Preparation And Photocatalytic Performance Of In₂Se₃ Quantum Dots

The new two-dimensional materialα-In₂Se₃ has high carrier mobility,suitable band gap,good stability,and ultra-thin layered structure,and shows great application potential in the field of photocatalysis.This paper first reported the preparation ofα-In₂Se₃ quantum dots（QDs）by liquid phase exfoliation method and characterized them in detail..The optical properties ofα-In₂Se₃ QDs were tested and analyzed,and their photocatalytic performance and mechanism were mainly investigated.First,the effects of different ultrasonic power and ultrasonic time on the morphology and particle size ofα-In₂Se₃ QDs were discussed,and the typical preparation parameters were determined as 450 W,6 h.XRD and Raman confirmed that the used In₂Se₃ crystal is rhombohedralαphase.SEM found that In₂Se₃ crystal has good crystallinity,and EDS confirmed that the content ratio of In and Se element is 2:3.Under TEM and AFM,α-In₂Se₃QDs were uniform in size,with an average particle size of 2.2±0.3 nm and an average height of 2.1±0.5 nm.HRTEM and SAED results showed thatα-In₂Se₃ QDs are rhombohedralαphase;XPS test showed thatα-In₂Se₃ QDs were slightly oxidized after being left in the air for one month.The results of optical absorption and PL showed that the band gap ofα-In₂Se₃QDs is 2.63 e V,an emission peak appeared at a wavelength of 825 nm,and the peak intensity was much lower than raw crystal.It was confirmed thatα-In₂Se₃ QDs have good photocatalytic performance through controlled experiments,in which Rh B degraded 48.9%after 60 min of light irradiation,which might be attributed to the small size providing more active sites and reducing the recombination of photogenerated carriers.Then the interfering factors of the photocatalytic performance ofα-In₂Se₃ QDs are studied,including the initial addition amount ofα-In₂Se₃QDs and solutions with different p H values.when the initial amount ofα-In₂Se₃ QDs was increased,photocatalytic effect was enhanced correspondingly.Photocatalytic performance was promoted in acidic solutions and suppressed in alkaline solutions.The cycle life test confirmed that the photocatalytic performance ofα-In₂Se₃ QDs decreased by 51.6%after being used for 4 times.The main problem is,due to the extremely small size,amount of QDs lost inevitably during each recycling process.This issue needs to be addressed in further study.Finally,the mechanism of photocatalytic degradation ofα-In₂Se₃ QDs was initially explored.By adding the scavenger,it was found that during the photocatalytic degradation of dyes byα-In₂Se₃ QDs,the main active substance is h⁺,followed by?O₂^-,and?OH only slightly effect.