Study On Application Of Heteroatom Doped,Porous Carbon-based Metal-free Catalyst In The Reduction Of Carbon Dioxide

Electrocatalytic carbon dioxide reduction provides a new direction for resolving energy shortages and environmental problems.However,due to the high energy barrier of carbon dioxide reduction reaction,its electrochemical reduction reaction requires an efficient electrocatalyst to boost it.Carbon-based metal-free catalysts are promising in the field of electrocatalysis due to their excellent stability,easy-to-control structure,and excellent catalytic activity.However,carbon dioxide reduction catalysts with high selectivity,high activity,and good durability is a challenge.In this paper,several high-performance metal-free catalysts have been prepared by heteroatom doping method:1.We report a boron and nitrogen co-doped mesoporous carbon(denoted as BNMC)as low-cost metal-free catalyst for CO2RR,by pyrolysis of a precursor mixture of urea,dicyandiamide,glucose and boric acid using silica as templates.The pore structures and N,B codoping contents of the BNMC were tuned via changing pyrolysis temperature and template content.Among them,the catalyst prepared at 1000? exhibited the most excellent performance,and was able to efficiently reduce CO2 to CO with 95%Faraday efficiency under an overpotential of only 423 mV.At the same time,we compared the performance of the catalyst withiout boron doping and template,and confirmed that the boron and nitrogen element in the catalyst have a coordinated role for CO2 reduction,and the porous structure is the key to the catalyst's efficient reduction of carbon dioxide.2.We borrowed the conclusion of the first subject,and also used the hard template method,using thiocyanuric acid as the sulfur source,adjusting the feeding ratio,removing the template after carbon to prepare a series of nitrogen-like,sulfur co-doped three functions catalyst.The optimized catalyst NSMC-1000 can also efficiently reduce CO2 to CO with a Faraday efficiency of 93%under an overpotential of 423 mV.At the same time,the catalyst also has certain OER performance.In a 0.1 M KHCO3 solution saturated with CO2,only 1.75 V(VS RHE)is required to reach a current density of 10 mA/cm-2.Therefore,we applied NSMC 1000 to the carbon dioxide overall splitting test and used a potentiostat to drive the reaction.We found that the electrolytic cell can maintain a 90%Faraday efficiency to overall splitting carbon dioxide in a wide voltage range.The efficiency can be maintained at about 60%,achieving efficient decomposition of carbon dioxide.