Rational Design And Mechanism Investigation Of Copper Based CO₂ Electroreduction Catalysts

The industrial structure formed since the industrial revolution is greatly dependent on fossil energy,and the consumption of fossil energy has caused a sharp rise of carbon dioxide in the atmosphere,which poses a great threat to the earth's ecological environment and the sustainable development of human society.We urgently need to adjust the industrial structure and develop the low-carbon economy vigorously to solve this problem.At the same time,the artificial fixation of carbon dioxide in the atmosphere is also an important way to reduce its concentration.Using electrochemical method to reduce carbon dioxide can not only reduce the concentration of carbon dioxide,but also obtain other high value-added chemicals.In recent years,many researchers have carried out comprehensive and systematic research on the electrocatalytic reduction of carbon dioxide,and a series of excellent achievements have sprung up.Many efficient catalyst systems have attracted people's attention,among which copper is the most shining pearl.Compared with other catalysts,copper based materials can convert carbon dioxide into m?Lti carbon products and hydrocarbons,which has a wide application prospect.In this paper,we design and process copper based materials from various angles.Evaluated the performance of these materials in the electrocatalytic carbon dioxide reduction reaction,a series of scientific point about catalyst structure and reaction mechanism have been discussed deeply.The res?Lts we have achieved are as follows:(1)The structure evolution and surface reconstruction of copper based catalysts are common phenomena in the process of electrocatalysis.We chose Cu2-xS as original material to investigate the performance of the electrocatalytic carbon dioxide reduction.During a long-time test,the Faraday efficiency ethylene increased from 25.3%to 68.8%.Based on the res?Lts of in situ tests,we found the relationship between the high-index surface ratio of polycrystalline copper nanoparticles and the Faraday efficiency of ethylene.The intermediate of*COCHO was detected by in situ Raman test.This work provides sufficient evidence for us to understand the structure evolution and structure-activity relationship of copper based catalysts.(2)MOFs materials provide us a wide space to study a lots of chemical reactions.Cu-BTC was chosen as our research object.The structure of Cu-BTC can be modified by adding benzimidazole properly in the synthesis process.The N-doped Cu-BTC was calcined properly,and the Cu-C-N porous composite structure was obtained.The catalyst showed excellent performance in electrocatalysis of carbon dioxide to ethylene.This work provides a rich perspective for us to design electrocatalytic carbon dioxide reduction catalysts.(3)Because of the large specific surface area,rich active sites and controllable mass transfer process and other advantages,hollow structure catalyst is suit for electrocatalytic carbon dioxide reduction reaction.Doping other metal or non-metal elements into the Cu lattice can reg?Late its electronic structure and surface structure.CuIn alloy nanocrystals were obtained.By adding s?Lfur source into the system,CuIn alloy nanocrystals were transformed into CuInS2 catalyst with hollow structure.The CuInS2 hollow nanostructures exhibit excellent catalytic activity for electrochemical reduction of CO2 with partic?Lar high selectivity,achieving high faradaic efficiency for HCOOH of 72.8%at-0.7 V.To elucidate the mechanisms,we employ operando electrochemical Raman spectroscopy to examine the CO2 reduction process.This work provides new insights into the design of hollow nanostructures toward electrocatalytic CO2 conversion and offers us an effective and reliable way for real-time investigation of electrochemical CO2 reduction reaction processes.