Se/P Coupling B,N Co-doped Carbon Materials For Tunable Syngas Production

Syngas（a mixture of H₂ and CO）is a key feedstock for industrial synthetic fuels and chemicals,and its conventional production method is based on reforming non-renewable fossil fuels,aggravating the energy crisis.The production of syngas through the CO₂ electroreduction reaction（CO₂RR）process driven by renewable electricity will not only help reduce the amount of greenhouse gases and alleviate the energy crisis,but more importantly,it can adjust the composition of the syngas to meet different industrial demand.As a key factor affecting the production efficiency and composition of syngas in the CO₂RR process,it is of great significance to explore efficient and robust catalytic materials that can achieve tunable syngas production.In recent years,carbon catalytic materials have been favored by researchers due to their wide range of raw materials,high temperature resistance,acid and alkali resistance,anti-poisoning,and environmental friendliness.Moreover,the introduction of heteroatoms with different electronegativity into the carbon material can significantly improve its catalytic activity.Among them,when B and N atoms are doped into carbon materials,adjacent B and N can use their synergy effect to break the electrical neutrality of sp² C to promote charge transfer efficiency and catalytic activity,this has been recognized by researchers.However,B,N co-doped carbon still has room for further improvement as a catalytic material.Trying to introduce additional heteroatoms to couple with B,N co-doping can achieve a more ideal enhanced catalytic performance.In this paper,firstly,the B and N co-doped nano-layered carbon electrocatalytic materials were prepared by the pyrolysis of molten salt method.Subsequently,Se and P atoms were introduced to couple with B and N co-doping respectively,and Se coupled B,N co-doped porous carbon and P coupled B,N co-doped carbon electrocatalytic materials were obtained.The three electrocatalytic materials prepared in this paper have good catalytic performance when applied to the production of tunable syngas.The specific research content is as follows:Part I Study on the preparation of tunable syngas from B,N co-doped nano-layered carbonIn this part,using melamine as the nitrogen source,sodium tetraphenylborate as the boron source,sucrose as the carbon source,and sodium chloride as the template,the B,N co-doped nano-layered carbon electrocatalytic materials were prepared by the pyrolytic molten salt method.Further study was made on its catalytic performance in the preparation of tunable syngas.The electrochemical test results show that when the heat treatment temperature is 900℃and the ratio of sodium tetraphenylborate to melamine is 1:200,it has the best catalytic performance:FE_CO and FE_H2 reach the optimal values of 83.5%and 16.5%at-0.6 V.At the same time,the catalytic material has good long-term stability,and the Faradaic efficiency and current density remain basically stable during the 10-hour electrolysis process.More importantly,when preparing syngas with CO₂RR,changing the applied potential can adjust the H₂/CO ratio of the syngas within the range of 0.2 to 3.2.Part II Study on the preparation of tunable synthesis gas by Se coupling B,N co-doped porous carbonSe has the characteristics of large atomic size,high polarizability and abundant d electrons,and it is a good choice for enhancing the electrical transport performance of carbon skeletons.Therefore,this part uses cheap selenium powder,sodium tetraphenylborate,chitosan and ammonium chloride as raw materials to prepare Se coupled with B,N co-doped porous carbon electrocatalytic materials through simple pyrolysis and use them to prepare tunable syngas.Among them,the electrocatalytic material obtained at a heat treatment temperature of 1100°C showed the optimal catalytic activity:FE_CO and FE_H2 reached 95.2%and 4.8%at-0.6 V,respectively.At the same time,the catalytic material also showed good long-term stability:after 10hours of electrolysis,the Faraday efficiency and current density remained at 97.6%and 84.7%of the initial value,respectively.Part III P coupling B,N co-doped carbon to prepare tunable syngasIn addition to its larger atom size and valence bond,P also has excellent electron donating ability,which can significantly increase the electrical conductivity and enhance its CO₂RR catalytic activity.Therefore,in this section,tetraphenylboron tetraphenylphosphorus(C₄₈H₄₀BP)is used as a source of boron and phosphorus instead of sodium tetraphenylborate,and a P-coupled B,N co-doped carbon electrocatalytic material is prepared and applied to prepare tunable syngas.By studying the effect of heat treatment temperature and the molar ratio of C₄₈H₄₀BP to melamine on the catalytic performance,it is found that the catalytic material prepared at 1000℃and 1:200 has the best catalytic performance:FE_CO and FE_H2 are 81.8%and 18.2%at-0.5 V,respectively.In addition,after 10 hours of electrolysis,the Faraday efficiency of the catalytic material is still 95.0%of the original,and it has good long-term stability.At the same time,the H₂/CO ratio in the product can be simply adjusted within the range of 0.2 to 6.8.