Identifying the two-electron oxygen reduction mechanism on BC3 site in Cl- -containing electrolytes

The electrochemical synthesis of H2O2 has great potential for applications in the treatment of environmental pollution and energy, but the toxic effect of Cl- on the active sites of catalysts has severely limited the application of this technology in these fields. Developing efficient non-metal-doped catalysts represents an effective strategy to address this issue. Although B-doped carbon materials have demonstrated excellent ORR activity, the understanding of the ORR mechanism on B surface sites remains highly controversial, particularly in seawater electrolytes. The influence of Cl- adsorption behavior on the catalytic reaction center mechanism is still unknown. In this paper, catalysts containing the BC3 structure were successfully prepared with an H2O2 yield of 3.55 mol/ (gcat h) in simulated seawater. The DFT results demonstrated that BC3 functions as a 2e- ORR active site, and the presence of Cl- does not poison it. Instead, it promotes the hydrogenation process of *OOH on its surface, further enhancing its ORR performance. The results provide clarity on how the Cl- of the catalytic environment affects the ORR performance and pathway selectivity of non-metallic B-sites. Additionally, the results offer valuable insights for designing electrocatalysts in complex environments.