Crystal Facet Dependence of Water Oxidation on BiVO₄Sheets under Visible Light Irradiation

Abstract

Monoclinic BiVO(4) crystals with preferentially exposed (040) facets were hydrothermally synthesized by using a trace amount of TiCl(3) as the directing agent; this function was confirmed by X-ray diffraction patterns (XRD) and high-resolution transmission electron microscopy (HRTEM). The effects of the directing agent TiCl(3) and the pH values applied during synthesis have been studied, and the optimized BiVO(4) sample with highly exposed (040) facet could be obtained by using 1.2 at.% of TiCl(3) as the directing agent at a pH value of 2. Some complementary techniques were also applied to exclude the effects of the structural and physical property changes, such as surface area and hydrophilicity. The photocatalytic activity of oxygen evolution on BiVO(4) is found to be proportionally correlated with the exposed surfaces of the (040) facet. It is assumed that the active sites with a BiV(4) structure on the exposed (040) facet is assigned to be responsible for the high activity of O(2) evolution.

Spatial separation of photogenerated electrons and holes among {010} and {110} crystal facets of BiVO4

“…A large single crystal of monoclinic BiVO 4 was prepared by the hydrothermal method 46,47 , and characterised by XRD patterns, UV-vis spectra and SEM images. The as-prepared BiVO 4 powder shows a smooth surface, regular decahedron shape, good crystallinity and characteristic visible-light absorption ( Supplementary Fig.…”

Polyhedral 30‐Faceted BiVO4 Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity

“…[21][22][23] The photocatalytic behavior of BiVO 4 is highly dependent on its surface structure, in which photogenerated electrons and holes can be preferentially separated and accumulated on {010} and {110} facets, respectively, via the driving force created by the different band energies of the two facets. [24,25] Herein, we report the synthesis unprecedented 30-faceted BiVO 4 polyhedra predominantly surrounded by high-index {132}, {321}, and {121} facets. These BiVO 4 materials exhibit 3-5 time enhancements in O 2 evolution from photocatalytic water oxidation, relatively to that of low-indexed counterparts.…”

Insights from Crystal Size and Band Gap on the Catalytic Activity of Monoclinic BiVO4

“…In order to realize this, the first challenge to be addressed is the accomplishment of the water oxidation half-reaction (2H 2 O O 2 + 4H + + 4e -), considered as a limiting step since it involves a thermodynamically uphill reaction comprising the simultaneous transference of 4 electrons [2], [8]. Furthermore, development of a catalyst which can utilize whole electromagnetic spectrum is preferred in order to enhance overall water splitting efficiency of photocatalysts [9].…”

“…Several synthesis methods have been utilized in order to prepare BiVO 4 powders of high quality, predominantly solid-state, aqueous-based and hydrothermal methods [8], [12], [16]- [18]; among them, a simple solution-based preparation method under acidic conditions has been chosen and applied here, involving the calcination of obtained BiVO 4 precipitates at different temperatures. From this, an in-depth analysis of some of the important physical parameters of as-obtained products allows for a coherent correlation with the different photocatalytic O 2 evolution.…”