Mesoporous titanium dioxide photoanodes decorated with gold nanoparticles for boosting the photoelectrochemical alkali water oxidation

Abstract

This work reports the photo-electrochemical enhancement of alkali water oxidation at mesoporous TiO2 (m-TiO2) photoanode prepared by evaporation-induced self-assembly (EISA) approach and photomodified with Au nanoparticle (Au/m-TiO2). The physicochemical characterizations of the modified photoanodes showed the uniform incorporation of gold nanoparticles having a diameter range of 3–5 nm into the mesoporous TiO2 substrate. The photo-electrochemical investigations demonstrate that the Au/m-TiO2 modified catalysts under the simulated solar light illumination exhibit excellent photoelectrochemical activity for alkali water oxidation and photocurrent density of 1.30 mA/cm2 has been achieved within the potential window of 0.1–1.7 V vs. reference hydrogen electrode (RHE), which is a 2.5 times higher photocurrent than that observed at bare m-TiO2 anode. An apparent oxygen evolution rate of 45.80 mmol/mg h was observed at a potential of 1.25 V vs RHE for Au/m-TiO2 which is significantly higher than that obtained for bare m-TiO2 (12.5 mmol/mg h). The mesoporous TiO2 materials modified with suitable metal nanoparticles via ex-situ photodeposition have shown substantial current gain during the photo-electrochemical water splitting reaction due to the boosting effect of the plasmonic nanostructure.