An efficient Sb-SnO₂-supported IrO₂ electrocatalyst for the oxygen evolution reaction in acidic medium

Polymer (acidic) electrolyte membrane water electrolysis suffers from insufficient catalyst activity, high cost of noble metal, and unsatisfactory durability, due to the sluggish reaction kinetics of oxygen evolution reaction and poor stability of catalysts under harsh operating environments. Aiming to enhance the utilization and durability of noble metals, a mesoporous Sb-doped SnO₂ material with high surface area and conductivity was synthesized via soft-template method to support IrO₂ catalyst. Physical characterization reveals that the as-prepared composite exhibits a rough morphology with the weak crystallinity IrO₂ upper layer covering the rutile SnO₂ crystalline phase. Electrochemical test for the IrO₂-loading-dependant activity finds that both the area-free activity and mass-specific current on the 31 wt% sample are the optimal, meaning the excellent dispersion effect coming from the mesoporous Sb-SnO₂ support and the synergy between the catalytic particles and Sb dopant. In addition, the enhancement in mass transfer efficiency and conductivity coming from the porous, IrO₂-covered cross-linked morphology and the support-active component interaction, the supported IrO₂ with 50 wt% loading marks the maximum normalized charge (227 C g⁻¹ IrO₂) and the highest apparent current at 1.75 V. What is more, this composite catalyst with the noble metal oxide coating is much more durable during continuous oxygen evolution procedure under a constant potential of 1.6 V because of the anchor effect from the carrier on the catalyst and a protective effect from the noble metal layer on the non-acid-tolerant support.