Bimetallic core-based cuboctahedral core–shell nanoclusters for the formation of hydrogen peroxide (2e− reduction) over water (4e− reduction): role of core metals

Abstract

The design of an efficient and selective catalyst for hydrogen peroxide (H₂O₂) formation is highly sought due to its industrial importance. As alternatives to a conventional Pd–Au alloy-based catalyst, three cuboctahedral core–shell nanoclusters (Au₁₉@Pt₆₀, Co₁₉@Pt₆₀ and Au₁₀Co₉@Pt₆₀ NCs) have been investigated. Their catalytic activities toward H₂O₂ formation have been compared with that of pure Pt cuboctahedral NC (Pt₇₉). Much attention has been devoted to thermodynamic and kinetic parameters to find out the feasibility of the two-electron (2e⁻) over the four-electron (4e⁻) oxygen reduction reaction (ORR) to improve the product selectivity (H₂O vs. H₂O₂). Elementary steps corresponding to H₂O₂ formation are significantly improved over the Au₁₀Co₉@Pt₆₀ NC catalyst compared with the pure core–shell NCs and periodic surface based catalysts. Furthermore, the Au₁₀Co₉@Pt₆₀ NC favours H₂O₂ formation via the much desired Langmuir–Hinshelwood mechanism. The potential-dependent study shows that the H₂O₂ formation is thermodynamically favourable up to 0.43 V on the Au₁₀Co₉@Pt₆₀ NC and thus the overpotential for the 2e⁻ ORR process is significantly lowered. Besides, the Au₁₀Co₉@Pt₆₀ NC is highly selective for H₂O₂ formation over H₂O formation.