In situ Ion Pumping Anodization to Confine Single‐Atom Fe onto TiO2 Nanotubes for Enhanced Noble‐Metal‐Free Photocatalytic Hydrogen Generation

Abstract Achieving a high dispersity of deposited transition metal is crucial in the anodization preparation of noble‐metal‐free composites for photocatalytic hydrogen generation. Herein, for the first time, an in situ ion pumping anodization method is proposed to confine single‐atom Fe within the spatially ordered structure of anodized TiO 2 nanotubes (TNT), assisted by ferric sodium salt of ethylenediaminetetraacetic acid (EDTA) as an “ion pump” to deliver Fe 3+ toward anodes. Both experimental and theoretical calculations confirm that highly dispersed single‐atom Fe can interact with single‐electron‐trapped oxygen vacancies (SETOV), effectively reducing the oxygen vacancy concentration in TiO 2 nanotubes. This reduction promotes efficient charge carrier separation through the Fe(III)/Fe(II) pathway and enhances hydrogen desorption, ultimately boosting the photocatalytic hydrogen evolution performance.