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Operando deconvolution of photovoltaic and electrocatalytic performance in ALD TiO₂ protected water splitting photocathodes.

ABSTRACT: In this work, we demonstrate that buried junction photocathodes featuring an ALD TiO₂ protective overlayer can be readily characterized using a variation of the dual working electrode (DWE) technique, where the second working electrode (WE2) is spatially isolated from the hydrogen-evolving active area. The measurement of the surface potential during operation enables the operando deconvolution of the photovoltaic and electrocatalytic performance of these photocathodes, by reconstructing J-?V curves (reminiscent of photovoltaic J-V curves) from the 3-electrode water splitting data. Our method provides a clearer understanding of the photocathode degradation mechanism during stability tests, including loss of the catalyst from the surface, which is only possible in our isolated WE2 configuration. A pn⁺Si/TiO₂ photocathode was first investigated as a well behaved model system, and then the technique was applied to an emerging material system based on Cu₂O/Ga₂O₃, where we uncovered an intrinsic instability of the Cu₂O/Ga₂O₃ junction (loss of photovoltage) during long term stability measurements.

SUBMITTER: Cui W

PROVIDER: S-EPMC6052736 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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