Design Of Catalytic System For Electrocatalytic Carbon Dioxide Reduction And Targeted Oxidation Of 5-hydroxymethyl Furfural

The utilization of green energy to achieve the conversion of CO2 generated from fossil resources and the resourceful utilization of renewable biomass resources is of great importance.The oxygen produced by the corresponding anode in CO2 electroreduction reaction(CO2RR)is a low-value byproduct,while 5-hydroxymethylfurfural(HMF)derived from renewable biomass can be oxidized into a higher value 2,5-furandicarboxylic acid(FDCA).In this work,a cathodic CO2 reduction(e CO2RR)and anodic oxidation of HMF(HMFOR)system were established using a bifunctional ultrathin nanoflake catalyst.Firstly,CO2 was electrocatalytically reduced at the cathode,and the catalyst formed a Cu/Cu2 O heterojunction by self-evolution during the electrocatalytic process.The reduction product C2H4 had a high Faraday efficiency of70.2%,and the Faraday efficiency and current density did not change after 45 h of stable electrolysis in an H-tank with neutral KCl electrolyte.Secondly,anodic electrooxidation of HMF as FDCA and the transformation of Cu(OH)2 nanorods loaded on copper foam(Cu(OH)2-NR@Cu)to Cu O nanoflakes(Cu O-NF@Cu)resulted in a gradual increase in the number of exposed Cu atoms per unit plane.HMF was electrochemically oxidized to FDCA with high activity and stability,and the Faradaic efficiency could reach 99.3%.Finally,an electrocatalytic coupling was carried out in a flow cell electrolysis cell,and the cathode obtained a C2H4 Faradaic efficiency of 74.5% and the anode obtained a FDCA Faradaic efficiency of 95.6% at a cell voltage of 2.75 V.More importantly,this work achieved the coupling reaction on a low-cost bifunctional non-noble metal electrode,which paves the way for the resourceful utilization of CO2 generated from fossil resources and renewable biomass resources in the future.single-atom alloy catalyst is widely used in liquid phase aerobic oxidation reactions.However,how Pd and Au atoms in Au Pd single-atom alloy catalyst worked synergistically and whether single atom isolated Pd or Au atoms are superior than their nanoparticle or nanoalloy counterparts in liquid phase are less investigated.Here,with nitrogen doped carbon as supporting material,Pd,Au dual single-atom-catalysts(SACs)and Au Pd single-atom alloy catalyst are prepared and compared in catalyzed aerobic oxidation of 5-hydroxymethylfurfural(HMF).The results show that Pd,Au dual SACs had much worse catalytic activity for the transformation of HMF into 2,5-furandicarboxylic acid(FDCA).Remarkably,Au Pd single-atom alloy catalyst gives excellent catalytic activity.DFT calculations demonstrate that the charge state of Pd sites can be varied obviously with the changing of surrounding coordination atoms.Pd dimer in Au(111)was shown to be the most favorable active sites.This work emphasizes the importance of coordination atoms type,number in catalyst synthesis on their catalytic activity and opens an avenue in future rational design of Pd and Au based SACs.Compared with thermal catalysis,electrocatalytic 5-hydroxymethylfurfural is characterized by mild reaction conditions,low energy consumption and high atomic economy advantages.Ni2Fe(CN)6 catalyst was prepared for the constant potential oxidation of HMF at 1.57 V.Both the yield and FE of FDCA were maintained above 99%.