Understanding the synergistic role of Pt-mediated MoO3 photoanode with self-photorechargeability during illuminated and non-illuminated conditions: A combined experimental and density functional theory study

Abstract Here, we synthesize a functional MoO3 photoanode with self-photorechargeability through aerosol-assisted chemical vapour deposition. The role of platinum co-catalyst in Pt-mediated MoO3 photoanode (Pt/MoO3) was investigated to improve and maintain its charge density to enable photoelectrochemical water oxidation under non-irradiated condition. Raman spectroscopy and X-ray diffraction analyses showed that the orthorhombic phase of MoO3 was formed with significant Raman diffraction peaks and crystal planes were grown in the (0k0) crystallographic orientation for better charge storage capacity in MoO3 photoanodes, respectively. Furthermore, the chronoamperometry measurements of the Pt/MoO3 photoanode revealed that both current and charge densities were improved by 29 times and 94 times, respectively, than the bare MoO3 photoanode. This is attributed to the presence of Pt co-catalyst, which acts as an effective electron sink in inhibiting the recombination of photogenerated charge carriers. A density functional theory simulation was then used to validate the experimental findings and fundamental mechanisms of self-photorechargeability in Pt/MoO3 photoanodes. It was found that the distinct characteristic of slow decay in charge density of Pt/MoO3 photoanode is due to the formation of alkali cation/metal layer, where the intercalated photogenerated electrons require a higher energy to overcome the energetic barrier of the alkali cation/metal layer.