Atomically Dispersed Iron Regulating Electronic Structure of Iron Atom Clusters for Electrocatalytic H₂ O₂ Production...

The integration of highly active single atoms (SAs) and atom clusters (ACs) into an electrocatalyst is critically important for high-efficiency two-electron oxygen reduction reaction (2e^- ORR) to hydrogen peroxide (H₂ O₂ ). Here we report a tandem impregnation-pyrolysis-etching strategy to fabricate the oxygen-coordinated Fe SAs and ACs anchored on bacterial cellulose-derived carbon (BCC) (FeSAs/ACs-BCC). As the electrocatalyst, FeSAs/ACs-BCC exhibits superior electrocatalytic activity and selectivity toward 2e^- ORR, affording an onset potential of 0.78 V (vs. RHE) and a high H₂ O₂ selectivity of 96.5 % in 0.1 M KOH. In a flow cell reactor, the FeSAs/ACs-BCC also achieves high-efficiency H₂ O₂ production with a yield rate of 12.51±0.18 mol g_cat ^-1  h^-1 and a faradaic efficiency of 89.4 %±1.3 % at 150 mA cm^-2 . Additionally, the feasibility of coupling the produced H₂ O₂ and electro-Fenton process for the valorization of ethylene glycol was explored in detail. The theoretical calculations uncover that the oxygen-coordinated Fe SAs effectively regulate the electronic structure of Fe ACs which are the 2e^- ORR active sites, resulting in the optimal binding strength of *OOH intermediate for high-efficiency H₂ O₂ production.