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Issue 5, 2019
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Creating stable interfaces between reactive materials: titanium nitride protects photoabsorber–catalyst interface in water-splitting photocathodes

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Abstract

The development of a solar-driven water splitting device that replaces costly precious metals, while achieving stable high performance, is a major challenge. Transition metal phosphides are active and low-cost catalysts for the hydrogen evolution reaction (HER), although, none thus far have exhibited stable performance when interfaced with semiconductors. Here, we report on a monolithic junction consisting of cubic-NiP2:TiN:Si, fabricated using both commercial and custom Si photovoltaics. Stable performance is achieved using an ultrathin film of crystalline TiN that effectively hinders atomic diffusion between interfaces during fabrication. Crystalline cubic-NiP2 deposited on TiN/n+p-Si retains 97% of the bare Si photovoltage, comparable saturation current density to bare Si, and has a turnover frequency of 1.04 H2 per site per s at −100 mV applied potential. In acid, it requires only −150 mV additional overpotential compared to the benchmark, Pt/TiN/n+p-Si, to reach a HER photocurrent density of −10 mA cm−2. This photocathode maintains a stable H2 photocurrent (±10%) for at least 125 hours, the duration of testing. When the same layers are fabricated on a commercial Si solar cell, this photocathode produced double the photocurrent density (36.3 mA cm−2, under simulated 1.5 AM G illumination). Physical characterization gives detailed information on the properties responsible for the observed activity and durability of these interfaces. In general, the thin-film methodology presented here is widely applicable, demonstrates superior activity, and achieves long-term stability.

Graphical abstract: Creating stable interfaces between reactive materials: titanium nitride protects photoabsorber–catalyst interface in water-splitting photocathodes

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Supplementary files

Article information


Submitted
17 Dec 2018
Accepted
08 Jan 2019
First published
09 Jan 2019

J. Mater. Chem. A, 2019,7, 2400-2411
Article type
Paper
Author version available

Creating stable interfaces between reactive materials: titanium nitride protects photoabsorber–catalyst interface in water-splitting photocathodes

S. Hwang, S. H. Porter, A. B. Laursen, H. Yang, M. Li, V. Manichev, K. U. D. Calvinho, V. Amarasinghe, M. Greenblatt, E. Garfunkel and G. C. Dismukes, J. Mater. Chem. A, 2019, 7, 2400
DOI: 10.1039/C8TA12186A

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