Co3O4-Decorated Hematite Nanorods As an Effective Photoanode for Solar Water Oxidation

In this Article, we report a strategy to perform in situ incorporation of oxygen evolution catalyst, Co3O4, during hydrothermal growth of Fe2O3 nanorod arrays. It was found that the highest photocurrent increase and onset potential shift was observed with 5% Co2+. The photocurrent density increases from 0.72 for the pristine Fe2O3 nanorod to 1.20 mA/cm2 at 1.23 V versus RHE (i.e., 67% improvement) with 5% Co2+ added. Concomitant with this improvement was a shift in the onset potential by ∼40 mV and improvements in incident-photon-to-current efficiencies and oxygen evolution. Hematite photoanodes with in situ deposition of Co3O4 nanoparticles showed better performance than those prepared by ex situ procedures because of high surface roughness, larger Co3O4/hematite interfacial area, and smaller Co3O4 particle size.