| Nowadays,metal sulfide semiconductor nanomaterials as the research hotspots of physics,chemistry and materials science have been widely applied in some frontier fields of solar cells,catalysis and sensors due to their excellent electronic structure and unique physicochemical properties.In view of the existing problems of metal sulfide nanomaterials in terms of low active surface area and poor electronic conductivity,as well as the effecct of structure on the active site number,electron transfer rate and catalytic reaction kinetics,in this paper,we synthesize several typical metal sulfide nanomaterials,including the binary indium sulfide(In2S3),zinc sulfide(Zn S)and molybdenum sulfide(Mo S2),as well as ternary copper indium sulfide(Cu In S2,CIS)via a facile and controllable liquid-phase synthesis method.The crystal phase/defect structure,surface morphology and size of as-synthesized metal sulfides are well tuned by adjusting the reaction parameters,doping the non-metallic elements and constructing the hetero-structure,which effectively optimize the energy band,surface and electronic structure for superior catalytic performance.Moreover,the formation mechanisms of unique nanostructures are revealed,and some universally new methods for material synthesis and structure control are proposed,which enriches the scientific content of material preparation.Based on the deep recognization for the catalytic nature,the correlation among synthesis strategy,material structure and catalytic performance is further established,which provides strong theoretical and data supports for the development of novel and efficient catalysts.The specific work is as follows.(1)Polytypic CIS nanosheets were synthesized via a novel hot-injection system using oleic acid and liquid paraffin as the reaction media.By increasing the reaction temperature and decreasing the initial[Cu]/[In]molar ratio,the crystal phase of CIS was converted from zincblende to zincblende/wurtzite and chalcopyrite/wurtzite types,respectively.The formation mechanism of polytypic CIS NSs was proposed.Compared with zincblende-CIS,the polytypic CIS exhibits significantly enhanced light-absorption ability and visible-light-driven photocatalytic performance,originating from the rational hetero-crystalline interfaces that promote the transfer and separation of photogenerated carriers.Moreover,indium-rich chalcopyrite/wurtzite polytypic CIS has the decreased surface defect states,which effectively inhibits the recombination of photo-generated carries,further enhancing the photocatalytic and photoelectrochemical activity.(2)Two kinds of unique In2S3 nanostructure,i.e.,ultrathin nanosheets and hollow nanoparticles were synthesized via hot-injection method and surfactant-free hydrothermal route,respectively.For the two different synthesis strategies,the effect of reaction parameters on the crystal structure,morphology,size,and optical properties of as-obtained In2S3 was studied.Furthermore,the adsorption and visible-light-driven photocatalytic performance of two kinds of In2S3 nanostructure for methylene blue(MB)were comparatively studied.Results indicate that In2S3ultrathin nanosheets shows excellent photocatalytic performance due to the strong quantum confinement effect resulting from the ultra-thin thickness(less than 1.2 nm).In contrast,In2S3 hollow nanoparticles exhibit efficient adsorption and photocatalytic degradation for the concentrated MB dyes(100 mg L–1),being attributed to the large specific surface area(324.6 m2 g–1)and high light absorption efficiency.(3)Zn S/Ag2S core/shell heterostructure was synthesized via a facile two-step hydrothermal process.Firstly,Zn S microspheres were prepared using PEG-400 as the surfactant.And then,Ag2S nanoparticles were uniformly nucleated on the surface of Zn S microspheres via an ion exchange process.The effect of Ag2S molar ratio on the morphology,optical properties and photocatalytic activity of Zn S/Ag2S composite microsphere was discussed.These results indicate that the photocatalytic efficiency of Zn S/Ag2S composite is much higher than that of pure Zn S and Ag2S under solar-simulated light irradiation,which can be considered that the construction of rational heterostructure can rapidly separate photogenerated electrons and holes.Furthermore,the photocatalytic degradation efficiencies of Zn S/Ag2S heterostructure are enhanced with the assistance of hydrogen peroxide.(4)A hierarchical composite catalyst with N-doped Mo S2 ultrathin nanosheets epitaxially grown on the outside of N-doped multiwalled carbon nanotubes(N-Mo S2@N-CNT)was constructed via a facile and controllable one-pot solvothermal route.After N incorporation into Mo S2,the expanded interlayer spacing and rich sulfur-vacancies were obtained,which increase catalytically active sites exposed on the basal planes/edges of N-Mo S2.Simultaneously,N dopants into CNTs were found not only to favor the in-situ growth of Mo S2 NSs,but also to improve the electronic conductivity of composite catalyst.Furthermore,the correlation among N doping content,surface/electronic structure and HER activity of N-Mo S2@N-CNTs catalysts is demonstrated.Owing to the structural advantages and synergistic effect,N-Mo S2/N-CNTs hierarchical composite with the optimized N-doping content exhibits superior HER activity,in terms of low onset overpotential(84 m V),small Tafel slopes(40.5 m V dec-1)and excellent cycle stability.(5)A stable three-dimensional network hetero-structure of 1T-rich Mo S2nanosheets(NSs)vertically grown on nitrogen-doped reduced graphene oxide(NG)was constructed via a surfactant-free hydrothermal method.Remarkably,N dopants into graphene framework simultaneously promote the in-situ growth of sulfur vacancy-rich Mo S2 NSs and induce the crystal phase transition of 2H-to 1T-Mo S2,reaching a high 1T-phase proportion of ca.81.7%,which would be beneficial to expose more active sites and improve electronic conductivity for electrocatalytic reaction.The excellent synergistic effect makes 1T-rich Mo S2/NG(MNG)composite exhibit significantly enhanced electrocatalytic oxidation activity towards ascorbic acid(AA)than that of MG.Furthermore,the superior AA sensing performance of MNG catalyst is demonstrated.This novel sensor was successfully used in the determination of AA in real samples. |
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