Atomically Dispersed Iron Regulating Electronic Structure of Iron Atom Clusters for Electrocatalytic H2O2 Production and Biomass Upgrading

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 (H2O2). 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 H2O2 selectivity of 96.5 % in 0.1 M KOH. In a flow cell reactor, the FeSAs/ACs-BCC also achieves high-efficiency H2O2 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 H2O2 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 H2O2 production.

Automated summary

The integration of oxygen-coordinated Fe single atoms and atom clusters using a tandem impregnation-pyrolysis-etching strategy shows superior electrocatalytic activity and selectivity towards two-electron oxygen reduction reaction (2e(-) ORR) to hydrogen peroxide (H2O2). The FeSAs/ACs-BCC electrocatalyst exhibits high-efficiency H2O2 production and coupling with electro-Fenton process for ethylene glycol valorization.