Enhancing Hematite Photoanode Activity for Water Oxidation by Incorporation of Reduced Graphene Oxide

Two effective methods to prepare reduced graphene oxide (rGO)/hematite nanostructured photoanodes and their photoelectrochemical characterization towards water splitting reactions are presented. First, graphene oxide (GO) is reduced to rGO using hydrazine in a basic solution containing tetrabutylammonium hydroxide (TBAOH), and then deposited over the nanostructured hematite photoanodes previously treated at 750 °C for 30 min. The second method follows the deposition of a paste containing a mixture of hematite nanoparticles and rGO sheets by the doctor-blade method, varying the rGO concentration. Since hematite suffers from low electron mobility, a low absorption coefficient, high recombination rates and slow reaction kinetics, the incorporation of rGO in the hematite can overcome such limitations due to graphene's exceptional properties. Using the first method, the rGO incorporation results in a photocurrent density increase from 0.56 to 0.82 mA cm(-2) at 1.23 VRHE. Our results indicate that the rGO incorporation in the hematite photoanodes shows a positive effect in the reduction of the electron-hole recombination rate.