Highly efficient visible-light driven dye degradation via 0D BiVO4 nanoparticles/2D BiOCl nanosheets p-n heterojunctions.

The construction of hybrid heterojunction photocatalysts is an effective strategy to improve the utilization of photogenerated carriers and photocatalytic activity. To enhance the separation distance of photogenerated carriers and accelerate the effective separation at the heterojunction of the interface, a unique 0D-2D hierarchical nanostructured p-n heterojunction was successfully fabricated in this work. BiOCl (BOC) nanosheets (p-type) were in situ grown on BiVO4 (BVO) nanoparticles (n-type) using the microemulsion-calcination method for highly efficient visible-light-driven organic dye degradation. Compared with pure BVO (the degradation rate of rhodamine B (RhB): about 32.0% in 55 min, the mineralization rate: 24.9% in 120 min), the RhB degradation rate can reach about 99.5% in 55 min and the mineralization rate of 62.1% in 120 min by utilizing BVO/25%BOC heterojunction photocatalyst under visible light irradiation. Various characterizations demonstrate that the formation of BVO/BOC p-n heterojunction greatly facilitates photogenerated carriers separation efficiency. Meanwhile, the results of the scavenging experiments and electron spin resonance tests indicate that ·O2- and h+ are the prominent active species for Rh B degradation. In addition, possible degradation pathways for Rh B were proposed using LC-MS tests. This work proves that building low dimensional p-n heterojunction photocatalysts is a promising strategy for developing photocatalysts with high efficiency.

Effect of water-oil ratio on the photocatalytic performance of visible light-active BiVO4 nanoparticles prepared by inverse microemulsion-calcination method.

Nowadays, nano-photocatalysts (NPs) have become the research focus in the field of photocatalysis due to their excellent photocatalytic activity, and microemulsion is an effective method to prepare high-efficiency nano-photocatalysts. Here, BiVO4 NPs with high efficiency under visible light were prepared by a combination of reverse microemulsion method and calcination method. XRD, SEM, TEM, XPS, DRS, PL, BET and other characterization tests were used to comprehensively explore the influence of water-oil ratio on the physicochemical properties of the catalysts. The results show that BiVO4 NPs of monoclinic scheelite with high crystallization degree can be obtained by this method. The microscopic morphology, specific surface area and total pore volume of BiVO4 NPs are significantly affected by the water-oil ratio. It is difficult to obtain BiVO4 NPs with small particle size and uniform dispersion under the condition of too low or too high water-oil ratio. Meanwhile, the photogenerated carrier recombination efficiency of the catalyst is significantly improved, thus reducing the photocatalytic activity of the catalyst. Strikingly, the BiVO4 NPs obtained under the condition of water-oil ratio is 20 exhibited well-dispersed nanospheres with diameters ranging from 80 to 100 nm. It has the highest photocatalytic activity due to its high crystallinity, large specific surface area and total pore volume and relatively low photogenerated carrier recombination efficiency. Under visible light irradiation, the degradation efficiency of RhB can reach 97.69% in 100 min, and the rate constant is 0.03253 min-1.

Spatial distribution characteristics and influencing factors of organic carbon in sediments of Tongshun River riparian zone.

The riparian zone is closely related to the surrounding environment, and it is important to find out the distribution characteristics of organic carbon in the sediment of the riparian zone. In this paper, the distribution of organic carbon in sediments and its influencing factors were analyzed in the riparian zone of small watershed. The results show that the distribution of organic carbon was significantly related to the lithology of sediment, and the sedimentary environment determined the content of organic carbon in sediment. In shallow sediments, organic carbon changed significantly with depth, and redox conditions were the main influencing factors. When the environment changed from oxidation condition to reduction condition, both the mineralization of organic carbon and the change of iron oxide morphology would change the stabilizing effect of organic carbon, thus affecting the distribution of organic carbon. In addition, under the influence of flood, the organic carbon in the riparian sediments changed with the distance to the river in the horizontal direction.