Chinese Journal of Catalysis ›› 2025, Vol. 79: 174-185.DOI: 10.1016/S1872-2067(25)64849-2

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Na2CO3-assisted synthesis of Na-doped crystalline/amorphous g-C3N4 S-scheme homojunction photocatalyst for enhanced H2O2 production

Lihong Tana, Xinhe Wua,*(), Jiachao Xua, Mahmoud Sayedb,c,*(), Guohong Wanga,*()   

  1. aHubei Key Laboratory of Pollutant Analysis and Reuse Technology, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002, Hubei, China
    bLaboratory of Solar Fuel, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China
    cChemistry Department, Faculty of Science, Fayoum University, Fayoum 63514, Egypt
  • Received:2025-08-05 Accepted:2025-08-25 Online:2025-12-05 Published:2025-10-27
  • Contact: Xinhe Wu, Mahmoud Sayed, Guohong Wang
  • Supported by:
    National Natural Science Foundation of China(22302061);National Natural Science Foundation of China(22578106);National Natural Science Foundation of China(W2433135);National Natural Science Foundation of China(22402126)

Abstract:

The construction of crystalline/amorphous g-C3N4 homojunctions presents a versatile strategy to obtain all-organic homojunction photocatalysts with better interface matching and lower interface charge carrier movement resistance for optimized photocatalytic activity. However, the process entails a complex multi-step workup, which compromises its feasibility. To overcome this challenge, this work provided an innovative Na2CO3-induced crystallinity modulation strategy to construct a Na-doped crystalline/amorphous g-C3N4 S-scheme homojunction photocatalyst in a single step. The approach involves the initial pre-assembling of melamine and cyanuric acid molecules, and subsequent introduction of Na2CO3 before the calcination. Na2CO3 plays key roles to induce in-situ crystallinity modulation during the calcination and as a source for Na-doping. The prepared g-C3N4 S-scheme homojunction photocatalyst demonstrated a prominent H2O2-production rate of 444.6 μmol·L-1·h-1, which is 6.1-fold higher than that of bulk g-C3N4. The enhanced activity was attributed to the synergistic effect of charge carrier separation induced by the S-scheme homojunction system, and the optimized interfacial H2O2 generation kinetics. The latter was fostered by the Na-doping. This study provides an innovative approach for the one-step construction of g-C3N4 S-scheme homojunction and its integration in photocatalytic applications.

Key words: Photocatalysis, S-scheme homojunction, Crystalline/amorphous g-C3N4, Crystallinity modulation, H2O2 production