Direct Imaging of Highly Anisotropic Photogenerated Charge Separations on Different Facets of a Single BiVO₄ Photocatalyst

Abstract

Spatially resolved surface photovoltage spectroscopy (SRSPS) was employed to obtain direct evidence for highly anisotropic photogenerated charge separation on different facets of a single BiVO4 photocatalyst. Through the controlled synthesis of a single crystal with preferentially exposed {010} facets, highly anisotropic photogenerated hole transfer to the {011} facet of single BiVO4 crystals was observed. The surface photovoltage signal intensity on the {011} facet was 70 times stronger than that on the {010} facets. The influence of the built‐in electric field in the space charge region of different facets on the anisotropic photoinduced charge transfer in a single semiconductor crystal is revealed.

Heterogeneous photocatalysts: an overview of classic and modern approaches for optical, electronic, and charge dynamics evaluation

“…39 Coupling of spatially resolved surface photovoltage spectroscopy (SRSPS) with Kelvin probe force microscopy (KPFM) has been demonstrated to be useful in showing the highly anisotropic photoinduced charge separation on the different crystal facets of a single photocatalyst. 40 The combination of optical and electrochemical techniques such as spatially and temporally resolved single-particle spectroelectrochemistry is also helpful in revealing the carrier dynamics of a photocatalyst in relation to its crystal faces. 41 Another major downside of the techniques outlined in preceding sections is that the measurements are typically done before and after the photocatalytic or photoelectrochemical reaction.…”

Surface Strategies for Particulate Photocatalysts toward Artificial Photosynthesis

“…[171][172][173] Here, the precisely controlled synthesis, theoretical simulations, and advanced in situ time-and space-resolved characterization techniques are highly desirable to be combined to deepen our understanding of the surface catalytic reaction process. [174][175][176] Although the currently obtained STH values are typically around 1% in small-scale trials, which are lower than the benchmark STH value of 10%, it is time to put more effort into applied research, such as large scalable production of promising narrow bandgap photocatalysts consisting of inexpensive and earth-abundant elements, reactor design and manufacture, and the techno-economic analysis of the whole industrial process. 177 Artificial photosynthesis for solar fuel production has a bright future for simultaneously addressing the energy crisis and environmental challenges, so it is expected that multiple collaborations in this exciting research field will speed its industrial process.…”

Photocatalytic activity enhanced via surface hybridization

“…This in situ characterization provides the most direct physical image for the microscopic mechanism of the interface. [119][120][121] However, the report of KPFM technology measurement on the organic/inorganic surface hybrid interface is almost blank. The possible reason is that the powder-type surface hybrid photocatalyst is difficult to distinguish the interface under KPFM, and/or the neglect of the exploration of the interface electronic structure.…”

“…In addition, the measurement of the interface KPFM under light conditions can directly detect the influence of light on the electronic structure of the interface. This in situ characterization provides the most direct physical image for the microscopic mechanism of the interface 119‐121 . However, the report of KPFM technology measurement on the organic/inorganic surface hybrid interface is almost blank.…”