Tuning orientation of doped hematite photoanodes for enhanced photoelectrochemical water oxidation

The limited conductivity in hematite has been currently considered as a critical bottleneck in improving the efficiency of solar-driven water oxidation. Here we shed light on the improvement of carrier conductivity by combing orientation control and transition metal doping. To rule out the influence of surface facets of hematite when adjusting the film orientation, the hematite photoanode films were fabricated by assembling the spherical particles with single crystalline nature. The doped hematite particles were aligned with (001) plane normal to the substrate by a magnetic field (MF) during the drop-casting process. A considerable improvement in photocurrent density was resulted from the orientation control, which is due to the increased carrier density from Sn doping and efficient charge transportation in the (001) plane observed through electrochemical impedance spectra.