Self-Flux Method in Sputtered BiVO4 Films for Enhanced Photoelectrochemical Performance

Bismuth vanadate (BiVO4) is a well-sought candidate as a photoanode in photoelectrochemical (PEC) water splitting. The mismatch between the V/Bi ratio affects the photocatalytic efficiency of BiVO4 films fabricated using the large-area sputtering method. We adopt a facile method to finely control the V/Bi ratio in sputtered films by changing the oxygen partial pressure. We observed the formation of various phases, with a change of V/Bi ratio in the films ranging from 0.5 to 2, and found that the segregated V2O5 acts as a self-flux in improving the crystallinity of BiVO4, resulting in a long carrier lifetime. With the prolonged carrier lifetime from 0.098 to 0.211 ns, the optimized films realize a photocurrent density of 1.97 mA/cm(2) at 1.23 V versus reversible hydrogen electrode. However, V2O5 itself does not exhibit a lifetime comparable to BiVO4, which implies that an excess amount of V2O5 is detrimental to PEC performance. These findings point to the significance of a slightly V-rich growth environment for advancing the PEC performance of BiVO(4 )materials. Our work provides insights into the growth of high-quality crystals by controlling composition in other multielement oxides.

Automated summary

Bismuth vanadate (BiVO4) is a promising photoanode material for photoelectrochemical (PEC) water splitting. In this study, we control the V/Bi ratio in sputtered films by changing the oxygen partial pressure, leading to the formation of different phases. The addition of segregated V2O5 improves the crystallinity and carrier lifetime of BiVO4, resulting in enhanced PEC performance.