Dual active sites fabricated through atomic layer deposition of TiO2 on MoS2 nanosheet arrays for highly efficient electroreduction of CO2 to ethanol

Electrochemical reduction of CO2 to ethanol through renewable electricity is highly desirable but still challenging. Here, we demonstrated that TiO2/MoS2 nanosheet arrays synthesized through atomic layer deposition (ALD) of TiO2 on the surfaces of MoS2 nanosheet arrays enabled the electrochemical CO2 reduction reaction (CO2RR) toward ethanol. As a result, 50% faradaic efficiency (FE) for ethanol was achieved over the obtained electrocatalyst at only -0.60 V versus the reversible hydrogen electrode (RHE) in CO2-saturated 0.5 M KHCO3 aqueous solution, which ranks as the best electrocatalysts for the CO2RR to ethanol. The experimental results and theoretical calculations showed that Mo and Ti dual active sites formed on the interfaces of TiO2 and MoS2 could adjust CO binding energy and promote the CO-CO coupling reaction and its subsequent transformation. A new regulatory mechanism of the CO coupling reaction and the possible reaction path were proposed based on experimental results and density functional theory (DFT) calculations.