Ir/TiO ₂ Heterojunctions with in Situ Defects and Surface Plasmon Resonance: Chloride‐Resistant Catalyst for the Photocatalytic Hydrogen Evolution from Seawater

Photocatalytic seawater splitting for hydrogen production emerges as a promising sustainable approach to alleviate energy crises and global warming. However, its practical application is critically hindered by Cl – ‐induced catalyst corrosion and poor long‐term stability under harsh high‐salt conditions. Herein, we report a rationally designed photocatalyst comprising Ir nanoclusters uniformly dispersed on the (101) facets of a mesoporous TiO 2 matrix. This design in situ introduces Ti 3+ species and oxygen vacancies within the TiO 2 lattice to extend light absorption. The surface plasmon resonance effect of Ir nanoclusters promotes efficient charge separation at the Ir/TiO 2 heterojunction, suppressing carrier recombination and boosting the utilization efficiency of photocarriers. Moreover, the Ir active sites demonstrate preferential coordination with H + /OH – species through coordination competition, reducing the overpotential for hydrogen evolution reaction, mitigating the competitive chloride oxidation reaction, and ensuring exceptional catalytic stability. Under full‐spectrum light illumination, the 1% Ir/TiO 2 catalyst achieves a hydrogen evolution rate of 0.46 mmol h −1 (46.00 mmol g cat −1 h −1 ) with a remarkable turnover frequency of 1163.38 h −1 . This work establishes an effective strategy for constructing TiO 2 ‐based photocatalysts featuring low noble metal loading, robust Cl – corrosion resistance, and outstanding photocatalytic activity under harsh high‐salt environments, offering a cost‐effective route toward direct solar‐driven hydrogen production from seawater.