Abstract : A push-pull organic dye and a cobaloxime catalyst were successfully co-grafted on NiO and CuGaO$_2$ to form efficient molecular photocathodes for H$_2$ production with >80% Faradaic efficiency. CuGaO$_2$ is emerging as a more effective p-type semiconductor in photoelectrochemical cells and yields a photocathode with four-fold higher photocurrent densities and 400 mV more positive onset photocurrent potential compared to the one based on NiO. Such an optimized CuGaO$_2$ photocathode was combined with a TaONǀCoO$_x$ photoanode in a photoelectrochemical cell. Operated in this Z-scheme configuration, the two photoelectrodes produced H$_2$ and O$_2$ from water with 87% and 88% Faradaic efficiency, respectively, at pH 7 under visible light and in the absence of an applied bias, equating to a solar to hydrogen conversion efficiency of 5.4×10$^{−3}$%. This is, to the best of our knowledge, the highest efficiency reported so far for a molecular-based noble metal-free water splitting Z-scheme.
https://hal-cea.archives-ouvertes.fr/cea-02147070
Contributor : Serge Palacin
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Submitted on : Tuesday, June 4, 2019 - 1:59:20 PM
Last modification on : Monday, June 24, 2019 - 10:57:52 AM
Christopher Windle, Hiromu Kumagai, Masanobu Higashi, Romain Brisse, Sébastien Bold, et al.. Earth-Abundant Molecular Z-Scheme Photoelectrochemical Cell for Overall Water-Splitting. Journal of the American Chemical Society, American Chemical Society, In press, 141, pp.9593-9602. ⟨https://doi.org/10.1021/jacs.9b02521⟩. ⟨10.1021/jacs.9b02521⟩. ⟨cea-02147070⟩
