Preparation Of MoS₂/Oxide Nanocomposites And Investigation On Their Photocatalytic Performance

Molybdenum disulfide?MoS₂?is a semiconducting material with layered structure,narrow band gap,which can absorb the light with long wide wavelength and can be used as photocatalyst to degradate pollutants.Although MoS₂ based heterostructures have drawn increased attentions,the van der Waals forces with in MoS₂ layers makes it difficult to form strong chemical coupled interfaces with other materials.In this work,the surface of TiO₂were motified to facilitate formation of steady chemically bonded on MoS2/TiO2 interface via the dangling bonds,which can then be used to study the engineering of their interfacial electronic band structure.We have successfully synthesized the H₂Ti₃O₇ nanobelts by hydrothermal method,with several various post-treatments,such as?1?different modification methods,?2?different concentrations of NaOH,?3?the different content of MoS₂ on composites.And the heterostructures were investigated and representated the chemical composition,surface morphology and electronic structure.Finally,the effect of interfacial modification on photocatalytic degradation of Rhodamine B and electrocatalytic hydrogen evolution was studied.The experimental results showed the prepared and modified TiO₂ nanobelts are pure anatase.The surface morphology of TiO₂ nanobelts and MoS₂/TiO₂ heterostructures have more diffenence.The type II band alignments of MoS₂/TiO₂ are realized for all surface treatments.With the aid of high resolution transmission electron microscope?HRTEM?measurements,we found that the growth of MoS₂ has periodic trends with the internal structure of TiO₂,the in-plane structure shows that MoS₂[11?0]grows along the direction of TiO₂[001]and MoS₂[110]parallel to TiO₂[200]with every six units of MoS₂ superimposed on five units of TiO₂.The value band offset?VBO?is deduced based on the XPS measurements which play a key role on the photocatalytic performance.For the H₂SO₄-treated surface,both VBO and CBO are the largest;the electron and holes thus have the largest possibility to separate,and therefore,its photocatalytic activities should be the best.In addition,our photocatalytic activity measurements show that MoS2/TiO2-H exhibits the best photocatalytic activity as compared to the other samples,the degradation of the Rhodamine B in 80 min reached 84.7%,which is in line with our band alignment arguments.The superior photocatalytic activity of MoS₂/TiO₂-H could also be related to its more oxidized interface which leaves minimal recombination centers,therefore,inhibiting the recombination of electrons and holes.Finally,we performed the study of MoS₂/TiO₂ hybrids on their electrocatalytic hydrogen evolution reaction activities.Among all samples,MoS2/TiO2-H complexes exhibit the best HER activity,the onset potential is 153 mV and Tafel slop is 66.9 mV/dec.The enhanced activities was attributed to the abundant active sites at the interfaces as well as the synergistic effect between MoS₂ and TiO₂ which improved charge transfer efficiency.Our results emphasize the interfacial modification has an important influence on the interfacial electronic structure and the catalytic activities of MoS2/TiO2 heterostructures.