The confined growth of few-layered and ultrashort-slab Ni-promoted MoS₂ on reduced graphene oxide for deep-degree hydrodesulfurization

Hydrodesulfurization (HDS) is an essential process in clean fuel oil production, however, the huge challenge is the synthesis of the catalyst with plentiful active sites. Here, we have shown the design of few-layered, ultrashort Ni-Mo-S slabs dispersed on reduced graphene oxide (Ni-Mo-S/rGO-A) based on anchoring [PMo₁₂O₄₀]³⁻ clusters and Ni²⁺ on polyethyleneimine (PEI)-modified graphite oxide. Structural characterizations (transmission electron microscopy (TEM), X-ray absorption fine structure (XAFS), etc.) show that Ni-Mo-S slabs with predominant monolayer and partial substitution of edge Mo atoms by isolated Ni atoms have rich accessible edge Ni-Mo-S sites and high sulfurization degree. All virtues endow it with plentiful edge-active sites, and consequently, the enhanced performance for hydrodesulfurization of dibenzothiophene (DBT). The hydrodesulfurization proceeds via a more-favorable direct desulfurization (DDS) route with a reaction rate constant (k_HDS) of 48.6 × 10⁻⁷ mol·g⁻¹·s⁻¹ over Ni-Mo-S/rGO-A catalyst, which is 4.3 times greater than that over traditional Ni-Mo-S/Al₂O₃ catalyst and at the forefront of reported catalysts.