文摘
We present herein an example of nanocrystalline antimony-doped tin oxide (nc-ATO) disordered macroporous 鈥渋nverse opal鈥?3D electrodes as efficient charge-collecting support structures for the electrolysis of water using a hematite surface catalyst. The 3D macroporous structures were created via templating of polystyrene spheres, followed by infiltration of the desired precursor solution and annealing at high temperature. Using cyclic voltammetry and electrochemical impedance spectroscopy, it was determined that the use of this 3D transparent conducting oxide with a hematite surface catalyst allowed for a 7-fold increase in active surface area for water splitting with respect to its 2D planar counterpart. This ratio of surface areas was evaluated based on the presence of oxidized trap states on the hematite surface, as determined from the equivalent circuit analysis of the Nyquist plots. Furthermore, the presence of nc-ATO 2D and 3D 鈥渦nderlayer鈥?structures with hematite deposited on top resulted in decreased charge transfer resistances and an increase in the number of available active surface sites at the semiconductor鈥搇iquid junction when compared to hematite films lacking any nc-ATO substructures. Finally, absorption, transmission, and reflectance spectra of all of the tested films were measured, suggesting the feasibility of using 3D disordered structures in photoelectrochemical reactions, due to the high absorption of photons by the surface catalyst material and trapping of light within the structure.
Keywords:
water splitting; hematite; macroporous electrode; inverse opal; transparent conducting oxide; impedance spectroscopy; cyclic voltammetry
