Three Birds, One-Stone Strategy for Hybrid Microwave Synthesis of Ta and Sn Codoped Fe2O3@FeTaO4 Nanorods for Photo-Electrochemical Water Oxidation

Abstract

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 Fe2O3@FeTaO4 core–shell nanorods on F:SnO2 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 Fe2O3@FeTaO4 electrode with FeOOH cocatalyst achieves a photocurrent density of 2.86 mA cm−2 at 1.23 VRHE 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/Fe2O3@FeTaO4 electrode exhibits a high surface charge separation efficiency of ≈85% and a modest bulk charge separation efficiency of ≈24%.