Efficient Proton Transfer and Charge Separation within Covalent Organic Frameworks via Hydrogen-Bonding Network to Boost H 2 O 2 Photosynthesis.

Photocatalytic synthesis based on the oxygen reduction reaction (ORR) has shown great promise for H 2 O 2 production. However, the low activity and selectivity of 2e - ORR result in a fairly low efficiency of H 2 O 2 production. Herein, we propose a strategy to enhance the proton-coupled electron transfer (PCET) process in covalent organic frameworks (COFs), thereby significantly boosting H 2 O 2 photosynthesis. We demonstrated that the construction of a hydrogen-bonding network, achieved by anchoring the H 3 PO 4 molecular network on COF nanochannels, can greatly improve both proton conductivity and photogenerated charge separation efficiency of COFs. Thus, COF@H 3 PO 4 exhibited superior photocatalytic performance in generating H 2 O 2 without sacrificial agents, with a solar-to-chemical conversion efficiency as high as 0.69%. Results indicated that a much more localized spatial distribution of energy band charge density on COF@H 3 PO 4 led to efficient charge separation, and the small energy barrier of the rate-limiting step from *OOH to H 2 O 2 endowed COF@H 3 PO 4 with higher 2e - ORR selectivity.