Study On The Catalytic Effect Of Metal Sulfide Modified Electrode On CO₂ Electroreduction Reaction

CO₂ is not only the main gas component causing global warming,but also a potential carbon resource.Using renewable electric-energy for CO₂ reduction into CO,and then synthesize Value-added products is an important technical approach to realize CO₂ resource utilization.However,the lack of high-performance electrode materials limits the industrial application of CO₂ electroreduction technology.Aims at this problem,we have fabricated of ZnS/Zn and MoS₂ electrodes using metal surface sulfuration technology,and studied the electro-reduction mechanism of CO₂ on the above two metal sulfide modified electrodes,and finlly designed a multi-chamber diaphragm electrolysis cell system for CO₂ electro-reduction into CO,the main research contents and conclusions are as follows:?1?Fabrication of ZnS/Zn modified electrode using solid-liquid two-phase sulfuration method for CO₂ reduction into CO in in propylene carbonate/tetrabuty-lammonium perchlorate organic electrolyte,the results show that:Faraday efficiency of CO generation reached 94.5%,current density reached 14 mA/cm²,and overpotential decreased.Long period electrolysis experiment shows that the modified electrode has no attenuation.Through SEM,EDX,XRD,XPS and other detection means,it was found that the structure of ZnS/Zn modified electrode consists of three layers,the upper layer is ZnS and the base is Zn.There is a transition layer in the middle,which makes the ZnS of the surface layer firmly adhere to the base and not easy to peel off.?2?Fabrication of MoS₂ electrode using low temperature ion-sulfurizing technique,and then,in propylene carbonate/tetrabuty-lammonium perchlorate organic electrolyte,the electroreduction reaction of CO₂ on the MoS₂ modified electrode was studied.The results showed that the current density of CO generated reached 20mA/cm²,and the current efficiency reached 90%,and the electrode was not poisoned.The structure of modified electrode includes three layers,the upper layer is MoS₂,the base is Mo,and there is a transition layer in the middle.Compared with ZnS/Zn modified electrode,MoS₂ modified electrode has higher catalytic activity and better application prospect.?3?In order to promote the practical application of CO₂ electroreduction technology,this paper designed and built a multi-chamber diaphragm electrolytic cell system,and carried out an expanded laboratory experiment.Electrolytic cell system includes a multi-chamber diaphragm electrolytic cell,gas absorption device and electrolyte circulation device,among them,the electrolytic cell comprises cathode chamber and anode chamber,which was separated by porous silicone paper membrane,cathode chamber was injected propylene carbonate/tetrabuty-lammonium perchlorate organic electrolyte that containing carbon dioxide,anode chamber was injected the dilute sulphuric acid solution,the cathode was Ag electrodes,anode was coated titanium electrode.The experiment results indicated that CO₂ can be continuously and stably reduced to CO in the multi-chamber diaphragm electrolysis cell system,and the current density of CO generation does not decline in the long cycle electrolysis process.So,the preliminary expanded experiment in this laboratory has important scientific research value and industrial application prospect.