Enhancing photocatalytic hydrogen evolution of carbon nitride through high-valent cobalt active sites in cobalt
Xunhuai Huang1, Guanyu Wu2, Yanhua Song1
1School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, PR China.
Abstract:
The photocatalytic hydrogen (H2) evolution reaction driven by solar energy is one of the most promising methods to alleviate energy and environmental problems. Regrettably, the rapid recombination of photogenerated electrons and hole pairs in semiconductor catalysts leads to low solar energy conversion efficiency. To address this problem, we chose the method of co-catalyst loading. This study uses an in-situ self-assembly growth strategy to load high-valent cobalt sulfide (CoS) onto bulk carbon nitride (BCN) for photocatalytic H2 evolution. The results show that the photocatalytic H2 evolution performance of the optimal ratio of CoS and BCN composite (CoS-BCN(15%)) is 156 times that of BCN. The main reason for the performance improvement is that CoS nanoparticles act as co-catalysts to increase the carrier migration rate. Moreover, CoS nanoparticles contain mixed-valence Co3+/Co2+. During the reaction, high-valence cobalt ions become electron transfer stations, reacting with additional electrons to generate low-valence ions, reducing the recombination of carriers. Additionally, combined experiments and theoretical calculations show that the CoS surface is more conducive to the precipitation of H2 than BCN. This study provides a reference for further exploring the mechanism of action of co-catalysts.
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