关键词: 石墨相氮化碳, 超薄纳米片, 碳空位, 可见光, 过氧化氢

Abstract:

Photocatalytic production of hydrogen peroxide (H₂O₂), as a green and sustainable technology, has the advantages of clean and pollution-free, safety, low energy consumption and low cost compared with the anthraquinone method commonly used in industry. Graphitic phase carbon nitride (g-C₃N₄), as an inorganic nonmetallic material, is a promising H₂O₂ producing photocatalyst. However, bulk g-C₃N₄ suffers from severe photogenerated electrons-holes complexation and weak photogenerated charge transfer ability, resulting in its low photocatalytic H₂O₂ production efficiency. In order to improve the photocatalytic H₂O₂ production activity of g-C₃N₄, ultrathin g-C₃N₄ nanosheets containing carbon vacancies (CNS₅₈₀) were prepared by simple sequential two-step high-temperature calcination in this paper, and the structure and morphology, light absorption properties and electrochemical properties of photocatalysts were characterized by XRD, SEM, AFM, ESR, UV-Vis, TPC and EIS. The results showed that the photocatalyst had an ultrathin nanosheet structure with a thickness of about 2.15nm, which could improve the transmission efficiency of photogenerated charge. Meanwhile, the introduced carbon vacancies could capture photogenerated electrons, which would improve its photogenerated electrons-holes separation ability. In the experiment of photocatalytic H₂O₂ production, the H₂O₂ production concentration by CNS₅₈₀via photocatalytic reaction for 6h could reach 0.091mmol/L, which was 4.13 times higher than that of the bulk g-C₃N₄. In addition, the possible mechanism of photocatalytic H₂O₂ production for CNS₅₈₀ was discussed and proposed.

Key words: graphitic phase carbon nitride, ultra-thin nanosheets, carbon vacancy, visible light, hydrogen peroxide