Enhanced Selectivity and Uptake Capacity of CO₂ and Toluene Adsorption in Co_0.5M_0.33MoS₄ (M= Sb or Y) Chalcogels by Impregnated Metal Salts

The synthesis of metal chalcogenide aerogels Co_0.5M_0.33MoS₄ (M= Sb or Y) by the sol-gel method is reported. In this system, the building blocks [MoS₄]²⁻ chelated with Co²⁺ and (Sb³⁺) or (Y³⁺) salts in nonaqueous solvents forming amorphous networks with a gel property. The chalcogels obtained after supercritical drying have BET surface areas of 176 m² g⁻¹ (Co_0.5Sb_0.33MoS₄) and 145 m² g⁻¹ (Co_0.5Y_0.33MoS₄). Electron microscopy and physisorption studies reveal that the new materials are porous with wide pore size distribution and average pore width of 16 nm. These chalcogels show higher adsorption capacity of toluene vapor (Co_0.5Sb_0.33MoS₄: 387 mg g⁻¹) and (Co_0.5Y_0.33MoS₄: 304 mg g⁻¹) over cyclohexane vapor and high selectivity of CO₂ over CH₄ or H₂, Co_0.5Sb_0.33MoS₄ (CO₂/H₂: 80 and CO₂/CH₄: 21), Co_0.5Y_0.33MoS₄ (CO₂/H₂: 27 and CO₂/CH₄: 15). We also demonstrated that the impregnation of various metal species like Li⁺, Mg²⁺, and Ni²⁺ significantly enhanced the uptake capacity and selectivity of toluene and CO₂ adsorptions in the chacogels.