In recent years, BiVO4 has been regarded as one of the most promising metal oxide photoanode candidates for water splitting. In JCAP, we have successfully developed sputtering synthesis effort for making high quality, uniform and dense thin film BiVO4 not only for potential large scale application, but also for fundamental electronic characterization such as transient absorption (TA), resonant inelastic X-ray scattering (RIXS) and so on. From our characterization results, we confirm that the electron conductivity is fairly poor in BiVO4 and probe the origin of it. To overcome this intrinsic problem of BiVO4 and make it more viable for our wireless water splitting device, we use several approaches.
We are able to introduce dopants of W and Mo into BiVO4 by co-sputtering. Influence of different doping materials and doping levels will be discussed in the presentation. We are also going to show thermal conductivity measurement, TA and RIXS analysis explore the roles of the dopants in improving electronic properties of BiVO4.
We use H2 treatment to make the film more O deficient and thus more n-type conductive. Again, related PEC and electronic characterization will be shown in the presentation.
The addition of underlayer/hole blocking layer to facilitate charge separation at the back.
The integration of OER catalysts to rapidly extract holes from the surface instead of recombining with electrons. We will compare the traditional Co based catalysts for mild pH operation condition with the Ni-Fe (Ce) based catalyst for extreme basic operation condition. We will also discuss the possibility to stabilize BiVO4 under extreme conditions.