复旦大学乔明华团队报道了聚合物氮化碳定制剥离用于光催化生成H₂O₂及O₂活化介导的CH₄增值。相关研究成果发表在2024年2月20日出版的《德国应用化学》。

块体C₃N₄（BCN）剥离成超薄层状结构暴露内部活性位点和加速电荷分离和传输来提高光催化效率的有效策略。

该文中，研究人员报道了一种新的硝酸根阴离子嵌入-分解（NID）策略，该策略可有效地将BCN剥离为具有定制厚度的几层C₃N₄（fl-CN），直至双层。该策略仅涉及在稀释的HNO₃水溶液中对BCN进行水热处理，然后在不同温度下热解。硝酸根阴离子的分解不仅剥离BCN并改变能带结构，而且将氧物种结合到fl-CN上，这有利于O₂的吸附，从而有利于相关的化学过程。

在可见光照射下的光催化O₂还原中，最佳fl-CN-530催化剂上的H₂O₂产率为952μmol g^–1 h^–1，是BCN的8.8倍。更重要的是，在全电弧照射下，在没有空穴清除剂的情况下，CH₄可以被现场形成的H₂O₂和活性氧物种光催化氧化，产生附加值的C1含氧化合物，其高选择性为99.2%，在无金属的C₃N₄基光催化剂中创下1893μmol g^-1 h^-1的高产率。

附：英文原文

Title: Tailored Exfoliation of Polymeric Carbon Nitride for Photocatalytic H2O2 Production and CH4 Valorization Mediated by O2 Activation

Author: Bo Feng, Yanan Liu, Kun Wan, Sijie Zu, Yan Pei, Xiaoxin Zhang, Minghua Qiao, Hexing Li, Baoning Zong

Issue&Volume: 2024-02-20

Abstract: The exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation–decomposition (NID) strategy that is effective in peeling off BCN into few-layer C3N4 (fl-CN) with tailored thickness down to bi-layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl-CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl-CN-530 catalyst is 952 μmol g–1 h–1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on-site formed H2O2 and active oxygen species to generate value-added C1 oxygenates with high selectivity of 99.2% and record-high production rate of 1893 μmol g1 h1 among the metal-free C3N4-based photocatalysts.

DOI: 10.1002/anie.202401884

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202401884