Electrochemical conversion of CO₂ (CO₂RR) into high-value fuel is identified as one of the promising approaches to achieve carbon neutrality. The synthesis of high-efficiency CO₂ reduction electrocatalysts with high C₂:C₁ selectivity remains a field of intense interest. Previous studies have shown that the presence of Cu(I) is beneficial for the reduction of CO₂ into C₂ products. However, the stable presence of Cu(I) remains controversial, especially in the negative potential window. Here we report a simple and easily scalable catalyst precursor Cu₂(OH)₃Cl/C, which automatically forms in-situ chlorine-doped Cu/Cu₂O hetero-interface during electrocatalysis. The catalyst not only exhibits a Faradaic efficiency of 33.03% but also provides a long-term stability of Cu⁺, gaining a stable electrolysis of 11 h, with an ethylene/methane ratio over 50. The experimental results and mechanistic studies confirm that the presence of Cl⁻ inhibits the reduction of Cu⁺, inducing the formation of Cu⁰/Cu⁺, and reduces the reaction energy of the intermediate *CO dimerization, thereby facilitating the formation of C₂ products. This work provides a feasible way to synthesize copper ions with long-term and stable positive charge in CO₂RR and expands a new way to synthesize ethylene industrial products in the future.

Lithium-sulfur (Li-S) batteries have become one of the most promising next-generation battery systems due to their high energy density and low cost. However, the application of Li-S batteries still faces critical challenges, such as the low conductivities of S and Li₂S, shuttle effect of polysulfides and dendrite growth of Li, etc. The optimization of the electrolyte can ameliorate the electrolyte|electrode interphase, conveniently regulating the parasitic reaction and improving the performance of the resultant batteries. The functional additives in electrolytes provide chances to tune the interphase and even the redox mechanism to improve the performance of the batteries. In this review, we systematically summarize the latest progresses of additives for Li-S batteries. The additives are classified according to the category that lies on the protection of Li metal anode or the stabilization of S cathode. The functions of additives on the S cathode such as the inhibitions of dissolution and shuttle of the polysulfides, the redox mediators, and the activation of Lii₂S deposits are discussed in detail. Finally, the prospects of additives for Li-S batteries are supplied in brief. We hope that the review can provide a guidance in the design of electrolyte for high-performance Li-S batteries.