Solar water splitting with nanostructured hematite: The role of annealing-temperature

Abstract The vertically aligned hematite (Fe 2 O 3 ) nanorods fabrication has been considered as an effective method for photoelectrochemical (PEC) water splitting. To improve the activity, two-step annealing treatment in the temperature range from 550 °C to 800 °C was proposed for the Fe 2 O 3 nanorods synthesized by hydrothermal method. This study reveals that the OER (oxygen evolution reaction) performance increases with the annealing temperature, which yields photocurrent density of 1.036 mA cm −2 and ABPC (applied bias photon-to-current) efficiency of 0.86% under simulated solar illumination of 100 mW cm −2 (AM 1.5G) condition at 1.23 V vs. RHE (reversible hydrogen electrode) at 800 °C. The second-step short time high temperature annealing treatment has a primary contribution on the fine-tune crystallite size and the diffusion and incorporation of Sn atoms. In addition, examining the corresponding resistance properties reveal a substantial improvement in the conductivity within the hematite film and at the conducting interface, and a suppressed charge carrier recombination process.