Rationally designed CdS/Ti₃C₂ MXene electrocatalysts for efficient CO₂ reduction in aqueous electrolyte

MXene-based catalysts have shown excellent activities in various electrocatalytic reactions due to the two-dimensional structure, good electrical conductivity and abundant surface functional groups. However, because of the competitive reactions in aqueous electrolytes, the application of MXene materials in CO₂ electroreduction still remains a challenge. Herein, a simple strategy was developed for the design of high efficient and stable CO₂ electroreduction catalysts in aqueous electrolyte. A series of MXene composite catalysts were successfully synthesized by densely coating sulfur vacancy-rich CdS nanoparticles on Ti₃C₂. The two-dimensional MXene skeleton with good conductivity delivers fast electron transfer, improves the electrolyte infiltration and increases the electrochemical surface area. CdS nanoparticles with abundant sulfur vacancies are attached on Ti₃C₂ MXene surface, providing active sites for CO₂ reduction. Faraday efficiency of the by-product hydrogen could be significantly reduced by minimizing the surface-exposed Ti of the catalyst. Benefited from these merits, the optimal CdS/Ti₃C₂ possesses fast CO₂ electroreduction reaction kinetics, exhibiting a high CO Faraday efficiency of 94% at -1.0 V vs. reversible hydrogen electrode. This work provides a feasible pathway for the design of MXene-based catalysts of CO₂ electroreduction.