Abstract:
The efficient photocatalytic CO2 reduction to C-2 products remains a significant challenge due to sluggish multielectron transfer kinetics and C-C coupling. In this study, MoS2 nanocrystal-decorated Ti3C2 MXene heterostructured photocatalysts with varied loading concentrations have been synthesized using a facile hydrothermal method to enhance selective CO2 reduction to ethanol under visible light. The optimized MS-TC-10 heterostructure exhibits enhanced ethanol production (1633.8 mu mol/g), 1.8 times higher than that of bare MoS2, along with improved selectivity (58.12%) and quantum efficiency (1.5%). The broadening of Raman peaks, shifts in Ti 2p, Mo 3d, and S 2p binding energies in the XPS spectrum and a hybrid magnetic signature (sharp and broad peaks at g = 2.013 and 1.94, respectively) in EPR suggest intimate interfacial coupling and electronic interaction between the MoS2 and Ti3C2 MXene. Further, CO2-TPD and FTIR studies provided insights into the CO2 reduction pathway involving the formation of intermediates HCOO-, HCO3-, and carbonate species. CO2-TPD analysis of the MS-TC-10 heterostructure reveals two broad desorption peaks, corresponding to the weak and strong CO2 adsorption sites. The prominent high-temperature desorption peak indicates strong CO2 binding and thereby predominating C2H5OH formation. The overall improved activity is attributed to increased surface-active sites, broadened light harvesting, optimal band structure alignment, and efficient charge transfer across the MoS2-MXene interface. These factors collectively prolong charge carriers' lifetime, eventually suppressing their recombinations and facilitating a multielectron pathway for C-2 product formation. In brief, these results suggest strong CO2 adsorption, efficient photoinduced electron transfer from MoS2 to Ti3C2, and enhanced C-C coupling, enabling selective C-2 product formation. This work highlights electron-rich MXene-MoS2 architectures as a promising photocatalyst platform for solar-driven CO2 conversion to value-added chemicals.
