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Vertically aligned 2.45 μm anatase nanowires were produced via a simple chemical bath deposition technique using a low-cost, easy to handle, water-soluble titanium salt precursor. The nanowires wer...

Photocatalytic water splitting in a novel, UV-irradiated fluidized bed reactor system with Pt-deposited titanium dioxide (TiO2) particles has been explored as an alternative approach to hydrogen production. A model describing the water splitting performance of the fluidized bed system was developed through a holistic approach combining fluidized bed theory, mass transfer effects, an optical model, and a proposed mechanism for the parasitic Pt-catalysed back reaction of H2 and O2. The model was validated experimentally using fluidizable Pt-deposited TiO2 particles. It was found that the efficiency of the fluidized bed water splitting system is dependent on the rate of mass transfer in the gas–liquid separator, while the overall rate of hydrogen evolution was found to vary with the height and density of the photocatalyst bed in the reactor; all of which are functions of the fluidization flow rate. It is shown that maximizing the rate of mass transfer in the gas–liquid separator can greatly diminish losses due to the Pt-catalysed back reaction of H2 and O2, yielding significant gains in efficiency and the overall rate of hydrogen production. The application of the model to the design of the fluidized bed water splitting system, the sub-systems and the photocatalyst particles is discussed.

UV-irradiated fluidized bed reactor system and Pt-loaded TiO2 spheres were developed for photocatalytic water splitting. This novel approach was explored as a means to minimize the parasitic back reaction, mass transport and radiation distribution effects that limit the performance and scalability of immobilized-film and suspended slurry photocatalysts typically employed for photocatalytic hydrogen production. By fluidizing Pt-loaded TiO2 spheres in a 2.2 M Na2CO3 solution, steady hydrogen production rates up to 211 μmol/h with an apparent quantum efficiency of 1.33% were achieved upon UV-irradiation. This demonstrates a marked 44% increase in the apparent quantum efficiency when compared to the performance of a traditional Pt-loaded TiO2 suspended slurry photocatalyst in the same reactor. It is hypothesized that this enhanced performance is primarily due to improved separation of the evolved H2 and O2 from the Pt-loaded photocatalyst particles, thus reducing the parasitic back reaction.

Since the discovery of photocatalytic watersplitting over titanium dioxide (TiO 2 ), researchers have typically only employed immobilized-film and suspended slurry photocatalysts. Here we present watersplitting in a UV- irradiated fluidized bed reactor with a novel, fluidizable watersplitting photocatalyst. This approach was taken to address the mass-transfer effects, poor radiation distribution, parasitic back-reaction and photocatalyst handling difficulties that limit the efficiency and scalability of existing watersplitting systems. Using a 2.2 M Na 2 CO 3 solution, significant hydrogen production rates were achieved. A marked increase in the hydrogen production rate was observed when compared to results obtained by a suspended slurry TiO 2 photocatalyst in the same reactor.