Carbon-based Perovskite Solar Cell Driven BiVO₄-based Photoelectrochemical Device For Water Splitting

In recent years,photoelectrochemical(PEC)technology has developed rapidly.Among them,solar cell-driven photoelectrochemical cell water splitting can realize solar energy to hydrogen energy conversion without external power supply,which is the future development trend of photoelectrochemical technology.Highly efficient and stable carbon-based perovskite solar cells(PSCs)and bismuth vanadate(BiVO4)with low cost,non-toxicity,high stability,suitable band gap(2.4 eV)and edge position can be used as the battery and photoanode material in photoelectrochemical cell.However,due to the short carrier diffusion distance and the poor charge separation efficiency,the practical photocurrent density of the BiVO4 photoanode is much lower than the theoretical maximum.Therefore,in this paper,two photoanodes based on BiVO4 were designed and prepared,and the performance of BiVO4 photoanodes was improved by co-doping and loading cocatalyst,respectively.The photoanode and the stabilized carbon-based PSC are integrated into the photoelectrochemical cell to realize the carbon-based perovskite solar cell-driven BiVO4-based photoelectrochemical cell to water splitting to produce hydrogen.The specific research progress is as follows:(1)A cobalt-molybdenum co-doped BiVO4 photoanode(Co,Mo:BiVO4)was prepared by metal-organic decomposition method by spin-coating.The synergistic effect of cobalt-molybdenum co-doping enhances the photoelectric conversion efficiency,charge separation efficiency and charge transport ability of BiVO4 photoanode,therefore effectively improves the PEC performance of BiVO4 photoanode,and the photocurrent density reaches 4.15 mA/cm2,which is four times higher than that of the undoped BiVO4 photoanode prepared by the same method.(2)A Co(OH)2/BiVO4 photoanode modified by cobalt hydroxide cocatalyst layer was designed and prepared.Under the modification of Co(OH)2 cocatalyst layer,the photocurrent density of Co(OH)2/BiVO4 photoanode reached 4.52 mA/cm2,which is nearly three times that of the unmodified BiVO4 photoanode prepared by this method.Using ABPE,IPCE,charge separation efficiency,EIS,polarization curve and other characterization and measure to study the reason of enhanced PEC performance.It is found that the loading of Co(OH)2 can improve the photoelectric conversion efficiency,reduce the photogenerated electron-hole pair recombination,improve charge separation efficiency,improve charge transport capability and reduce overpotential of BiVO4 photoanode,thereby improving PEC performance of BiVO4 photoanode.The prepared Co(OH)2/BiVO4 photoanode is connected in series with a stable carbon-based PSC and an electrode Pt to obtain a PV-PEC device.The PEC performance test results show that the PV-PEC device has an excellent performance,and obtain a stable photocurrent of 3.7 mA/cm2,which corresponds to a solar-to-hydrogen(STH)efficiency of 4.6%.The H2 and O2 evolution rates were 68 ?mol/cm2/h and 34 ?mol/cm2/h,respectively,and the faraday efficiency was 98%.In addition,the PV-PEC device has a good stability,after 10 h continuous illumination,the photocurrent density still maintained at 95%of the original value.