Shape anisotropic semiconductors are advanced catalysts for resolving energy crises. However, modification studies are still needed to overcome their intrinsic disadvantages, such as the lack of active sites. With this aim, an excellent hydrogen evolution photocatalyst Rh@Cr2O3-loaded PbMoO4 twenty-six facet polyhedron (PM/Rh@Cr2O3) has been synthesized by a liquid method. Based on XPS, electrochemical investigation and hydrogen evolution reaction (HER) test, it is demonstrated that Rh acts as an electron collector and active site; moreover, Cr2O3 can assist Rh in the dissociation of water. In addition, Cr2O3 can also inhibit the reverse reaction of water splitting as well as the mass transfer of water. In conclusion, the H2 yield rate increased from 0 μmol g−1 h−1 of PbMoO4 (PM) to 704 μmol g−1 h−1 of PM/Rh@Cr2O3, and PM/Rh@Cr2O3 exhibited excellent photo-stability.
Bi 3 TiNbO 9 , a layered ferroelectric photocatalyst, exhibits great potential for overall water splitting through efficient intralayer separation of photogenerated carriers motivated by a depolarization field along the in-plane a -axis. However, the poor interlayer transport of carriers along the out-of-plane c -axis, caused by the significant potential barrier between layers, leads to a high probability of carrier recombination and consequently results in low photocatalytic activity. Here, we have developed an efficient photocatalyst consisting of Bi 3 TiNbO 9 nanosheets with a gradient tungsten (W) doping along the c -axis. This results in the generation of an additional electric field along the c -axis and simultaneously enhances the magnitude of depolarization field within the layers along the a -axis due to strengthened structural distortion. The combination of the built-in field along the c -axis and polarization along the a -axis can effectively facilitate the anisotropic migration of photogenerated electrons and holes to the basal {001} surface and lateral {110} surface of the nanosheets, respectively, enabling desirable spatial separation of carriers. Hence, the W-doped Bi 3 TiNbO 9 ferroelectric photocatalyst with Rh/Cr 2 O 3 cocatalyst achieves an efficient and durable overall water splitting feature, thereby providing an effective pathway for designing excellent layered ferroelectric photocatalysts.
The synergistic coupling of light and heat in solar energy has attracted increasing research attention. In this work, both codoping and coloading were applied to SrTiO 3 -based catalysts to improve their solar photo and thermal conversion, respectively, and maximum productivities of 51.55 and 25.59 mmol·g −1 ·h −1 were achieved for H 2 and O 2 in photothermal synergistic water splitting. The yield of H 2 was nearly double that achieved via pure photocatalysis. In addition to many experiments and characterizations, DFT calculations were also performed to clarify the photothermal synergy. It was found that both the light absorbance and mobility of photoinduced carriers could be promoted by solar thermal effects in the material. Meanwhile, the energy barriers of the key steps were reduced with increasing temperature in the hydrogen production driven by solar photo effects. This work offers new ideas for designing catalysts for solar hydrogen production with photothermal synergistic strategies.
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