Mg-Doped Hematite Nanoparticle Arrays Coated with CoPi Thin Films for Solar Water Oxidation

As a promising candidate for photoelectrochemical water decomposition, a-Fe2O3 has been plagued by low actual quantum efficiency and weak stability. In this work, we prepared an a-Fe2O3 photoanode with Mg doping and cobalt-hydroxyl-phosphate (CoPi) coating. Compared to a-Fe2O3, the CoPi/Mg-Fe2O3 photoanode exhibited remarkably enhanced activity of photoelectrochemical water splitting. The photocurrent density of the CoPi/Mg-Fe2O3 photoanode was 1.30 mA cm(-2) at 1.23 V vs RHE, which was around 3.51 times higher than that of a-Fe2O3 (0.39 mA cm(-2)). In addition, the CoPi/Mg-Fe2O3 photoanode demonstrated good stability, and the photocurrent density produced by the CoPi/Mg-Fe2O3 photoanode did not decrease significantly after 24 h of light irradiation. The efficiencies of bulk charge separation and surface charge injection of the CoPi/Mg-Fe2O3 photoanode were greatly increased through Mg doping and CoPi coating, which significantly improved its performances of photochemical water splitting.

Automated summary

In this study, an a-Fe2O3 photoanode with Mg doping and cobalt-hydroxyl-phosphate (CoPi) coating was prepared and showed significantly improved activity of photoelectrochemical water splitting compared to pure a-Fe2O3. The CoPi/Mg-Fe2O3 photoanode exhibited a photocurrent density of 1.30 mA cm(-2) at 1.23 V vs RHE, which was 3.51 times higher than that of a-Fe2O3 (0.39 mA cm(-2)). Moreover, the CoPi/Mg-Fe2O3 photoanode demonstrated good stability, maintaining its photocurrent density after 24 hours of light irradiation. The enhanced performances of photochemical water splitting were attributed to the increased efficiencies of bulk charge separation and surface charge injection through Mg doping and CoPi coating.