Monitoring Electron Flow in Nickel Single-Atom Catalysts during Nitrogen Photofixation.

Wang, Qingyu; Xiao, Yu; Yang, Shaokang; Zhang, Yida; Wu, Lihui; Pan, Haibin; Rao, Dewei; Chen, Tao et al. · Nano Lett · 2022

basic_science · Level V

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Abstract

An efficient catalytic system for nitrogen (N<sub>2</sub>) photofixation generally consists of light-harvesting units, active sites, and an electron-transfer bridge. In order to track photogenerated electron flow between different functional units, it is highly desired to develop <i>in situ</i> characterization techniques with element-specific capability, surface sensitivity, and detection of unoccupied states. In this work, we developed <i>in situ</i> synchrotron radiation soft X-ray absorption spectroscopy (<i>in situ</i> sXAS) to probe the variation of electronic structure for a reaction system during N<sub>2</sub> photoreduction. Nickel single-atom and ceria nanoparticle comodified reduced graphene oxide (CeO<sub>2</sub>/Ni-G) was designed as a model catalyst. <i>In situ</i> sXAS directly reveals the dynamic interfacial charge transfer of photogenerated electrons under illumination and the consequent charge accumulation at the catalytic active sites for N<sub>2</sub> activation. This work provides a powerful tool to monitor the electronic structure evolution of active sites under reaction conditions for photocatalysis and beyond.