LAUSR

Electrosynthesis of H2 O2 is a promising alternative to the anthraquinone oxidation process because of its low energy utilization and cost-effectiveness. Heteroatom-doped carbons-based catalysts have been widely developed for H2 O2 synthesis. However, their doping degree, defective degree, and location of active sites are difficult to be preciously controlled at molecular level. Herein, a dioxin-linked covalent organic framework (COF) is used as the template to preciously construct different metal-N2 sites along the porous walls for H2 O2 synthesis. By tuning the metal centers, the catalyst with Ca-N2 sites enables to catalyze H2 O2 production with selectivity over 95% from 0.2 to 0.6 V versus RHE, while the H2 O2 yields for Co sites or Ni sites are 20% and 60% in the same potential range. In addition, the turnover frequency (TOF) values for Ca-N2 sites are 11.63 e-1 site-1 s-1 , which are 58 and 20 times higher than those of Co and Ni sites (0.20 and 0.57 e-1 site-1 s-1 ). The theoretical calculations further reveal that the OOH* desorption on Ca sites is easier than those on Co or Ni sites, and thus catalyzes the oxygen reduction reaction in the 2e- pathway with high efficiency.