Toward preparation of large scale and uniform mesoporous BiVO4 thin films with enhanced photostability for solar water splitting

Abstract

The preparation methods of photocatalyst thin films play a critical role in increasing their efficiency. Ease of fabrication, the ability to commercialize, production on a large scale, reproducibility, and preparing the layers with stable performance are some of the most important criteria for a synthesis method to prepare a high-performance phot-electrode. A straightforward, cost-effective and reproducible hot spin coating (HSC) method was introduced in this work, to achieve these goals for BiVO4 thin films. The most important HSC parameters, namely substrate revolution speed (ωs), substrate temperature (Ts), and combustion time (Ct), were investigated systematically. The BiVO4 thin films prepared via the HSC method under the optimized parameters of ωs = 1200 rpm, Ts = 200 °C, and Ct = 15 s exhibited a uniform mesoporous surface texture (average pore diameter of 13.4 nm) and high adhesion (5B) to the substrate. Interestingly, the HSC method was capable of preparing super-hydrophilic BiVO4 layers on a large scale (tested up to 8 × 8 cm2) without any surface pinholes. The practical application of the obtained layers was examined inside a photoelectrochemical (PEC) cell. The optimized BiVO4 electrode generated a remarkable and robust photo-current density of ∼500 μA/cm2 without any change after 30 days. The preparation of BiVO4 thin films with such interesting properties via the facile HSC method makes it a promising technique to prepare highly efficient photo-anodes for practical use on a large scale.