Three Birds, One‐Stone Strategy for Hybrid Microwave Synthesis of Ta and Sn Codoped Fe 2 O 3 @FeTaO 4 Nanorods for Photo‐Electrochemical Water Oxidation

A “three birds, one stone” strategy is proposed to enhance the performance of hematite photoanode for photoelectrochemical water splitting. One‐pot hybrid microwave synthesis of Ta and Sn codoped Fe 2 O 3 @FeTaO 4 core–shell nanorods on F:SnO 2 substrate achieves three synergetic effects simultaneously: i) core–shell heterojunction formation to alleviate the significant electron–hole recombination; ii) preserved morphology of small‐diameter nanorods to provide a short hole diffusion distance; and iii) Ta and Sn codoping to enhance the electrical conductivity. These effects are not possible with conventional high temperature thermal synthesis in a furnace. As a result, core–shell Fe 2 O 3 @FeTaO 4 electrode with FeOOH cocatalyst achieves a photocurrent density of 2.86 mA cm −2 at 1.23 V RHE under AM 1.5 G simulated sunlight (100 mW cm −2 ), which is ≈2.4 times higher than that of bare hematite (1.17 mA cm −2 ). In addition, the FeOOH/Fe 2 O 3 @FeTaO 4 electrode exhibits a high surface charge separation efficiency of ≈85% and a modest bulk charge separation efficiency of ≈24%.