Efficient Proton Transfer and Charge Separation within Covalent Organic Frameworks via Hydrogen-Bonding Network to Boost H<sub>2</sub>O<sub>2</sub> Photosynthesis
Yan Lin, Juncong Zou, Xin Wu, Shehua Tong, Qiuya Niu, Shanying He, Shenglian Luo, Chunping Yang
Abstract
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.