Controllable Construction Of Non-noble Metal Dual Sites Synergistic Catalytic CO₂ Electroreduction

The energy crisis and environmental pollution have inspired the rapid development of sustainable energy.The electrochemical reduction reaction of carbon dioxide（CO₂RR）is one of the most promising strategies for storing intermittent solar and wind energy in carbon-based fuels and reducing greenhouse gas emissions.Electrochemical hydrogen pump reactor（EHPR）with a circulating buffer layer has been applied to conduct the electrocatalytic CO₂RR in this work.In EHPR,mass transfer resistance could be reduced due to the direct CO₂ feeding to the cathodic active sites and the extremely thin buffer layer.However,EHPRs reported in the literature mostly use nano-metal catalysts（such as Sn powder）,which suffers from low selectivity,difficulty in product separation,and poor long-term cycle stability.Therefore,the successful realization of energy-saving CO₂RR processes requires catalysts with both high selectivity and low overpotential to overcome the thermodynamic and kinetic sluggishness of CO₂RR and avoid competition from the hydrogen evolution reaction（HER）.Here in this work,the manipulation of the local structure of the catalyst,together with the fine tuning of electronic densities are integrated to upgrade the catalytic behavior.First,a host-guest synthesis strategy was used to design and prepare a highly exposed Ni/Co atom pair catalyst anchored on a three-dimensional（3D）porous carbon matrix.The porous structure of the carbon layer has a richer specific surface area for the purpose of providing more reactive areas and promoting directional charge and mass transfer.And the atomically dispersed active sites facilitate the transportation of reaction materials and accelerate the adsorption and transformation of reaction intermediates.The catalyst exhibits high selectivity with CO Faradaic efficiency above 90%over a wide potential range from-0.6 to-1.1 V（vs.RHE）,and robust durability,retaining 94%of its initial selectivity after 40 hours of electrolysis.On this basis,an in-situ coating method is proposed to precisely control the spatial distance of the metal dimer to efficiently synthesize Fe-Cu heteronuclear diatomic catalyst to further improve the catalytic performance.The diatomic catalyst effectively integrates the advantages of homogeneous and heterogeneous catalysts and maximizes the synergistic function based on different molecules and their interfaces.At the same time,the Fe-Cu-N heterogeneous interface promotes the redistribution of electrons to show more electronic states and increase the conductivity of the catalyst.The local structure strategy and the electronic interaction synergistic effect simultaneously improve the selectivity and current density of CO generated by reaction,and show excellent CO₂ electrocatalytic reduction performance.The obtained Fe/Cu-N-C diatomic catalyst exhibits an excellent CO Faradaic efficiency（>95%over a wide potential range of-0.4 to-1.1 V vs.RHE,>99%at-0.8 V vs.RHE）,and a low overpotential（50 m V vs.RHE）,thus outperforming most reported atomically dispersed catalysts.Finally,relying on the first principles to explore the mechanism of diatomic catalysts significantly improving the performance of CO₂ electrocatalytic hydrogenation at the theoretical level.The extended X-ray absorption fine structure measurement（EXAFS）clarifies the special structure of the active center（N₄Fe-Cu N₃）;the density functional theory calculation（DFT）further indicate that the synergistic effect between Fe-Cu diatoms causes rapid charge transfer and effectively adjusts the position of the d-band center,which reduces the energy barriers for*COOH formation and*CO desorption.