The CO₂ electroreduction reaction (CO₂ER) is a reliable pathway that enables a balanced carbon cycle for sustainable development strategies. There are several major challenges, such as selectivity, efficiency, and stability of the electrocatalysts that need to be addressed for the widespread application of this in the reduction of CO₂. Herein, we develop an oxide-modification of Cu_1.81S particles supported on multi-walled carbon nanotube (MWCNT) composites (Cu_1.81S@WMCNT-600-OD) through a facile in-situ crystallization strategy. This modification improves the electroreduction activity in the reduction CO₂ to formate with a low onset-potential of -0.47 V vs RHE (overpotential = 0.25 V). In addition, the material used in preparing this catalyst is widely accessible at low cost. Among the electrocatalysts tested, Cu_1.81S@WMCNT-600-OD exhibits a high CO₂ selectivity towards formate at an overpotential of 0.45 V with high faradaic efficiency (82 %) for nearly 20 h. Further investigations reveal that the needle-like dendritic structure formed during electrolysis is the likely source for the improved performance in CO₂ reduction. Therefore, this work provides low-cost, abundant, and efficient catalysts for CO₂ER and a facile pathway that improves the electrocatalytic performance.

CO ₂电还原反应（CO ₂ ER）是可靠的途径，可为可持续发展策略实现平衡的碳循环。存在许多主要挑战，例如电催化剂的选择性，效率和稳定性，这是在降低CO ₂的广泛应用中需要解决的。在本文中，我们通过一种简便的原位结晶策略，开发了负载在多壁碳纳米管（MWCNT）复合材料（Cu _1.81 S @ WMCNT-600-OD）上的Cu _1.81 S颗粒的氧化物改性。这种修改改善了减少CO的电还原活性₂与-0.47 V的低发病电位成甲酸盐VSRHE（过电势= 0.25 V）。另外，用于制备该催化剂的材料可以以低成本广泛获得。在所测试的电催化剂中，Cu _1.81 S @ WMCNT-600-OD在0.45 V的过电势下表现出对甲酸的高CO ₂选择性，并具有近20小时的高法拉第效率（82％）。进一步的研究表明，电解过程中形成的针状树状结构是改善CO ₂还原性能的可能来源。因此，这项工作为CO ₂ ER提供了一种低成本，丰富而有效的催化剂，并提供了一种改善电催化性能的简便途径。