A promising InGaAsN photoanode protected by multifunctional GaN nanocrystal for efficient photoelectrochemical water splitting

Abstract

Photoelectrochemical (PEC) water splitting is one of the most promising techniques to produce sustainable hydrogen fuels. However, the sluggish oxygen evolution reaction (OER) kinetics and poor stability occurring on photoanodes greatly limit its practical application. In this work, a photoanode semiconductor using high-quality InGaAsN film was innovatively introduced to enhance PEC water oxidation. Further, GaN nanocrystal was deposited on InGaAsN photoanode to accelerate the transportation of photogenerated carriers and improve the photostability against electrolyte. Arising to the high light transparence of GaN and the favorable band alignment between GaN and InGaAsN, InGaAsN/GaN photoanode exhibited the enhanced light absorption and improved charge transfer and separation efficiency. As a result, the optimized InGaAsN/GaN photoanode showed a high photocurrent density of ∼120 mA cm−2 at 0.5 V vs. reversible hydrogen electrode (RHE) and an applied bias photo-to-current efficiency (ABPE) of over 6%. This study reveals that InGaAsN will be expected to be utilized in long-term and high-efficiency PEC cells.