Abstract
In order to enhance photocatalytic water splitting rates with Pt/TiO2 powder, sufficient agitation of the biphasic medium is required to switch surficial reactions to volumetric reactions. Additionally, agitation is conducive to higher diffusion rates of the generated hydrogen and co-produced oxygen, hindering their ability to re-couple to water on Pt loaded to TiO2 powder. In order to create agitation without consuming any electricity, a novel technique utilizing Rayleigh convection was applied, and its ability to enhance photocatalytic water splitting rates was evaluated. Higher Rayleigh convective flow rates resulted in higher photocatalytic water splitting rates. Utilization of Rayleigh convection approximately doubled the photocatalytic water splitting rates, despite relatively low convective flow velocities (obtained through simple thermo-hydrodynamic simulations). The rate enhancement achieved through Rayleigh convection is a result of its ability to disperse the ultrafine Pt/TiO2 particles throughout the whole medium, leading to volumetric reactions.
Highlights
Photocatalysts play important roles in a variety of applications, namely in water decontaminations, air pollutants degradations and water splitting [1]-[9]
Deeper solutions show slower H2 producing rates and longer dead times before any H2 production. These results could be attributed to the undesirable phenomena described in the introduction
Rather low Rayleigh convective flow rates are due to such low heating temperatures, a little more than doubled the photocatalytic water splitting rates as shown in Figure 4 might result from dispersing ultrafine Pt/TiO2 powder, that is to say, volumetric reactions
Summary
Photocatalysts play important roles in a variety of applications, namely in water decontaminations, air pollutants degradations and water splitting [1]-[9]. Water electrolysis is quite efficient (above 90 % in a converting efficiency), and it played important roles in the WE-NET [10] (World Energy Network) project using electric power generated from renewable energy sources such as hydropower and wind power, especially in Canada and northern Europe, respectively. Because of such a high efficiency of water electrolysis, agitation of the mixture of Pt/TiO2 and OSA solution must be realized without consuming any electricity. Promising future strategies for higher agitating intensities under lower temperatures, which might result to further enhancement of photocatalytic water splitting rates, are discussed
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