Constructing photocatalytically favorable surface structure in synthesizing photocatalysts plays an important role in enhancing the photocatalytic activity of semiconductor photocatalysts. In this report, oxygen-deficient anatase TiO2 sheets with dominant {001} facets were synthesized via a facile one-pot hydrothermal route with solid metallic titanium diboride as precursor. In contrast to anatase TiO2 sheets with dominant {001} facets free of oxygen deficiency and surface fluorine, anatase TiO2 sheets with oxygen deficiency and surface fluorine are subject to obvious surface reconstruction as evidenced by two new Raman-active modes at 155 and 171 cm−1 and the weakened B1g mode at 397 cm−1. Further analysis based on X-ray photoelectron spectroscopy (XPS) spectra of Pt 4f and F 1s provided a clear evidence for the greatly strengthened interaction between Pt-loaded and TiO2 matrix as a result of a special electron-transfer process on the reconstructed surface structure of TiO2 with both oxygen deficiency and fluorine. Importantly, the reconstructed surface structure as well as the strengthened interaction between Pt-loaded and TiO2 matrix can substantially enhance the hydrogen evolution rate from photocatalytic water splitting reactions.

The surface structures of doped semiconductor photocatalysts play a vital role in determining visible light absorbance, transfer and redox potentials of charge carriers, as well as the inhibition of recombination. We examine the photocatalysis of anatase TiO2 with surface terminating Ti−O−B−N structures from both experimental and computational perspectives. This codoped titania system shows much better photocatalytic activity in generating •OH radical species and degrading organic pollutants in comparison with B-doped anatase titania. We present indicative evidence that the Ti−O−B−N surface structures can exhibit bifunctionality in promoting photocatalysis, (i) supplying partially occupied localized states attributed to B−N coupling with spectral distribution that is advantageous for enhancing visible light absorption and (ii) acting as photocatalytic “hot sites” to support localization and separation of charge carriers at the surface. These results offer important implications for designing highly efficient photocatalysts based on codoping strategies.

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In this letter, we quantitatively investigated epitaxial GaAs nanowires catalyzed by thin Au films of different thicknesses on GaAs (111)B substrates in a metal-organic chemical vapor deposition reactor. Prior to nanowire growth, the de-wetting of Au thin films to form Au nanoparticles on GaAs (111)B in AsH3 ambient at different temperatures is investigated. It is found that with increasing film thickness, the size of the Au nanoparticles increases while the density of the nanoparticles reduces. Furthermore, higher annealing temperature produces larger Au nanoparticles for a fixed film thickness. As expected, the diameters and densities of the as-grown GaAs nanowires catalyzed by these thin Au films reflect these trends.