Band Gap Tuning of Covalent Triazine‐Based Frameworks through Iron Doping for Visible‐Light‐Driven Photocatalytic Hydrogen Evolution

Abstract Photocatalytic hydrogen energy production through water splitting paves a promising pathway for alleviating the increasingly severe energy crisis. Seeking affordable, highly active, and stable photocatalysts is crucial to access the technology in a sustainable manner. Herein, a trivalent iron‐doped covalent triazine‐based framework (CTF‐1) was elaborately designed in this study to finely tune the band structure and photocatalytic activity of CTF‐1 for H 2 production. With optimal doping amount, Fe 10 /CTF‐1 exhibited a satisfying H 2 production activity of 1460 μmol h −1 g −1 , corresponding to 28‐fold enhancement compared with pure CTF‐1. The Fe 3+ doping is responsible for a remarkedly broadened visible‐light adsorption range, improved reduction ability and inhibited electron–hole recombination of CTF‐1. Specifically, the doped Fe 3+ could serve as photocatalytically active center and “electron relay” to accelerate charge separation and transformation. This study offers a feasible strategy to validly design and synthesize CTF‐based photocatalytic materials to efficiently utilize solar energy.