The effect of calcination time on the morphology and efficiency of BiVO4 films in order to use as solar decomposition of water

With the growth of science and technology and according to the vision of human knowledge, it is predictable that hydrogen will be the future fuel of human society. Chemical decomposition of water for fuel production through direct conversion of solar energy has been proposed as an interesting topic in science. In this experimental work, BiVO4 films as a photoanode were prepared by spray pyrolysis deposition method. Cobalt oxide was used as a cocatalyst and deposited on BiVO4 films by spin coating method. Five samples were calcined at 400oC for 1-5 hours to study the effect of calcination time on the morphology of BiVO4 films. Results showed that by increasing calcination time, the photo-current rises. This is because that by increasing calcination time, atoms were able to move into low energy sites at the surface and so separated individual nanoparticles could attach together to make better connectivity to the substrate. The XRD patterns also showed that there are no critical changes in the microstructure of the layers. The UV-VIS spectrum of samples shows an increase in photo absorption which is related to the variation in grain size of BiVO4 films.