Effect of the Second-Shell Coordination Environment on the Performance of P-Block Metal Single-Atom Catalysts for the Electrosynthesis of Hydrogen Peroxide

Hydrogen peroxide (H2O2) is an important chemical with a diverse range of industrial applications in chemical synthesis and medical disinfection. The traditional anthraquinone oxidation process, with high energy consumption and complexity, is being replaced by cost-effective and environmentally friendly alternatives. In order to explore suitable catalysts for the electrocatalytic synthesis of H2O2, the stability of B,N-doped graphene loaded with various p-block metal (PM) single atoms (i.e., PM-NxBy: x and y represent the number of atoms of N and B, respectively) and the effects of different numbers and positions of B dopants in the second coordination shell on the catalytic performance were studied by density functional theory (DFT) calculations. The results show that Ga-N4B6 and Sb-N4B6 exhibit enhanced stability and 2e(-) oxygen reduction reaction (ORR) activity and selectivity. Their thermodynamic overpotential eta values are 0.01 V, 0.03 V for Ga-N4B6's two configurations and 0.02 V, 0 V for Sb-N4B6's two configurations. Electronic structure calculations indicate that the PM single atom adsorbs OOH* intermediates and transfers electrons into them, resulting in the activation of the O-O bond, which facilitates the subsequent hydrogenation reaction. In summary, Sb-N4B6 and Ga-N4B6 exhibit extraordinary 2e(-) ORR performance, and their predicted activities are comparable to those of known outstanding catalysts (such as PtHg4 alloy). We propose effective strategies on how to enhance the 2e(-) ORR activities of carbon materials, elucidate the origin of the activity of potential catalysts, and provide insights for the design and development of electrocatalysts that can be used for H2O2 production.