Highly Selective Tandem Electroreduction of CO₂ to Ethylene over Atomically Isolated Nickel–Nitrogen Site/Copper Nanoparticle Catalysts

Herein, an effective tandem catalysis strategy is developed to improve the selectivity of the CO₂ RR towards C₂ H₄ by multiple distinct catalytic sites in local vicinity. An earth-abundant elements-based tandem electrocatalyst PTF(Ni)/Cu is constructed by uniformly dispersing Cu nanoparticles (NPs) on the porphyrinic triazine framework anchored with atomically isolated nickel-nitrogen sites (PTF(Ni)) for the enhanced CO₂ RR to produce C₂ H₄ . The Faradaic efficiency of C₂ H₄ reaches 57.3 % at -1.1 V versus the reversible hydrogen electrode (RHE), which is about 6 times higher than the non-tandem catalyst PTF/Cu, which produces CH₄ as the major carbon product. The operando infrared spectroscopy and theoretic density functional theory (DFT) calculations reveal that the local high concentration of CO generated by PTF(Ni) sites can facilitate the C-C coupling to form C₂ H₄ on the nearby Cu NP sites. The work offers an effective avenue to design electrocatalysts for the highly selective CO₂ RR to produce multicarbon products via a tandem route.