Crystal Facet-Dependent Intrinsic Charge Separation on Well-Defined Bi4TaO8Cl Nanoplate for Efficient Photocatalytic Water Oxidation

The development of photocatalysts with wide spectral absorption and high charge separation efficiency has always been a pursued objective for photocatalytic solar energy conversion. Herein, we reported a wide-range visible-light-active Bi4TaO8Cl (BTOC) single crystal nanoplate with dominating {110} and {001} facets for enhancing the intrinsic charge separation efficiency. Insitu selective photodeposition of metals and metal oxides provides evidences of photogenerated electrons and holes spatially separated on {110} and {001} coexposed facets of BTOC, respectively. The intrinsic charge separation efficiency was demonstrated to be closely dependent on the crystal facets, which can be modulated by tuning the coexposed crystal facet ratio. Further surface modification of BTOC with suitable dual cocatalyst Ag and RuOx enables remarkable improvement of charge separation efficiency and photocatalytic water oxidation performance. Investigation by comparison between well-defined BTOC nanoplate and BTOC nanoparticles confirmed the significance of coexposed crystal facets for efficient spatial charge separation and the blocking of reverse reaction from Fe2+ to Fe3+ ions during water oxidation reaction, indicating that rational modulation of exposed crystal facets is significant for controlling the intrinsic charge separation efficiency on Bi4TaO8Cl photocatalyst for efficient photocatalytic water splitting.