Micropillar arrays supported mesoporous TiO2 photoanode for enhancing photoelectrochemical performance

Mesoporous TiO 2 photoanode shows promising application in photoelectrochemical systems due to large specific surface area and regular mesoporous structure. The evaporation-induced self-assembly method is usually employed for the preparation of mesoporous TiO 2 photoanodes. However, the photoelectrochemical performance of such a mesoporous TiO 2 photoanode prepared by this method is still unable to meet the demand owing to low photocatalyst loading, because the in-plane tensile stress during calcination may destroy the mesoporous TiO 2 film. To address this issue, the micropillar arrays supported mesoporous TiO 2 photoanode is proposed by directly synthesizing mesoporous TiO 2 film on the micropillar arrays loaded substrate. It is shown that the micropillar arrays interspersed inside the mesoporous TiO 2 film can help release the in-plane tensile stress during calcination, keeping the mesoporous structure intact. As a result, the photoelectrochemical cell with the optimized micropillar arrays supported mesoporous TiO 2 photoanode exhibits superior performance than does the nanoparticles-packed TiO 2 photoanode. Remarkably, the proposed method allows for preparing the TiO 2 micropillar arrays, by which the formed TiO 2 micropillar arrays supported mesoporous TiO 2 photoanode yields the optimal performance. As compared to the nanoparticles-packed TiO 2 photoanode, the short circuit current density and maximum power density increase by 63.6 % and 18.8 %, respectively.