Experimental study of electrocatalytic CO2 reduction by nano-SnO2 based on stacked electrolytic reactor

WEI Shuzhou; TAN Shuting; XIONG Zhuo; XU Zuwei; ZHAO Yongchun; ZHANG Junying

doi:10.13226/j.issn.1006-6772.LC23112001

Abstract：The electrocatalytic reduction of carbon dioxide(CO2)using new energy and electrical energy can convert CO2 into value-add-ed chemicals while reducing carbon emissions,which has broad application prospects.Among the various reduction products,formic acid(HCOOH)is easy to store and transport,with a high storage density of hydrogen.Tin oxide(SnO2)electrocatalytic materials are low-cost and less toxic,while SnO2 is highly selective for HCOOH when used for electrocatalytic reduction of CO2.In the industrialization of electrocatalytic reduction,a reasonable electrolytic reactor structure is of great significance.To explore a more reasonable electrolytic re-actor structure,this paper proposes a homemade multilayer stacked electrolytic reactor,in which SnO2 nanoparticles prepared by flame spray pyrolysis method are used as electrocatalysts for electrocatalytic reduction of CO2.The effects of parameters such as cathode-anode spacing,electrolyte flow rate,electrolyte concentration and the number of electrode stacks on the electrocatalytic performance of the elec-trolytic cell were investigated.The experimental results show that:the closer the cathode-anode distance is,the lower the electrical energy loss is,and the catalyst has better catalytic performance;the flow rate of the electrolyte has no significant effect on the reduction perform-ance of the catalyst,but when the flow rate is too fast,the current density of the reaction produces a more drastic fluctuation.When the electrolyte concentration was less than 1 mol/L,the selectivity of the catalyst for HCOOH increased with the increase of the electro-lyte concentration,whereas the selectivity of the catalyst for each product stabilized at the electrolyte concentration of more than 1 mol/L.The current density decreased slightly when the electrodes were placed in stacks,but the overall Faraday efficiency and the Faraday effi-ciency of HCOOH both increased,and the hydrogen precipitation reaction was suppressed more significantly.The charge transfer resistance and diffusion resistance were reduced when using a stack electrolytic reactor.The optimum Faraday efficiency for HCOOH of SnO2 under stack conditions reaches 37.53％and the total Faraday efficiency reaches 75.83％with the cathode-anode spacing of 10 mm,the applied potential of-1.2 V vs.RHE,and the KHCO3 concentration of 1 mol/L.The results indicate that the catalytic per-formance of the catalyst and the selectivity of the target products can be enhanced by using a stacked electrolytic reactor.