Size dependence of nanosheet BiVO4 with oxygen vacancies and exposed {0 0 1} facets on the photodegradation of oxytetracycline

Abstract A new type of promising nanosheet BiVO4 with reduced dimension, sufficient oxygen vacancies (OVs) concentration, and exposed {0 0 1} crystal facets for oxytetracycline removal were synthesized via hydrothermal method. The prepared samples were fully characterized. SEM, HR-TEM, XRD, and BET analyses determined the existence, proportion, and intensity of the exposed {0 0 1} facets on BiVO4 nanosheet. DRS and LSV were used to investigate the photoelectric properties of the samples. In addition, the XPS, solid EPR, and PL characteristics were examined to explore the change in OVs concentration of the as-synthesized BiVO4 nanosheet when compared with reported BiVO4 layer. In particular, BiVO4 lamella within the thickness of ten nanometer (tBV200) had notable relative intensity of dominant {0 0 1} facets in XRD results, thereby enhancing the internal electric field to facilitate the formation and separation of photogenerated electrons in the PL test. Nevertheless, tBV200 had a greater OVs density and a relatively larger percentage of dominant {0 0 1} facets, which could be ascribed to its remarkably enlarged BET surface area and significantly reduced size compared with the reported BiVO4 layer within the thickness of a hundred nanometer (hBV200). tBV200 showed enhanced photocurrent (1.083 mA/cm2) in the LSV test, and this value was 1.33 times higher than the larger counterpart. This finding demonstrated outstanding photoelectron conversion efficiency. The best oxytetracycline degradation ratio (95.83%) and TOC removal ratio (89.55%) were obtained with the tBV200, which involved the active species O2− and h+. The excellent photoelectric capability, photocatalytic properties, and stability of tBV200 novel catalyst could be attributed to the high number of active sites, as well as the improved formation, transportation, and collection of photogenerated charges. These advantages are related to the characteristics of reduced thickness, well-crystallized and enlarged dominant {0 0 1} facets, and enhanced OVs intensity in tBV200.