Highly Enhanced Visible-Light-Driven Photoelectrochemical Performance of ZnO-Modified In2S3 Nanosheet Arrays by Atomic Layer Deposition

Ming Li,Jing Hu,Yafei Zhang,Yunhui Wang,Zhi Yang,Baofang Cai,Xinglong Tu,Jing Lu,Yanjie Su

doi:10.1007/s40820-018-0199-z

Ming Li, Jing Hu + Show 7 more

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https://doi.org/10.1007/s40820-018-0199-z

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Abstract

Photoanodes based on In2S3/ZnO heterojunction nanosheet arrays (NSAs) have been fabricated by atomic layer deposition of ZnO over In2S3 NSAs, which were in situ grown on fluorine-doped tin oxide glasses via a facile solvothermal process. The as-prepared photoanodes show dramatically enhanced performance for photoelectrochemical (PEC) water splitting, compared to single semiconductor counterparts. The optical and PEC properties of In2S3/ZnO NSAs have been optimized by modulating the thickness of the ZnO overlayer. After pairing with ZnO, the NSAs exhibit a broadened absorption range and an increased light absorptance over a wide wavelength region of 250–850 nm. The optimized sample of In2S3/ZnO-50 NSAs shows a photocurrent density of 1.642 mA cm−2 (1.5 V vs. RHE) and an incident photon-to-current efficiency of 27.64% at 380 nm (1.23 V vs. RHE), which are 70 and 116 times higher than those of the pristine In2S3 NSAs, respectively. A detailed energy band edge analysis reveals the type-II band alignment of the In2S3/ZnO heterojunction, which enables efficient separation and collection of photogenerated carriers, especially with the assistance of positive bias potential, and then results in the significantly increased PEC activity.

Highlights

Photoelectrochemical (PEC) water splitting is regarded as one of the most attractive approaches for producing hydrogen in a clean, renewable, and eco-friendly manner to store solar energy, which has aroused significant interest in the recent years [1,2,3,4,5]
To fabricate heterojunction nanosheet arrays (NSAs), the In2S3 nanosheets were conformably coated with ZnO overlayers through a thermal atomic layer deposition (ALD) process at 150 °C (Fig. 1a)
The results show that In2S3/ZnO-50 NSAs display the highest photocurrent density, which is significantly much higher than that of the pure In2S3

Summary

Introduction

Photoelectrochemical (PEC) water splitting is regarded as one of the most attractive approaches for producing hydrogen in a clean, renewable, and eco-friendly manner to store solar energy, which has aroused significant interest in the recent years [1,2,3,4,5]. There is no single one material that can satisfy all the aforementioned requirements among more than about 130 types of semiconductor materials [6] To address these challenges, nanostructured architectures have been explored because of their various advantages compared to bulk materials [8,9,10,11]. Among the known nanostructured semiconductors, metal chalcogenides have attracted substantial attention as a group of highly efficient photocatalysts for PEC water splitting [15]. The defect spinel structure b-In2S3, which is an n-type semiconductor with a bandgap of 2.0–2.3 eV, has been reported to be a promising photoanode material for PEC water splitting under visible-light irradiation in all three different crystal structures owing to its relatively negative conduction band edge, moderate charge transport properties, stable chemical, and physical characteristics along with low toxicity [20,21,22]. BIn2S3 nanocrystals with various 2D morphologies, such as nanosheets, nanoplates, nanoflakes, and nanobelts, have been successfully synthesized by different methods as photoanode materials for PEC applications [23,24,25,26]

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