Photoelectrochemical Performance of BiVO_4 Photoanodes Integrated with [NiFe]-Layered Double Hydroxide Nanocatalysts

Abstract

We immobilized laser-made nickel iron layered double hydroxide ([NiFe]-LDH) nanocatalysts on BiVO_4 photoanodes. We compared photoelectrochemical performance of integrated [NiFe]-LDH–BiVO_4 photoanodes in sulfite-free aqueous electrolyte with photocurrent generation of neat BiVO_4 photoanodes in aqueous electrolyte with sulfite added as sacrificial hole acceptor. We optimized catalyst mass loading, which is a tradeoff between most efficient depletion of photogenerated holes that drive catalytic turnover and parasitic light absorption by the catalyst particles. We also mitigated nanocatalyst aggregation on the BiVO_4 surface by a surfactant that selectively ligated the catalysts or by dispersing the catalyst suspension more rapidly on the photoanode surface. Our rational optimization strategies enhanced photoelectrochemical performance of integrated nanocatalyst photoanodes: Two thirds of all photogenerated holes escaped loss processes in our optimized integrated [NiFe]-LDH–BiVO_4 photoanodes under 100 mW cm^(–2) of simulated air mass 1.5 G illumination in aqueous pH 9.2 buffered electrolyte. Our systematic optimization strategies for integration of highly efficient water oxidation nanocatalysts with a visible-light absorber provide a path towards functional artificial photosynthesis devices.

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