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

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 highperformance 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 (cos), substrate temperature (Ts), and combustion time (Ct), were investigated systematically. The BiVO4 thin films prepared via the HSC method under the optimized parameters of cos = 1200 rpm, Ts = 200 degrees 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 superhydrophilic BiVO4 layers on a large scale (tested up to 8 x 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 mu A/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.

Automated summary

The preparation of high-performance BiVO4 thin films using a straightforward and cost-effective hot spin coating method is described in this work. The optimized parameters resulted in uniform mesoporous films with high adhesion. The method was also capable of preparing large-scale superhydrophilic BiVO4 layers, exhibiting stable photo-current density in a photoelectrochemical cell.