Solar Water Splitting Combining a BiVO4 Light Absorber with a Ru-Based Molecular Cocatalyst

We demonstrate here for the first time the photoelectrochemical properties of a BiVO4 photoanode in conjunction with a molecular catalyst. When the Ru-based molecular catalyst (RuCat) is coupled to a BiVO4 light-absorber the performance of this photoanode improves particularly in the low-bias region (<1.0 V vs RHE). The RuCat-BiVO4 photoanode shows a higher photocurrent than CoPi-BiVO4 under front illumination, and a 0.1 V more cathodic onset potential. The former can be partly explained by the low light absorption of the RuCat (<5% light absorption in the UVvisNIR range). For the latter, we propose that the linkers in the RuCat reduce the surface recombination in BiVO4 to a greater extent than CoPi. Finally, we observe that the fill factor of the RuCat-BiVO4 JV characteristic improves after the stability test. The results presented herein not only show the feasibility and potential of the solid state/molecular heterojunctions but also represent a proof of principle to improve conventional all-solid-state systems such as CoPi-BiVO4.