Micropillar arrays supported mesoporous TiO₂ photoanode for enhancing photoelectrochemical performance

Mesoporous TiO₂ 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 TiO₂ photoanodes. However, the photoelectrochemical performance of such a mesoporous TiO₂ 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 TiO₂ film. To address this issue, the micropillar arrays supported mesoporous TiO₂ photoanode is proposed by directly synthesizing mesoporous TiO₂ film on the micropillar arrays loaded substrate. It is shown that the micropillar arrays interspersed inside the mesoporous TiO₂ 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 TiO₂ photoanode exhibits superior performance than does the nanoparticles-packed TiO₂ photoanode. Remarkably, the proposed method allows for preparing the TiO₂ micropillar arrays, by which the formed TiO₂ micropillar arrays supported mesoporous TiO₂ photoanode yields the optimal performance. As compared to the nanoparticles-packed TiO₂ photoanode, the short circuit current density and maximum power density increase by 63.6 % and 18.8 %, respectively.