SnO2-supported single metal atoms: a bifunctional catalyst for the electrochemical synthesis of H2O2

On-site hydrogen peroxide (H2O2) production via electrochemical methods, such as two-electron water oxidation reaction (2e-WOR) and two-electron oxygen reduction reaction (2e-ORR), offer an attractive alternative to the anthraquinone oxidation (AO) process. However, for 2e-WOR and 2e-ORR to hold any industrial relevance, inexpensive, stable, highly efficient, selective, and environmentally benign electrocatalysts must be developed. Designing a catalyst to meet such an extensive criterion remains a challenge. Single-atom catalysts (SACs), combining the benefits of heterogenous and homogenous catalysis, have drawn immense attention due to their distinguished catalytic performance. Ergo, we aim towards the exploration of a bifunctional SAC material capable of catalyzing the 2e-WOR and 2e-ORR to produce H2O2. Through density functional theory (DFT) calculations we investigate the catalytic activity, selectivity, and stability of SnO2-supported SACs. Considering 16 different single metal atoms, various promising candidates were identified. Particularly, Mn, Ti and Fe were found to be markedly active and selective 2e-WOR catalysts and W for the 2e-ORR. This work highlights the immense potential of bifunctional systems; a route towards increasing H2O2 yields while simultaneously minimizing manufacturing complexity and cost.