-state cations, such as Co³⁺ and Fe³⁺, along with increased oxygen vacancies. These features collectively augmented the number of reactive sites on the sample surface. Furthermore, stability tests indicated that the CoFeNiMn-Bi₂O₃-PMA nanowires exhibited robust stability, with only a marginal overpotential increase observed during 8 h of chronopotentiometry measurement at a current density of 50 mA cm⁻². This work confirms the efficacy of a simple modification process involving multi-metal doping, designed to enhance the performance of one-dimensional nanowire electrocatalysts, which provide a valuable reference for future research aimed at developing non-noble metal-based electrocatalysts.