Photoelectrochemical performance of tubewall‐separated titanium dioxide nanotube array photoelectrode

Abstract

AbstractTitanium dioxide nanotube array (TiO2 NTA) grown on titanium substrate has been fabricated as active photoelectrode for organic compound degradation. TiO2 NTA shows the tubewall‐separated nanotube arrangement and anatase crystal structure. Transient photocurrent of 1.86 mA and open‐circuit photovoltage of 0.26 V are determined to keep stable level under ultraviolet (UV) light irradiation, indicating its high photoelectrochemical activity. The cathodic polarization process causes more feasible electron transfer than the equilibrium process and anodic polarization process, which is consistent with the declining current response at an increasing positive potential. The photocatalytic activity of TiO2 NTA is fully evaluated through UV light‐induced photocatalysis and photoelectrocatalysis degradation of organic dye X‐3B as a reactant pollutant. The pseudo‐first‐order reaction rate constant is enhanced from 0.00346 min−1 for photocatalysis to 0.00521 min−1 for photoelectrocatalysis using Langmuir–Hinshelwood kinetic model of heterogeneous catalysis. The tubewall‐separated nanotube structure could induce photoelectron directional transport and provide extra interspace for reactant organic molecule diffusion at accessible surface area. The positive potential applied on TiO2 NTA could further promote photoelectron–hole pair separation. Two strategies of photoelectron generation and photoelectron–hole separation are accordingly adopted to improve its electro‐assisted photocatalytic activity. Therefore, the tubewall‐separated TiO2 NTA could present the promising photoelectrocatalysis application.