Synergistic effects of feni bimetal-doped biochar on oxygen evolution reaction kinetics: A one-step, low-temperature pyrolysis approach

As the hydrogen energy sector progresses, water electrolysis technology played a crucial role in producing green hydrogen. A major challenge in this endeavor lied in the oxygen evolution reaction (OER), where the overpotential has consistently been high leading to an increase in the energy demand. This study developed a one-step pyrolysis technique to transform metal-supported biomass into FeNi/NC catalysts having enhanced crystallinity and defect sites. This process without activation step using strong acids or bases reduced the operational procedures and the treatment of intermediate products, which reduced the technical difficulty. As the pyrolysis temperature increases, the metal ions in the biochar gradually formed stable metal oxides, which catalyze the alkaline OER and markedly boosted catalytic efficiency. Crucially, the abundance of lattice oxygen and oxygen vacancies in the catalyst played a key role in enhancing the OER kinetics. Notably, the catalyst pyrolyzed at 750 °C demonstrated good performance, with an overpotential of 270 mV at a concentration of 10 mA cm⁻² of the density of current, which was superior to RuO₂(η₁₀=315 mV) and IrO₂(η₁₀=300 mV). Overall, this study reported an approach for the fabrication of high-performance OER catalysts and the strategic utilization of biomass resources for application in clean energy technologies.