InGaN-based photoanode with ZnO nanowires for water splitting.

Sungjin Moon,Heon Lee,Junjie Kang,Hongjian Li,Yangdoo Kim,Panpan Li,Vinhquang Dang,Hakjong Choi,Chaehyun Kim,Zhiqiang Liu

doi:10.1186/s40580-016-0092-8

Sungjin Moon, Heon Lee

Open Access

https://doi.org/10.1186/s40580-016-0092-8

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Abstract

The water splitting properties of InGaN photoanodes equipped with ZnO nanowires were examined in this study. Over the solar spectrum range, the absorbance exhibited a remarkable increase due to the enhanced light absorption caused by the ZnO nanowires. By varying the ZnO nanowires length, the photo-to-current density of photoanodes was increased from 0.017 to 0.205 mA/cm2 at 1.23 V versus reversible hydrogen electrode. Consequently, the incident-photon-to-current efficiency was increased by a factor of 5.5 as the ZnO nanowires growth time increased from 2 to 4 h. The results of this research demonstrate the importance of light absorbance and the surface reaction sites of photoanodes on energy harvesting.

Highlights

Materials such as Fe2O3, TiO2, Zinc oxide (ZnO), and InGaN have attracted significant attention in photoelectrochemical applications and solar energy storage because of their suitable band gaps for light absorption [1–4]
3 Results and discussion Scanning electron microscope (SEM) was used to investigate the morphology of the ZnO nanowires
The ZnO nanowire density can be tuned by changing the seed layer density and deposition time

Summary

Introduction

Materials such as Fe2O3, TiO2, ZnO, and InGaN have attracted significant attention in photoelectrochemical applications and solar energy storage because of their suitable band gaps for light absorption [1–4]. Pu et al have shown that Rh/Cr2O3 nanoparticles equipped InGaN/ GaN nanowires with additional charge decay pathways can increase overall water splitting efficiency [13]. This efficiency is not comparable to that of materials such as SnO2 and TiO2, because of the relatively low light absorption ratio of GaN materials [2, 14]. Kang et al Nano Convergence (2016) 3:34 hole-electron recombination [16] and construction of one-dimensional (1-D) nanostructured ZnO-based electrodes with various morphologies for increased surface area and improved charge transportation and light trapping [17–19]. To increase the efficiency of InGaN-based thin film photoanodes, ZnO nanowires have been adapted to InGaN materials grown by the MOCVD method. The correlation between the efficiency of photoanodes and the ZnO nanowire growth time was studied by measuring the light absorption spectrum, the photocurrent density-versus-voltage (J–V) properties, and the incident-photon-to-current efficiency (IPCE)

Experiment

Characterization of InGaN‐based material and ZnO nanowires

Results and discussion

Conclusions