Single step aerosol assisted chemical vapor deposition of p–n Sn(ii) oxide–Ti(iv) oxide nanocomposite thin film electrodes for investigation of photoelectrochemical properties

Abstract

A homogeneous 1 : 1 solution of tetraisopropoxytitanium(IV) and [Sn(OAc)(dmae)]₂ precursors in toluene was used at 450 °C, under argon, to deposit p–n-type tin(II) oxide–titanium(IV) oxide nanocomposite thin film electrodes by a single step aerosol assisted chemical vapor deposition (AACVD) technique. Field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD), Raman scattering, energy-dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectrophotometry were conducted to characterize the thin film electrodes. The deposited thin film electrodes were tested for their applications in water photolysis. A comparison of the photoelectrochemical properties of the deposited SnO–TiO₂ composite electrodes with those of pristine TiO₂ and SnO electrodes fabricated from tetraisopropoxytitanium(IV) and [Sn(OAc)(dmae)]₂, respectively, indicates a higher photocatalytic activity as compared to pristine TiO₂. This is possibly due to the incorporation of p-type SnO, which effectively promoted the separation of photogenerated charge carriers to rectify electron transfer from SnO to TiO₂, leading to the separation of electron–hole pairs. The combined synergistic effect of p-type SnO and n-type TiO₂, flower-like morphology and augmented ability to absorb solar light produced a significantly enhanced photocurrent of ∼4.3 mA cm⁻² at 0.7 V vs. Ag/AgCl electrode. No obvious photocurrent decay was noted for prolonged stability measurements of up to 60 min under one sun illumination of 100 mW cm⁻². With such a facile synthetic strategy and enhanced performance profile, the resulting material provides inspiration for producing new p–n-type composite photoanodes for better PEC performance using similar strategies.