Epitaxial synthesis of Ni-MoS₂/Ti₃C₂T MXene heterostructures for hydrodesulfurization

Hierarchical structures of 2D layered Ti₃C₂T MXene hold potential for a range of applications. In this study, catalysts comprising few-layered MoS₂ with Ti₃C₂T have been formulated for hydrodesulfurization (HDS). The support Ti₃C₂T was derived from MAX phases (Ti₃AlC₂) via a liquid-phase exfoliation process, while MoS₂ was obtained from synthesized aqueous ammonium tetrathiomolybdate (ATM). Furthermore, a series of catalysts with different architectures was synthesized by confinement of ATM and/or the promoter Ni in Ti₃C₂T at different mole ratios, through a thermal conversion process. The synthesized MoS₂/Ti₃C₂T and Ni-MoS₂/Ti₃C₂T catalysts were characterized using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), high-resolution transmission electron microscopy (HRTEM), and temperature-programmed reduction (TPR) measurements. The number of MoS₂ layers formed on the Ti₃C₂T support was calculated using Raman spectroscopy. The heterostructured few-layered MoS₂/Ti₃C₂T catalysts were applied in sulfur removal efficiency experiments involving thiophene. The active MoS₂ sites confined by the Ti₃C₂T enhanced hydrogen activation by proton saturation, and the electron charge stabilized the sulfur atom to facilitate hydrogenation reactions, leading to predominant formation of C₄ hydrocarbons. The Ni-MoS₂/Ti₃C₂T showed the best activity at a promoter molar ratio of 0.3 when compared to the other catalysts. In particular, it is evident from the results that ATM and Ti₃C₂T are potential materials for the in situ fabrication of hierarchical few-layered MoS₂/Ti₃C₂T catalysts for enhancing hydrodesulfurization activity in clean fuel production.