Identifying Activity Trends for the Electrochemical Production of H2O2 on M-N-C Single-Atom Catalysts Using Theoretical Kinetic Computations

catalysts (SACs) have shown high potential to generate H2O2 through the two-electron oxygen reduction reaction (2e??? ORR) pathway in an acidic electrolyte. However, there is still a lack of effective kinetic computation to reveal M???N???C SACs??? intrinsic catalytical performance toward 2e??? ORR. Here, we combine the experimental and computational efforts to study the 2e??? ORR activity trends of M???N???C SACs (M = Co, Fe, and Mn). The experimental results show that Co???N???C and Mn???N???C SACs favor the 2e??? ORR pathway but Fe???N???C SAC favors the 4e??? ORR pathway. Using systematic kinetic calculation, we demonstrated that desorption of HOOH* or H2O* was a real determining step of the ORR pathway on M???N???C SACs. The difference in the desorption energy between H2O* and HOOH* reaction oxygen intermediates (EH2O* ??? EHOOH*) on a metal active center is a credible descriptor to illustrate and predict the H2O2 selectivity of M???N???C SACs. The predicted high H2O2 selectivity of Ni???N???C SACs from the descriptor is consistent with the experimental results. This study clarifies the mechanism of ORR on M???N???C SACs and identifies the determining factors of the ORR pathway, providing new insights into the rational design of high-H2O2-selectivity M???N???C SACs.

Automated summary

The catalytic activity trend of metal atom-loaded solid nitride catalysts was investigated, and it was found that different catalysts prefer different pathways for the oxygen reduction reaction. The key factors in the reaction steps on the catalysts were revealed through systematic kinetic calculation.