(513ew) Solvothermal Synthesis of Defect-Rich Mixed 1T-2H MoS2 Nanoflowers for Enhanced Hydrodesulfurization

Molybdenum sulfide (MoS₂) has been used extensively for HDS for several decades, which can be further improved towards more effective catalysts due to its distinctive phase-engineering nature. Herein, 1T-2H mixed-phases MoS₂ nanoflowers with tunable defects have been synthesized and used in HDS reaction. A facile solvothermal method using water, ethanol and glycerin has been developed for generating stable mixed 1T-2H MoS₂, in which the vacancies of both S and Mo have been produced. The data of XRD, SEM and TEM revealed the formation of MoS₂ nanoflowers, which was formed by the irregular aggregation of the ultrathin nanosheets. A lot of vacancy defects on the basal planes were shown in the HRTEM images, which had a positive effect on exposing active sites.Detailed characterization based on XPS and EPR showed that S and Mo vacancies coexisted on the samples. In the Raman spectra of the as-prepared MoS₂, the peaks of E_2g¹, A_1g, J₁, J₂, J₃ were observed, indicating the existence of 1T-2H mixed phase. XPS analyses in the core level peak regions of Mo 3d and S 2p further confirmed the presence of both 2H-phase and 1T-phase. 1T-MoS₂ can provide more active sites than 2H-MoS₂, and it is beneficial to the catalytic reaction. TPR results show greatly affected H₂ adsorption behavior of MoS₂ by engineering of the phases and defects. Dibenzothiophene (DBT) was utilized as the model to evaluate the performance of HDS of the catalyst. In the HDS of DBT, the defect-rich mixed 1T-2H MoS₂ exhibits high conversion (80%) and high hydrogenation (HYD) selectivity (89%), which was 10 times and 1.4 times those of the commercial MoS₂, respectively. Moreover, the as-synthesized MoS₂ was stable to maintain the initial activity and product selectivity in the harsh high-temperature reaction environment, as determined by XRD, Raman, and XPS.