Nanocube crystals of bimetallic Ag-Cu-Melamine molecular complexes have been originally developed as effective electrocatalysts for the CO₂ selective reduction to multicarbon products, particularly ethylene and ethanol. The bimetallic complex, containing 10 wt.% Ag demonstrates the highest performance in electro-reduction of CO₂ in both H-type and flow cells. It achieves a Faradaic efficiency of 70 % for C2 products, with 40 % attributed to ethanol and the remaining to ethylene. These results are obtained at a cathode potential of -1.0 V vs reversible hydrogen electrode (RHE) with a total current density of -50 mA·cm^-2 in the flow cell, five times higher current densities than the current densities in the H-Cell. Without Ag in the complex, only C1 products (CO and formic acid) are detected. The use of the flow cell, in addition to higher current densities, enhances C2 formation, especially ethylene, which is absent in H-type cell experiments. These novel electrocatalysts also exhibit stable performances and provide mechanistic indications of the roles of Ag and tandem cooperation with Cu.

Nowadays, extensive efforts have been devoted to the fabrication and design of metalbased catalysts with high activity, selectivity, and stability. Theoretical and experimental investigations have empowered the construction of a variety of techniques to tune the catalytic efficiency of catalysts by monitoring their size, morphology, composition, and crystal structure. Multimetal catalysts (MMCs) provide a revolutionary synergistic effect between metals, which is a promising strategy to tune and enhance the catalysts’ productivity and product selectivity. The purpose of this article is to familiarize readers with the most uptodate information regarding the synthesis and classification of MMCs. The key roles of MMCs electrocatalysts in a variety of applications such as CO₂ conversion via electrochemical CO₂ reduction reaction (ECO₂RR), H₂ evolution reaction (HER), O₂ evolution reaction (OER), O₂ reduction reaction (ORR), N₂ reduction reaction (NRR), methanol oxidation reaction (MOR), ethanol oxidation reaction (EOR), formic acid oxidation reaction (FAOR), and urea oxidation reaction (UOR) are summarized. This review also addressed the challenges and prospects for multimetallic catalyst design, characterization, and applications. This review article will provide a clear roadmap for the research and progress of multimetallic catalysts for electrocatalytic applications.