Anchoring Redox Mediator on COFs for Efficient Solar to Hydrogen Conversion
Haijun Hu, Xiaodong Sun, Yali Ma, Hui Li, Wei Zhang, Hua Fan, Hongwei Huang, Tianyi Ma
Abstract
Abstract To address severe carrier recombination in Z‐scheme heterojunctions, redox mediators such as IO 3 − / I− or Fe 3 ⁺/Fe 2 ⁺ are often introduced, yet their dispersion in solution causes instability, low electron transport efficiency and side reactions. Herein, an innovative Fe‐coordinated 2D Z‐scheme heterojunction composed of TpPa‐1‐COF (TP1C) and Bi 2 WO 6 (BWO) is developed for efficient photocatalytic H 2 production. Unlike traditional indirect Z‐scheme heterojunctions, the Fe 3+ /Fe 2+ mediator is firmly anchored on the skeleton of COFs, thus enhancing recyclability, charge migration and long‐lasting stability, which is supported by extended X‐ray absorption fine structure (EXAFS) and a range of electrochemical tests. In addition, the formation of 2D Z‐scheme heterojunctions not only retains high redox properties but also provides abundant active sites for photocatalytic reactions. Consequently, the photocatalytic H 2 production rate of 25% BWO/Fe/TP1C reaches up to 6.31 mmol·g −1 ·h −1 without the addition of co‐catalysts, being about 28.68 times as high as that of pure COFs and 2.3 folds over that of 25% BWO/TP1C, exceeding a host of COF‐based photocatalysts. The findings of this research highlight the potential of novel indirect Z‐scheme heterojunctions for advanced photocatalytic applications, offering a new pathway to overcome the limitations of traditional COF‐based systems in hydrogen production.