Negative Bias Potential Derived n-Si/Pt/Mo: BiVO4 Tandem Photoanode for Water Splitting

In theory, the utilization of a Z-scheme photogenerated carrier transport system has the potential to significantly enhance the photogenerated voltage for photoelectrochemical overall water splitting. However, thus far, there have been no previous reports on such phenomena with silicon-based semiconductor photoelectrodes. In this study, we fabricated an n-Si/Pt/Mo-doped BiVO 4 (Mo: BVO) sandwich-like film with an intermediate carrier transfer layer to prepare a silicon-based photoelectrode with an indirect Z-scheme system. Additionally, by leveraging the lattice distortion effect over Mo: BVO, we increased the fusion ability of the sandwich-like interface between different substances. For the first time, we achieved generation of anodic displacement current via negative voltage (−0.57 V (vs. RHE)), resulting in a photocurrent density of 1.56 mA/cm 2 and a photogenerated voltage five times higher than that of the n-Si/Mo: BVO structure. Through combining experimental approaches with theoretical calculations, it has been confirmed that this realization is attributed to the contribution of the transport process within the Z-scheme system in the n-Si photoelectrode. Furthermore, milliampere-level photocurrent under negative bias was observed for the first time on an n-Si photoelectrode, providing a novel approach for constructing silicon-based photoelectrodes for overall water splitting.