title: Photoassisted enhancement of the electrocatalytic oxidation of formic acid on platinized TiO₂ nanotubes.
abstract: A solvothermal method is used to deposit Pt nanoparticles on anodized TiO2 nanotubes (T_NT). Surface characterization using SEM, EDX, and XRD indicates the formation of polycrystalline TiO2 nanotubes of 110 ± 10 nm diameter with Pt nanoparticle islands. The application of the T_NT/Pt photoanode has been examined toward simultaneous electrooxidation and photo(electro)oxidation of formic acid (HCOOH). Upon UV-vis photoillumination, the T_NT/Pt photoelectrode generates a current density of 72 mA/cm(2), which is significantly higher (∼39-fold) than that of the T_NT electrode (1.85 mA/cm(2)). This boosting in the overall current is attributable to the enhanced oxidation of formic acid at the T_NT/Pt-electrolyte interface. Further, a series of cyclic voltammetric (CV) responses, of which each anodic scan is switched to photoillumination at a certain applied bias (i.e., 0.2 V, 0.4 V, etc.), is used to identify the role of T_NT/Pt as a promoter for the photoelectrooxidation of formic acid and understand a carbon monoxide (CO)-free pathway. Chronoamperometric (j/t) measurements demonstrate the evidence of an external bias dependent variation in the time lag during the current stabilization. An analysis of the CV plots and j/t profiles suggests the existence of both the charge-transfer controlled process and the diffusion-controlled process during formic acid photoelectrooxidation.
authors.affiliation: Department of Chemical and Materials Engineering and ‡Department of Civil and Environmental Engineering, University of Nevada , Reno, Nevada 89557, United States.
authors.forename: Nazrul
authors.initials: N
authors.lastname: Mojumder
authors.forename: Swagotom
authors.initials: S
authors.lastname: Sarker
authors.forename: Syed Arslan
authors.initials: SA
authors.lastname: Abbas
authors.forename: Zong
authors.initials: Z
authors.lastname: Tian
authors.forename: Vaidyanathan Ravi
authors.initials: VR
authors.lastname: Subramanian