Macroporous V2O5−BiVO4 composites with a heterojunction structure have been successfully synthesized under the assistance of colloidal carbon spheres. X-ray diffraction, Raman, and X-ray photoelectron spectroscopies reveal that the as-prepared composites are composed of monoclinic BiVO4 and orthorhombic V2O5. The behavior of photogenerated charges in V2O5, BiVO4, and the V2O5−BiVO4 composite have been investigated through surface photovoltage spectroscopy (SPS) and transient photovoltage (TPV) techniques. It is demonstrated that the formation of heterojunction structure in the V2O5−BiVO4 composite plays an important role in the kinetic behaviors (including separation, transport, and recombination) of photogenerated charges. The heterojunction greatly increases the separation extent and the lifetime of the photogenerated charges in the composites.

Exploiting useful contacts: The exceptional catalytic performance of a photocatalyst composed of Pd nanoparticles and mesoporous carbon nitride for the dehydrogenation of formic acid in water at room temperature to produce H2 gas (see picture) is due to enhanced electron enrichment of the Pd nanoparticles through charge transfer at the interface of the Mott–Schottky contact.

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ZnO nanowire (NWs) arrays coated with CdS quantum dots (QDs) were successfully fabricated with a chemical bath deposition process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD) have been utilized to characterize the samples. We have studied the processes of separation and recombination of the photo-generated charges in the visible region by surface photovoltage (SPV) and transient photovoltage (TPV) measurements. By controlling the amount of attached CdS QDs we found that the surface photovoltage characteristics change significantly. With a liquid electrolyte as the hole transport medium, the quantum dot sensitized nanowire solar cells (QDSSCs) exhibited short-circuit currents ranging from 0.8 to 2.6 mA cm(-2) and open-circuit voltages of 0.35-0.44 V when illuminated with light intensity 100 mW cm(-2). The relation between the performance of QDSSCs and their photovoltage characterization was also discussed.

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