Artificial photocatalytic synthesis of H2O2 using water and oxygen, as a spotless method, has aroused widespread attention. Given the abundance of seawater, the utilization of seawater to photo-produce H2O2 can not only mitigate the problem of fresh water resource shortage, but also greatly reduce the cost of reaction system process. However, the salt in seawater can consume the photogenerated carriers, cause undesirable side reactions on the surface of the catalysts, and even deactivate the catalysts, which severely limits the industrialization process of H2O2 production by sunlight. Up to date, it's still a challenge to produce H2O2 in seawater by photocatalysis. In addition，the current researches on the charge in the photocatalysis process cannot provide the detailed information of the charge variation, which is not conducive to in-depth understanding and analysis of the catalytic mechanism.
Recently, the research groups of Prof. Zhenhui Kang, Mingwang Shao and Yang Liu from FUNSOM of Soochow University, discovered the electron sink effect of carbon dots (CDs) using the self-designed and self-developed in-situ transient photovoltage (TPV) interface dynamics system for the first time, and revealed the enhancement mechanism of salts to the electron sink effect. Based on the salt-protective electron sink effect of CDs, a metal-free photocatalyst (PM-CDs-30) was designed and synthesized. At the same time, the thermal-kinetic model was constructed with the assistance of in-situ TPV system. Based on this model, the vital information of the reaction rate, reaction mechanism, catalytic kinetics and optimal reaction conditions of the catalyst were obtained, the enhancement of electron sink effect by salts in the composite catalyst was studied, and the accurate prediction of the catalyst and catalytic reaction was realized. The experiment results showed that the catalyst PM-CDs-30 exhibits enhanced photocatalytic activity in seawater, and the synthesis rate of H2O2 can reach 1776 μmol/g/h in real seawater, which is much higher than the yield in pure water. This work is published in Nature Communications with the title “A metal-free photocatalyst for highly efficient hydrogen peroxide photoproduction in real seawater”.
The in-situ TPV system can obtain the information of the catalysis mechanism and the charge dynamics at the interface. At present, the test results from this TPV system, as important experimental data, have supported a number of scientific researches, which have been published in Nature Communications, Angewandte Chemie International Edition, Nano Letters, Applied Catalysis B-Environmental and so on.
The first author, Dr. Qingyao Wu, is co-supervised by Prof. Mingwang Shao and Zhenhui Kang.
Link to Paper: https://www.nature.com/articles/s41467-020-20823-8
Editor: Danting Xiang