Facet-dependent spatial charge separation with rational cocatalyst deposition on BiVO₄

Rational assembly of cocatalyst on the photocatalyst with exposed functional crystal facets has been demonstrated to be viable in enhancing the photocatalytic activity. However, greater attention is paid to the property of the loaded cocatalyst while the effect of varied functional facet exposure is relatively less discussed. Herein, dual-faceted BiVO₄ with well-defined {010} and {110} facets but with varied {010}/{110} exposure extent ratios are coupled with CoO_x which is known as a cocatalyst for water oxidation. The enhancement induced by the cocatalyst loading depends on both its deposit location and the ratio of {010}/{110} facet exposure. When selectively deposited on oxidation {110} facet, CoO_x generates over two-fold enhancement on BiVO₄ in photocatalytic oxygen evolution as compared to its randomly deposited analogue. Meanwhile, the {010}-dominant BiVO₄ is more obviously benefited from the cocatalyst loading to both photocatalytic water oxidation and hydrogen peroxide generation reactions with respect to the {110}-dominant BiVO₄. Further investigation reveals that CoO_x functions more effectively in PL quenching and generating greater band bending on {010}-dominant BiVO₄, substantiating the better enhancement in reducing charge recombination and forming larger space charge region width for charge separation, which deliver greater photocatalytic activity enhancement on {010}-dominant BiVO₄.