Issue 10, 2018

Photo-electrochemical hydrogen production from neutral phosphate buffer and seawater using micro-structured p-Si photo-electrodes functionalized by solution-based methods

Abstract

Solar fuels such as H2 generated from sunlight and seawater using earth-abundant materials are expected to be a crucial component of a next generation renewable energy mix. We herein report a systematic analysis of the photo-electrochemical performance of TiO2 coated, microstructured p-Si photo-electrodes (p-Si/TiO2) that were functionalized with CoOx and NiOx for H2 generation. These photocathodes were synthesized from commercial p-Si wafers employing wet chemical methods. In neutral phosphate buffer and standard 1 sun illumination, the p-Si/TiO2/NiOx photoelectrode showed a photocurrent density of −1.48 mA cm−2 at zero bias (0 VRHE), which was three times and 15 times better than the photocurrent densities of p-Si/TiO2/CoOx and p-Si/TiO2, respectively. No decline in activity was observed over a five hour test period, yielding a Faradaic efficiency of 96% for H2 production. Based on the electrochemical characterizations and the high energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) and emission spectroscopy measurements performed at the Ti Kα1 fluorescence line, the superior performance of the p-Si/TiO2/NiOx photoelectrode was attributed to improved charge transfer properties induced by the NiOx coating on the protective TiO2 layer, in combination with a higher catalytic activity of NiOx for H2-evolution. Moreover, we report here an excellent photo-electrochemical performance of p-Si/TiO2/NiOx photoelectrode in corrosive artificial seawater (pH 8.4) with an unprecedented photocurrent density of 10 mA cm−2 at an applied potential of −0.7 VRHE, and of 20 mA cm−2 at −0.9 VRHE. The applied bias photon-to-current conversion efficiency (ABPE) at −0.7 VRHE and 10 mA cm−2 was found to be 5.1%.

Graphical abstract: Photo-electrochemical hydrogen production from neutral phosphate buffer and seawater using micro-structured p-Si photo-electrodes functionalized by solution-based methods

Supplementary files

Article information

Article type
Paper
Submitted
21 jun 2018
Accepted
15 aug 2018
First published
16 aug 2018
This article is Open Access
Creative Commons BY-NC license

Sustainable Energy Fuels, 2018,2, 2215-2223

Photo-electrochemical hydrogen production from neutral phosphate buffer and seawater using micro-structured p-Si photo-electrodes functionalized by solution-based methods

A. Kawde, A. Annamalai, L. Amidani, M. Boniolo, W. L. Kwong, A. Sellstedt, P. Glatzel, T. Wågberg and J. Messinger, Sustainable Energy Fuels, 2018, 2, 2215 DOI: 10.1039/C8SE00291F

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