Dual-Isolation Effect of Bismuth in Non-Noble BiNi Alloys for Enhanced Performance in H2O2 Electrosynthesis

Abstract

Noble-metal alloys are high-efficiency two-electron oxygen reduction reaction (2e^– ORR) catalysts for the electrochemical production of H₂O₂. However, the development of noble-metal alloys for H₂O₂ production is still in a bottleneck period due to their high cost, toxicity, low atom utilization, and limited reactivity. To solve these dilemmas of noble-metal alloys, developing non-noble alloys can be an alternative. Herein, non-noble BiNi alloys with a uniform diameter of ∼11 nm supported on carbon nanosheets (BiNi/C) are synthesized by a hydrothermal-pyrolysis method. The BiNi/C material exhibits high 2e^– ORR performance with an onset potential of 0.76 V vs RHE and a selectivity of ∼98% in 0.1 M KOH. The H-cell tests deliver a high H₂O₂ yield of ∼17 mM within 2 h at 0.4 V vs RHE. The synthesized H₂O₂ is then used in a fixed-bed Fenton process, and the degradation efficiencies of RhB and BPA maintain at 100% and ∼95% within 10 h, respectively. Theoretical calculations reveal that Bi can regulate the electronic structure of Ni in BiNi alloys through the “dual-isolation” effect of physical and electronic isolation. The adsorption energy for *OOH is thus deceased, and side-on adsorption of *OOH on Ni sites is achieved. Furthermore, the Bi atom itself with the lowest overpotential can also serve as a high active site for H₂O₂ generation due to the dual-isolation effect. Our study provides guidance for the synthesis of non-noble alloy catalysts for 2e^– ORR with high activity and selectivity.