Tuning reactive metal-support interaction (RMSI) is a promising approach to optimizing catalytic active sites via the electronic, geometric and compositional effects. However, the RMSI is commonly conducted on the reducible oxides via a high-temperature reaction (> 550^oC). One team from Department of Materials Science and Engineering, Peking University has gained insight into the low-temperature (< 0^oC) RMSI effect between noble metal single atoms (MSAs) and N-vacancy-rich g-C₃N₄ via the icing-assisted in-situ photocatalytic reduction method (Figure a). The results reveal that the rich N vacancies in g-C₃N₄ produce an obvious electron-deficient effect, which greatly enhances the RMSI between Pt single atom (PtSA) and g-C₃N₄. This strong RMSI not only leads to the highest PtSA coverage density of 0.35 mg m^-2 reported to date in carbon-based materials, but also contributes to the outstanding H₂-evolution activity of 174.5 mmol gPt^-1 h^-1 relative to those on the electron-rich g-C₃N₄. The structure simulation reveals that the RMSI can not only stabilize the PtSA on the electron-deficient g-C3N4 via the strong chemical bond between PtSA and the two-coordinated C (C_2C) sites caused by the N vacancies, but also promises the PtSA with an optimized electronic and geometric structures for capturing photogenerated electrons and producing H₂, respectively.

With the support of 1W1B beamline of Beijing Synchrotron Radiation Facility (BSRF), EXAFS spectra of Pt L3-edge were obtained to illustrate the coordination structure of Pt single atoms. The Pt single atoms tend to be stabilized in the N vacancy site by forming Pt-C bonds (Figure b), which agrees with the theoretical model of PtSA on N vacancies-modified g-C₃N₄. This Pt-C interaction enables the PtSA with a more negative 5d states, which contributes to the RMSI between PtSA and g-C₃N₄.

This research opens an interesting strategy for designing and making single atom catalysts on the photocatalyst with low thermostability. Exploring the RMSI effect between MSAs and photocatalyst will be beneficial to the development of high-performance photocatalyst materials. 1W1B beamline will be significant for understanding the RMSI. Their research has been published on November 15th, 2018 in Nano Energy.

(a) Schematic illustration of the icing-assisted in-situ photocatalytic reduction method for preparing the supra-high-density PtSAs-loaded g-C₃N₄. Scale bar: 2 nm. (b) Pt L3-edge EXAFS spectra at R space.

Article：

Peng Zhou, Fan Lv, Na Li, Yelong Zhang, Zijie Mu, Yonghua Tang, Jianping Lai, Yuguang Chao, Mingchuan Luo, Fei Lin, Jinhui Zhou, Dong Su and Shaojun Guo* Strengthening reactive metal-support interaction to stabilize high-density Pt single atoms on electron-deficient g-C3N4 for boosting photocatalytic H₂ production. Nano Energy, 56(2019), 127–137.