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

摘要：

光催化产过氧化氢（H₂O₂）作为一种绿色可持续发展技术，相比于工业上常用的蒽醌法，具有清洁无污染、安全、低能耗及低成本等优点。石墨相氮化碳（g-C₃N₄）作为一种无机非金属材料，是一种很有前景的产H₂O₂光催化剂。然而，块体g-C₃N₄存在光生电子空穴复合严重以及光生电荷迁移能力弱等问题，导致其光催化产H₂O₂效率低。为了提高g-C₃N₄的光催化产H₂O₂活性。本文通过简单的连续两步高温煅烧制备了含有碳空位的超薄g-C₃N₄纳米片（CNS₅₈₀），通过X射线衍射仪、扫描电子显微镜、原子力显微镜、电子顺磁共振仪、紫外可见漫反射、瞬态光电流、电化学阻抗谱测试等对光催化剂进行了一系列的结构形貌、光吸收性能以及电化学性能表征。结果表明，该光催化剂具有超薄纳米片结构，厚度约为2.15nm，可提高光生电荷的传输效率；同时引入的碳空位可捕获光生电子，这将改善其光生电子空穴的分离能力。在光催化产H₂O₂的实验中，CNS₅₈₀光催化反应6h，其产H₂O₂浓度可达到0.091mmol/L，是块体g-C₃N₄的4.13倍。此外，讨论并提出CNS₅₈₀光催化产H₂O₂可能的机理。

关键词: 石墨相氮化碳, 超薄纳米片, 碳空位, 可见光, 过氧化氢