High-Performance Inorganic Electrocatalysts For Carbon Dioxide Reduction Reaction

With the rapid development of the social economy,the contradiction between the use of fossil fuels and environmental protection has intensified.Therefore,the development of a sustainable new energy system has become an important way to realize the transformation of the future energy structure.Among many new energy storage and conversion technologies,electrocatalytic CO2 reduction reaction has attracted widespread attention due to its mild reaction conditions and large economic benefits.However,it's very challenging to take the reaction into practical applications regarding its poor product selectivity and low energy conversion efficiency.Therefore,it is extremely urgent to develop catalysts with cheap price and high activity as well as"particularly high selectivity for electrochemical CO2 reduction.This paper introduces the design ideas of three electrocatalysts and their further catalytic performance in CO2 reduction reaction.The details are as follows:We developed a facile two-step method to prepare SnO2 nanoclusters by using dopamine as the carbon source.Dopamine was first polymerized together with SnO32-in its alkaline solution to form Sn-PDA composite.Subsequently,the precursor was calcined at a milder temperature to form SnO2 nanocrystals with N-doped carbonaceous support.The coated carbonaceous support could suppress the agglomeration of SnO2 nanocrystals and preserve their surface sites for sustained CO2 reduction reaction.When evaluating the catalyst in 0.5 M NaHCO3,SnO2-NCs exhibited the peak formate Faradaic efficiency of-73%and a current density of 16.3 mA/cm2 at-0.92 V vs.RHE,which was about 40-230 mV earlier than literature results.Moreover,the material could maintain its catalytic performance for more than 20 hours.We prepared the atomic-thick 2D Bi2O2CO3 nanosheets via a facile solvothermal reaction and further obtained mpBi nanosheets by cathodic transformation of the precursor.The final product maintained the unique 2D mesoporous nanosheet morphology with enlarged surface areas and abundant under-coordinated Bi sites for CO2 reduction.When employed as the electrocatalyst for CO2 reduction reaction in 0.5 M NaHCO3,mpBi showed excellent catalytic activity towards the conversion of CO2 to formate.It enabled a large carhodic current density of 18 mA/cm2 and excellent selectivity(>90%)over a broad potential window.The performance was superior to popular Sn-based materials as well as most other formate-producing electrocatalysts.Finally,we coupled mpBi catalyst with commercial Ir/C catalyst in a full cell,and achieved battery-driven or solar-driven splitting of CO2 into formate and oxygen at high energy conversion efficiency.We developed a green,robust and efficient method for the preparation of monodisperse hollow polydopamine with sodium citrate as the templates.We could obtain N-doped carbon material by directly pyrolyzing hollow polydopamine under NH3,We could also obtain Ni and N-doped carbon material by immersing precursor in solution to introduce transition metal Ni.Both materials maintained the hollow carbon sphere structure with enlarged surface area for CO2 reduction reaction.Compared with N-HCS catalyst,Ni-N-HCS catalyst exhibited dramatically higher selectivity and activity.Ni-N-HCS catalyst revealed a cathodic current density of 20 mA/cm2 and excellent selectivity(>80%)over a broad potential window.Additionally,it showed excellent stability for at least 12 hours and the structure was survived after the reaction.