Abstract
Semiconductor nanowires with both nano- and micrometre dimensions have been used as effective materials for artificial photosynthesis; however, a single synthesis approach to provide rational control over the macroscopic morphology, which can allow for the high-throughput screening of photocatalytic performance, and carrier transfer between oxide and sulphide nanostructures has been poorly known. Our recent findings indicate that a single parameter, Nb foil thickness, in a vapor-phase synthesis method can alter the macroscopic morphology of resulting Nb2O5 nanowires. Thick Nb foil results in a free-standing Nb2O5 film, whereas a thinner foil leads to fragmentation to give a powder. During the synthesis process, a Rh dopant was provided through metal-organic chemical vapor deposition to reduce the Nb2O5 energy gap. Upon irradiation with visible light (λ > 440 nm), the free-standing nanowire film [Nb2O5:Rh-NW(F)] showed photoanodic current with a Faradaic efficiency of 99% for O2 evolution. Under identical irradiation conditions, the powdered counterpart [Nb2O5:Rh-NW(P)] showed activity for O2 evolution in the presence of an electron acceptor. The poor water-reduction ability was greatly enhanced by the Au-catalysed vapor-liquid-solid (VLS) growth of H2-evolving CdS onto the reduction sites of Nb2O5:Rh-NW(P) [Au/CdS/Nb2O5:Rh-NW(P)].
Highlights
Artificial photosynthesis harnessing sunlight to construct chemical bonds for use as a fuel is a key technologies to move towards a sustainable society[1,2,3]
An H2-evolving sulphide should be placed on the reduction site of the oxide because this positional relationship allows for efficient carrier transfer, and excessive sulphide utilization or deposition on the oxide could provoke a light-shielding effect
Self-catalytic growth and MOCVD were combined in a single synthesis approach to form Nb2O5:Rh-NW with two different macroscopic morphologies
Summary
Artificial photosynthesis harnessing sunlight to construct chemical bonds for use as a fuel is a key technologies to move towards a sustainable society[1,2,3]. The physical rotation[34], used in the VLS growth of CdS on the reduction site of the nanowire powder, was found to have an obvious effect on the H2 evolution activity (Fig. 1).
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