Issue 12, 2012

Cu2O|NiOx nanocomposite as an inexpensive photocathode in photoelectrochemical water splitting

Abstract

A photoelectrochemical (PEC) cell for overall water splitting made of a Cu2O nanowire photocathode modified with a thin film of NiOx coupled to a WO3 nanosheet photoanode is presented. The photocathode was prepared by thermal annealing of Cu(OH)2 nanowires on a Cu foil under N2, followed by the deposition of a 10 nm NiOx film on the Cu2O nanowires (aspect ratio > 40). XPS spectra revealed that the surface species of NiOx is a mixture of NiO and Ni(OH)2, which enhances charge separation in photoexcited Cu2O, as confirmed by electrochemical impedance spectroscopy. The optimized NiOx modified Cu2O electrode shows a photocurrent density up to −4.98 mA cm−2 at −0.33 V and −0.56 mA cm−2 at 0.1 V vs. the normal hydrogen electrode (NHE) under white-light irradiation (26 mW cm−2) in an aqueous electrolyte solution at pH 6 and 25 °C. The formation of H2 gas was only observed by gas chromatography for NiOx-modified Cu2O and was not detectable for unmodified Cu2O electrodes during prolonged irradiation. The nanocomposite structure also resulted in a three-fold increase in photostability of Cu2O; 72 ± 3% of the initial photocurrent density remained for the NiOx modified Cu2O electrode after 20 min irradiation at 0.1 V vs. NHE. The optimized photocathode was subsequently used in a two-electrode PEC cell with an n-type WO3 nanosheet photoanode for overall water splitting. The different band gap of Cu2O (2 eV) and WO3 (2.6 eV) permits for efficient and complementary light absorption and sunlight-driven water splitting. The p/n heterojunction PEC cell operates with a small output of electricity even in the absence of an external bias. We demonstrate that a Cu2O-based electrode for H2 evolution can be prepared free of noble metals and we show its utilization in a PEC water splitting cell made solely from earth abundant elements.

Graphical abstract: Cu2O|NiOx nanocomposite as an inexpensive photocathode in photoelectrochemical water splitting

Supplementary files

Article information

Article type
Edge Article
Submitted
03 Jul 2012
Accepted
25 Aug 2012
First published
28 Aug 2012

Chem. Sci., 2012,3, 3482-3487

Cu2O|NiOx nanocomposite as an inexpensive photocathode in photoelectrochemical water splitting

C. Lin, Y. Lai, D. Mersch and E. Reisner, Chem. Sci., 2012, 3, 3482 DOI: 10.1039/C2SC20874A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements