Sn-doped Bi2O3 as an efficient and robust electrocatalyst for the oxygen evolution reaction

This work reports a structurally engineered Sn-doped Bi₂O₃ electrocatalyst for the alkaline oxygen evolution reaction (OER). A series of Sn-doped catalysts were synthesized with various doping percentages (0.25 wt % − 1 wt %) over the α-Bi 2 O 3 matrix. They were tested for their application in OER in an alkaline medium (1 M KOH). An overpotential of 335 mV was observed at a current density of 10 mA cm⁻² with a Tafel slope of 74.53 mV/dec for the optimized catalyst (BO1). It is understood that the increased oxygen vacancies after doping have enhanced the catalyst’s OER kinetics. The stability test was conducted for 100 h at a current density of 10 mA in a half-cell configuration. As a low-cost alternative, a Ni(OH) 2 catalyst was tested for the alkaline HER, showing good efficiency. Based on this understanding, an H-type cell was also constructed using the optimized catalyst as the anode and Ni(OH) 2 as the cathode to assess its practical viability, and it showed good stability for 50 h with minimal voltage drop.