Photo-electrochemical hydrogen production from neutral phosphate buffer and seawater using micro-structured p-Si photo-electrodes functionalized by solution-based methods. Issue 10 (22nd August 2018)

• Record Type: Journal Article
• Authors: Kawde, Anurag; Annamalai, Alagappan; Amidani, Lucia; Boniolo, Manuel; Kwong, Wai Ling; Sellstedt, Anita; Glatzel, Pieter; Wågberg, Thomas; Messinger, Johannes
• Is Part Of: Sustainable energy & fuels. Volume 2:Issue 10(2018)
• Page Start: 2215
• Page End: 2223
• Publication Date: 2018-08-22
• Subjects: Renewable energy sources -- Periodicals; Fuel cells -- Periodicals; Electric batteries -- Periodicals; Electrochemistry -- Periodicals; 660.297
• DOI: 10.1039/c8se00291f
• Languages: English
• ISSNs: 2398-4902

Abstract

Abstract : Micro-structured p-Si/TiO2 /NiO x allows for efficient photoelectrochemical H2 production from seawater. 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 CoO x and NiO x 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 /NiO x 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 /CoO x 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 /NiO x photoelectrode was attributed to improved charge transfer properties induced by the NiO x coating on the protective TiO2 layer, in combination with a higher catalytic activity of NiO x for H2 -evolution. Moreover, we report here an excellent photo-electrochemical performance of p-Si/TiO2 /NiO x 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%.