A nanostructured NiO/cubic SiC p-n heterojunction photoanode for enhanced solar water splittingElectronic supplementary information (ESI) available. See DOI: 10.1039/c9ta00020h

• Main Authors: Jian, Jingxin, Shi, Yuchen, Ekeroth, Sebastian, Keraudy, Julien, Syväjärvi, Mikael, Yakimova, Rositsa, Helmersson, Ulf, Sun, Jianwu
• Format: Journal Article
• Language: English
• Published: 26.02.2019
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta00020h

Photoelectrochemical (PEC) water-splitting offers a promising method to convert the intermittent solar energy into renewable and storable chemical energy. However, the most studied semiconductors generally exhibit a poor PEC performance including low photocurrent, small photovoltage, and/or large onset potential. In this work, we demonstrate a significant enhancement of photovoltage and photocurrent together with a substantial decrease of onset potential by introducing electrocatalytic and p-type NiO nanoclusters on an n-type cubic silicon carbide (3C-SiC) photoanode. Under AM1.5G 100 mW cm −2 illumination, the NiO-coated 3C-SiC photoanode exhibits a photocurrent density of 1.01 mA cm −2 at 0.55 V versus reversible hydrogen electrode ( V RHE ), a very low onset potential of 0.20 V RHE and a high fill factor of 57% for PEC water splitting. Moreover, the 3C-SiC/NiO photoanode shows a high photovoltage of 1.0 V, which is the highest value among reported photovoltages. The faradaic efficiency measurements demonstrate that NiO also protects the 3C-SiC surface against photo-corrosion. The impedance measurements evidence that the 3C-SiC/NiO photoanode facilitates the charge transfer for water oxidation. The valence-band position measurements confirm the formation of the 3C-SiC/NiO p-n heterojunction, which promotes the separation of the photogenerated carriers and reduces carrier recombination, thus resulting in enhanced solar water-splitting. A 3C-SiC/NiO p-n heterojunction photoanode exhibits a substantially improved photoelectrochemical water-splitting performance in terms of photocurrent, onset potential and fill-factor.