Multiple active site metal-based catalysts for C-N coupling reactions and the beyond

Electrochemical C-N coupling reactions have resonated in the scientific community for the ability of integrating carbon sources and nitrogen sources to generate valuable industrial organonitrogen compounds under mild conditions, regarded as sustainable and green alternatives to defossilize conventional industrial processes. However, the low Faradaic efficiency and poor selectivity of C-N coupling reactions, arisen from obscure understanding of the complex multi-step reactions and competitive side reactions, hinder their practical applications. This highlights the demand for advanced catalysts with defined active sites. Metal-based catalysts with multiple active sites are promising due to their versatile active sites and synergistic effects between each component. This review outlines the underlying mechanisms and advanced detection methodologies essential for rational catalyst design. It examines key studies on metal-based catalysts with various active sites (T-T (Transition-Transition), T-P (Transition-P block), and P-P (P block-P block) combinations) and diverse feedstocks for reductive C-N coupling reactions. Additionally, it explores structural and electrochemical engineering strategies for single active site catalysts, applicable to multi-site catalysts. The review also covers mechanisms and current works in oxidative reactions. Finally, it addresses challenges and opportunities in designing metal-based catalysts with multiple active sites for C-N coupling reactions, aiming to enhance understanding and drive research towards industrial-scale carbon and nitrogen fixation.