Synergistic Effect of a Bi₂MoO₆/g-C₃N₄ Composite for Highly Selective Electrocatalytic Oxygen Reduction to Produce...

The design of high-performance electrocatalysts for the environmentally friendly synthesis of hydrogen peroxide (H₂O₂) via a two-electron oxygen reduction reaction (2e^- ORR) method, which presents a promising alternative to the traditional anthraquinone process, remains a significant challenge. Thus, there is an urgent demand for the development of highly efficient and selective electrocatalysts for H₂O₂ generation. Herein, a cost-effective, precious metal-free Aurivillius oxide and heteroatom-based carbon composite material, i.e., Bi₂MoO₆/g-C₃N₄ (BMO/gCN), synthesized by the solvothermal method, is demonstrated for the 2e^- ORR. The optimized composite catalyst (1:1 BMO/gCN) exhibits superior H₂O₂ selectivity of 86-97% at a wide potential range of 0.2-0.6 V versus RHE and electron transfer number (n) values between 2.06 and 2.27 in 0.1 M KOH electrolyte. The synthesized electrocatalyst exhibits consistent H₂O₂ selectivity, as demonstrated by a 50 h durability test at 0.3 V versus RHE. The Faradaic efficiency and H₂O₂ yield rate reached a maximum of 98% and 860 mmol g^-1 h^-1, respectively, at 0.3 V versus RHE after 5 h of electrocatalysis for H₂O₂ production. To further support the experimental finding, density functional theory calculations using the Perdew-Burke-Ernzerhof functional with Grimme's D3 dispersion correction are performed. The BMO/gCN composite structure exhibits the favorable Gibbs free energy profile for the 2e^- ORR pathway, with spontaneous OOH* formation (ΔG = -1.00 eV) and highly exothermic H₂O₂ generation (ΔG = -1.28 eV), confirming its superior catalytic activity and selectivity toward H₂O₂ production. This work presents a fresh approach to an efficient electrocatalyst for 2e^- ORR.