Aerosol-assisted facile fabrication of bimetallic Cr2O3-Mn2O3 thin films for photoelectrochemical water splitting

In the present studies, we demonstrate a simple and efficient method to fabricate Cr2O3-Mn2O3 composite thin films of immaculate homogeneity for photoelectrochemical (PEC) study. The clear THF solution of chromium(II) acetate hydrate and manganese(II) acetate tetrahydrate precursors in a 1 : 1 mole ratio was used in the aerosol-assisted chemical vapor deposition (AACVD) over FTO-coated glass substrates at the temperatures of 400, 450, and 500 degrees C in ambient argon conditions. X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray (EDX) analyses verified the formation of uniformly dispersed crystalline Cr2O3 and Mn2O3 phases. Direct optical band gaps at 2.50, 2.39, and 2.10 eV were measured at 400, 450, and 500 degrees C, respectively, from UV-Vis spectrophotometry. X-ray photoelectron spectroscopy (XPS) was carried out to investigate the oxidation state of the constituent elements in the prepared sample. PEC studies revealed that the synergistic effect appeared between Cr2O3 and Mn2O3 phases to facilitate the photo-oxidation of water, leading to a photocurrent density of 1.25 mA cm(-2) at 1.23 V vs. RHE. The Cr2O3-Mn2O3 composite thin film at 500 degrees C having a more compact structure shows the highest photocurrent density among all samples (0.32 mA cm(-2) at 1.23 V vs. RHE for 400 and 450 degrees C). Kinetics of the photocatalysis were investigated by electrochemical impedance spectroscopy (EIS), and a decrease in charge transfer resistance (Rct) was observed with the rise in deposition temperature. Deposition at different temperatures resulted in the improvement of photocatalytic activity, and these findings may lead to advantageous modification in the fabrication of thin film photoelectrodes for PEC water splitting.

Automated summary

In this study, a simple and efficient method was presented to fabricate Cr2O3-Mn2O3 composite thin films with immaculate homogeneity for photoelectrochemical (PEC) study. The results showed that the Cr2O3-Mn2O3 thin films had uniformly dispersed crystalline phases and demonstrated improved photocatalytic activity with the increase in deposition temperature. The highest photocurrent density was achieved at 500 degrees C, and the findings may contribute to the development of thin film photoelectrodes for PEC water splitting.