Study On Amorphous MoSe₂ Photocatalyst Degrading Medical Dirt

Two-dimensional transition metal chalcogenide compounds have been widely used in the field of photocatalysis.Mo Se₂as a typical representative,narrow band gap characteristics make it as an important candidate material for photocatalysts.Due to the constraint of rare active sites,high photogenerated electron recombination rate and poor photo responsiveness,researchers are committed to improving photoelectric performance through methods such as doping,crystal adjustment,and heterojunction construction.In this paper,non-stoichiometric amorphous Mo Se_xis used as the main material,and the photocatalytic performance is further improved by doping and constructing a heterojunction.Amorphous Co-doped Mo Se_xnanostructure and nano-heterostructure of amorphous Mo Se_xand Cd Se were synthesized by simple hydrothermal method,and the efficiency was verified through experiments.The details are as follows:（1）In this study,amorphous Co-doped Mo Se_x（Co-Mo Se_x）sample was synthesized by low-temperature hydrothermal method.There were three types of unsaturated Se-Se bonds found in Co-Mo Se_xby Raman:bridging diselenide,shared diselenide,and terminal diselenide.Photocatalytic experimental results revealed that the degradation rate of Co-Mo Se_xto methylene blue was 96.3%,the degradation rate of amorphous Mo Se_x（a-Mo Se_x）was 61.6%,and the degradation rate of crystalline molybdenum selenide（c-Mo Se₂）was 23.2%.Co-Mo Se_xis used to degrade tetracycline hydrochloride with an efficiency of 83.1%and an inactivation efficiency of E.coli of81.3%.Furthermore,it was found that the band gap of Co-Mo Se_xphotocatalyst was reduced 0.15 e V compared to the a-Mo Se_xphotocatalyst.The photocatalytic activity of Co-doped Mo Se_xwas enhanced by increasing unsaturated Se atoms active sites,reducing the racombination of photogenerated electron-hole pairs,and improving the light utilization.（2）Cd Se/a-Mo Se_xheterojunction with excellent photocatalytic performance was successfully synthesized by hydrothermal method and grinding method.Different from traditional crystalline molybdenum selenide,amorphous molybdenum selenide provides more active sites for photocatalytic reactions.A unique heterostructure was formed by combining Cd Se and amorphous molybdenum selenide.The Cd Se/a-Mo Se_xsample showed the best photocatalytic activity,the final degradation efficiency of MB under visible light was 97.3%,while the Cd Se and Mo Se_xsamples finally degraded MB efficiency of 58.8%and 67.0%.The balanced Fermi level in the Cd Se/a-Mo Se_xheterostructure energy band reduces the band gap of the system and expands the photoresponse range.At the same time,the heterojunction interface effectively separates the photogenerated electron pairs generated in the photocatalytic process and suppresses photogenerated electrons recombination,so that the photocatalytic performance of Cd Se/a-Mo Se_xheterojunction has been improved.