Sub-50 nm perovskite-type tantalum-based oxynitride single crystals with enhanced photoactivity for water splitting.

Xiao, Jiadong; Nakabayashi, Mamiko; Hisatomi, Takashi; Vequizo, Junie Jhon M; Li, Wenpeng; Chen, Kaihong; Tao, Xiaoping; Yamakata, Akira et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

A long-standing trade-off exists between improving crystallinity and minimizing particle size in the synthesis of perovskite-type transition-metal oxynitride photocatalysts via the thermal nitridation of commonly used metal oxide and carbonate precursors. Here, we overcome this limitation to fabricate ATaO<sub>2</sub>N (A = Sr, Ca, Ba) single nanocrystals with particle sizes of several tens of nanometers, excellent crystallinity and tunable long-wavelength response via thermal nitridation of mixtures of tantalum disulfide, metal hydroxides (A(OH)<sub>2</sub>), and molten-salt fluxes (e.g., SrCl<sub>2</sub>) as precursors. The SrTaO<sub>2</sub>N nanocrystals modified with a tailored Ir-Pt alloy@Cr<sub>2</sub>O<sub>3</sub> cocatalyst evolved H<sub>2</sub> around two orders of magnitude more efficiently than the previously reported SrTaO<sub>2</sub>N photocatalysts, with a record solar-to-hydrogen energy conversion efficiency of 0.15% for SrTaO<sub>2</sub>N in Z-scheme water splitting. Our findings enable the synthesis of perovskite-type transition-metal oxynitride nanocrystals by thermal nitridation and pave the way for manufacturing advanced long-wavelength-responsive particulate photocatalysts for efficient solar energy conversion.