Photo-assisted Enhancement of Formic Acid Oxidation over Platinized TiO2 Nanotube Composite
AuthorMojumder, Nazrul Islam
AdvisorSubramanian, Vaidyanathan (Ravi)
Chemical and Materials Engineering
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1D TiO<sub>2</sub> nanotubes (TNT) prepared by anodization deposited with 0D Pt nanoparticles (TNT&ndashPt) prepared by a solvothermal method is used as a photoelectrocatalyst for formic acid (FA) oxidation. SEM, XRD, absorbance, EDX analysis indicates the polycrystalline TiO<sub>2</sub> nanotubes of approximately 100±10 nm in diameter with 5&ndash25 nm dimensions of Pt aggregates are formed. The composite was tested as a working electrode in the photoelectrooxidation of FA for applications such as fuel cells. Electrochemical characterization of the synthesized electrode was studied under the effect of light in order to determine the current generation of the photoactive electrode. The results show that Pt coupled with TiO<sub>2</sub> leads to a synergistic, i.e. boosting effect, in the increase of current density. In the presence of light, there is about a 5&ndashfold increase in current density (75.1 mA/cm<super>2</super>) as compared to the absence of light (16.0 mA/cm<super>2</super>). At a bias of 0.45 V the increase is about 20&ndashfold in the presence of light (62.5 mA/cm<super>2</super>) compared to (3.04 mA/cm<super>2</super>) in the absence of light. In addition, the effect of light in the current generation as a result of voltage bias effect is shown, thus leading to the observation that the longer the working electrode encounters light, the greater number of electrons that are generated to yield a higher current density. The study of this effect indicates a progressive current generation from light off to light on, traversing the whole range of the current generation. Thus, a combination of Helmholtz electrical double layer based limitation and mass transport limitations determine the extent of this boosting phenomenon.