Facile synthesis of Zn3(VO4)2/FeVO4 heterojunction and study on its photocatalytic and electrochemical properties

Bismuth vanadate/MXene (BiVO4/Ti3C2) heterojunction composite: enhanced interfacial control charge transfer for highly efficient visible light photocatalytic activity

We have synthesized BiVO4/Ti3C2 nanocomposite via a low-cost hydrothermal method and investigate its photocatalytic degradation activity against monoazo (methyl orange) and diazo dye (Congo red) in an aqueous solution under visible light. The physiochemical characterization exhibited that the addition of MXene in pristine BiVO4 nanocomposite led to an increase in specific surface area and reduction in optical band gap energy. MXene also helps in enhancing visible light response via a higher electron-hole pair generation rate and long lifetime. The synthesized BiVO4/Ti3C2 heterojunction composite exhibited 99.5 % degradation efficiency within 60 min for Congo red and 99.1 % for methyl orange solution in 130 min owed to a large specific surface area (1.79 m2/g), reduced band gap (1.99 eV), and low recombination rate of charge carriers. The chemical mechanism for BiVO4/Ti3C2 nanocomposite proposes that Ti3C2 role-plays as electron capture because of the higher potential of MXenes, tuning band gap energy which paves the way to excellent photocatalytic action. This work opens a new basis for developing Ti3C2 based promising and inexpensive co-catalyst for efficient solar utilization in photocatalytic-related applications in the future.

Construction of 1T-MoS2 quantum dots-interspersed (Bi1-x Fe x )VO4 heterostructures for electron transport and photocatalytic properties

The present study reports trigonal phase molybdenum disulfide quantum dots (MoS2/QDs)-decorated (Bi1-x Fe x )VO4 composite heterostructures. Initially, (Bi1-x Fe x )VO4 heterostructure nanophotocatalysts were synthesized through the hydrothermal method decorated with 1T-MoS2 via a sonication process. 1T-MoS2@(Bi1-x Fe x )VO4 heterostructures were characterized in detail for phase purity and crystallinity using XRD and Raman spectroscopy. The Raman mode evaluation indicated monoclinic, mixed monoclinic-tetragonal and tetragonal structure development with increasing Fe concentration. For physiochemical properties, SEM, EDX, XPS, PL, EPR, UV-visible and BET techniques were applied. The optical energy band gaps of 1T-MoS2@(Bi1-x Fe x )VO4 heterostructures were calculated using the Tauc plot method. It shows a blue shift initially within a monoclinic structure then a red shift with an increase of Fe concentration. 1T-MoS2@(Bi40Fe60)VO4 with 2 wt% of 1T-MoS2-QDs carrying a mixed phase exhibited higher photocatalytic activity. The enhanced photocatalytic activity is attributed to the higher electron transportation from (Bi1-x Fe x )VO4 surface onto 1T-MoS2 surface, consequently blocking the fast electron-hole recombination within (Bi1-x Fe x )VO4. 1T-MoS2 co-catalyst interaction with (Bi1-x Fe x )VO4 enhanced the light absorption in the visible region. The close contact of small 1T-MoS2-QDs with (Bi1-x Fe x )VO4 develops a high degree of crystallinity, with fewer defects showing mesoporous/nanoporous structures within the heterostructures which allows more active sites. Herein, the mechanism involved in the synthesis of heterostructures and optimum conditions for photocatalytic degradation of crystal violet dye are explored and discussed thoroughly.