Gradient Surface Gallium-Doped Hematite Photoelectrode for Enhanced Photoelectrochemical Water Oxidation.

Wang, Zeyuan; Wu, Linxiao; Cheng, Jinshui; Chen, Hao; Luo, Jingshan · Nano Lett · 2025

basic_science · Level V

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Abstract

Hematite is a promising material for photoelectrochemical (PEC) water oxidation, but its photocurrent is limited by bulk charge recombination and poor oxidation kinetics. In this study, we report a high-performance Fe<sub>2</sub>O<sub>3</sub> photoanode achieved through gradient surface gallium doping, utilizing a Ga<sub>2</sub>O<sub>3</sub> overlayer on FeOOH precursors via atomic layer deposition (ALD) and co-annealing for Ga diffusion. The Ga-doped layer passivates surface states and modifies the band structure, creating a built-in electric field that enhances the charge separation efficiency. Following the electrodeposition of CoFeO<sub><i>x</i></sub> as a cocatalyst, the resulting CoFe-Ga:Fe<sub>2</sub>O<sub>3</sub> photoanode exhibited a notable negative shift in onset potential by approximately 100 mV, a high photocurrent density of 2.6 mA cm<sup>-2</sup> at 1.23 V versus RHE, and excellent long-term PEC stability over 40 h. This work presents an effective strategy for enhancing the PEC performance of photoelectrodes through advanced surface coatings.