J. Mater. Sci. Technol. ›› 2024, Vol. 199: 53-65.DOI: 10.1016/j.jmst.2024.02.048

• Research article • Previous Articles     Next Articles

Pauling-type adsorption of O2 induced by S-scheme electric field for boosted photocatalytic H2O2 production

Shuang Zhoua,1, Da Wena,1, Wei Zhonga, Jianjun Zhangb,*, Yaorong Sua,*, Aiyun Menga,*   

  1. aCollege of New Materials and New Energies, Shenzhen Technology University, Shenzhen 518118, China;
    bLaboratory of Solar Fuel, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, China
  • Received:2024-01-05 Revised:2024-02-01 Accepted:2024-02-04 Published:2024-11-10 Online:2024-11-07
  • Contact: *E-mail addresses: zhangjianjun@cug.edu.cn (J. Zhang), suyaorong@sztu.edu.cn (Y. Su), mengaiyun@sztu.edu.cn (A. Meng)
  • About author:1These authors contributed equally to this work.

Abstract: The effective adsorption of oxygen (O2) molecules over photocatalysts is a critical step in promoting the performance of photocatalytic H2O2 production. However, g-C3N4 usually features a Yeager-type (side-on) adsorption configuration of O2 molecules, which causes the breaking of O-O bonds and severely hinders the H2O2 production activity. Herein, we synthesized an oxygen-vacancy-rich TiO2-x/g-C3N4 step-scheme (S-scheme) heterojunction to regulate the oxygen adsorption configuration and improve the 2e- ORR selectivity of H2O2 production. In-situ X-ray photoelectron spectroscopy (in-situ XPS) and density functional theory (DFT) calculations reveal that the S-scheme heterojunction is formed between TiO2-x and g-C3N4. The difference between their Fermi levels leads to the electron flow from g-C3N4 to TiO2-x, which increases the electron-deficient sites in g-C3N4. As a result, the cleavage of O-O bonds on the surface of g-C3N4 is avoided and the oxygen adsorption configuration is tuned from Yeager-type to Pauling-type (end-on). Consequently, the photocatalytic H2O2 production rate is dramatically improved to 1780.3 μmol h-1, which is about 5 times higher than that of pristine g-C3N4. This work paves a new way to tailor the oxygen adsorption configuration by rationally designing S-scheme heterojunction photocatalysts.

Key words: S-scheme heterojunction, Hydrogen peroxide production, Pauling-type oxygen adsorption, Femtosecond transient absorption spectroscopy, Two-electron oxygen reduction selectivity