Hydrophobic and Electronic Properties of the E-MoS₂ Nanosheets Induced by FAS for the CO₂ Electroreduction to Syngas with a Wide Range of CO/H₂ Ratios

The electrochemical CO₂ reduction reaction (CO₂RR) to produce CO and H₂ (syngas) is a promising method for clean energy, but challenges remain, such as controlling the CO/H₂ ratios required for the syngas yield. Herein, hydrophobic exfoliated MoS₂ (H-E-MoS₂) nanosheets are fabricated from bulk MoS₂ by a cost-effective ball-milling method, followed by decoration with fluorosilane (FAS). H-E-MoS₂ is a cost-effective electrocatalyst capable of directly reducing CO₂ and H₂O for tuneable syngas production with a wide range of CO/H₂ ratios (from 1:2 to 4:1). In addition, H-E-MoS₂ shows a high current density, 61 mA cm⁻² at −1.1 V, and the highest CO FE of 81.2% at −0.9 V, which are higher than those of unmodified MoS₂. According to density functional theory calculations, FAS decoration on the surface of MoS₂ electrode can change the electronic properties of the edge Mo atom, which facilitates the rate-limiting CO-desorption step, thus promoting CO₂RR. Moreover, the hydrophobic surface of H-E-MoS₂ depressed the H₂ evolution reaction and created abundant three-phase contact points that provided sufficient CO₂. The hydrophobization of the electrode may provide an effective strategy for easily tuning the CO/H₂ ratio of syngas in a large range for the direct electroreduction CO₂ to syngas with an optimized CO/H₂ ratio.