Enhanced photoelectrochemical performance of electrodeposited hematite films decorated with nanostructured NiMnOx

In the present work, we report a novel nickel-manganese oxide (NiMnOx) decorated hematite (α-Fe2O3) photoanode for efficient water splitting in a photoelectrochemical (PEC) cell. The photoanodes are prepared by a two step electrodeposition process. NiMnOx loading on the hematite surface is varied by changing the electrodeposition time. The NiMnOx loaded α-Fe2O3 photoanodes are characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, UV-Vis absorption and photoluminescence spectroscopy. The results demonstrate that the NiMnOx decorated α-Fe2O3 photoanode exhibits excellent photoelectrochemical activity. The α-Fe2O3/NiMnOx photoanode, where NiMnOx was coated for 200 s, shows a maximum photocurrent of 2.35 mA cm-2 at an applied potential of 0.23 V vs. the Ag/AgCl reference electrode. There is a large shift in the onset potential towards the cathodic region also observed. The photoconversion efficiency is calculated which is around 0.85% at 0.23 V vs. Ag/AgCl. The superior PEC performance of NiMnOx decorated α-Fe2O3 photoanodes can be explained by a combined effect of better water oxidation on the hematite surface and efficient separation of photogenerated electron-hole pairs on its surface due to NiMnOx modification. © The Royal Society of Chemistry 2016.