Fabrication of pyramid-BiVO4/CdSe composite with controlled surface oxygen vacancies boosting efficient carriers’ separation for photocathodic protection

In order to solve the bottleneck problem of weak efficiency of carriers’ separation and transfer in BiVO4 photocatalyst, a novel pyramid-BiVO4 with sufficient oxygen vacancies was successfully synthesized via a low-temperature solvothermal method. By adjusting solution pH and adding SDBS surfactant, the prepared samples could have a variety of controllable morphologies and exposed {0 0 1} facets, which were determined by SEM, XRD, and BET methods. XPS O1s peak and ESR signals indicated that pyramid-BiVO4 exhibited higher oxygen vacancies concentration than others. Besides, CdSe quantum dots (QDs) were introduced to construct BiVO4/CdSe heterojunctions composite based photoanode to further promote solar harvesting and carrier separation. The photoelectrochemical experimental results showed that 304 stainless steel (304SS) coupled with 8V-BC photoanode showed an enhanced photocurrent density (608 μA·cm−2) and maximum potential drop (708 mV), which were equivalent to 5.06 times and 2.10 times that of the original BiVO4, respectively. Mechanism study illustrated that the ultra-high performance of the 8V-BC photoanode was attributed to the synergistic effect of enriched oxygen vacancies, exposed {0 0 1} facets, enlarged visible light absorption and larger specific surface area.