光催化
材料科学
分解水
芴酮
载流子
共价键
光化学
共价有机骨架
氧气
析氧
化学工程
光催化分解水
氢
制氢
纳米技术
光电子学
催化作用
化学
物理化学
复合材料
有机化学
电化学
聚合物
电极
芴
多孔性
工程类
作者
Rongchen Shen,Chaochao Qin,Lei Hao,Xiuzhi Li,Peng Zhang,Xin Li
标识
DOI:10.1002/adma.202305397
摘要
Direct photocatalytic hydrogen and oxygen evolution from water splitting is an attractive approach for producing chemical fuels. In this work, a novel fluorenone-based covalent organic framework (COF-SCAU-2) is successfully exfoliated into ultrathin three-layer nanosheets (UCOF-SCAU-2) for photocatalytic overall water splitting (OWS) under visible light. The ultrathin structures of UCOF-SCAU-2 greatly enhance carrier separation, utilization efficiency, and the exposure of active surface sites. Surprisingly, UCOF-SCAU-2 exhibits efficient photocatalytic OWS performance, with hydrogen and oxygen evolution rates reaching 0.046 and 0.021 mmol h-1 g-1 , respectively, under visible-light irradiation, whereas bulk COF-SCAU-2 shows no activity for photocatalytic OWS. Charge-carrier kinetic analysis and DFT calculations confirm that reducing the thickness of the COF nanosheets increases the number of accessible active sites, reduces the distance for charge migration, prolongs the lifetimes of photogenerated carriers, and decreases the Gibbs free energy of the rate-limiting step compared to nonexfoliated COFs. This work offers new insights into the effect of the layer thickness of COFs on photocatalytic OWS.
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