Preparation And Electrocatalytic Performance Of Layered Perovskite Oxide GdBaCo₂O_5+δ

Because of its environment-friendly methods for producing hydrogen and oxygen,electrolytic water has recently caught the interest of academics worldwide.It is considering the high cost of precious metals and the resource reserves being small.Therefore,it is necessary to develop a non-precious metal electrocatalyst with low cost,high activity,and high stability.Perovskites have received widespread attention due to their rich content,low-cost elements,and high electrical and catalytic activity,which is accessible to mass production.In this paper,a B-site cationic doped perovskite catalyst based on GdBaCo₂O_5+δwas prepared.Considering that carbon-based source dramatically influences the ORR activity of perovskite,the surface of perovskite was modified with MOF to improve its stability and ORR performance.（1）GdBaCo_2-xFe_xO_5+δ（X=0,0.1,0.2,0.3,0.4,0.5）perovskite catalyst was synthesized by the Pechini method.GdBaCo_1.6Fe_0.4O_5+δ（GBCF40）showed the best OER activity among the synthesized catalysts.GBCF40 has an overpotential of 298m V at 10 m A cm^-2,and its smaller Tafel slope(79.19 m V dec^-1)implies rapid OER dynamics.X-ray photoelectron spectroscopy（XPS）results show that the average valence state of Co ions in GBCF40 is significantly lower than before doping,and the composition of lattice oxygen is reduced,indicating that the oxygen vacancy is increased,resulting in excellent electrocatalytic OER performance.（2）Since MOF contains a large amount of porous carbon after carbonization,this paper uses MOF ZIF-67 to perform a hybrid on the surface of perovskite GBCF40,which has the highest OER activity,in an attempt to introduce active carbon-based sources to further improve its ORR performance and stability further.The prepared GBCF40@Co-C benefits from the synergistic action of perovskite GBCF40 and surface porous conductive active carbon-based source.At 1.56 V（RHE）high potential in an alkaline environment,the average current density is better than perovskite GBCF40 and precious metal Ru O₂.The ORR half-wave potential of GdBaCo_2-xFe_xO_5+δ（X=0.4）@Co-Cabon（GBCF40@Co-C）is 0.850 V,which is better than the half-wave potential of 20wt%Pt/C（0.838 V）.Under the 5000 CV cycle,the half-wave potential only attenuates 5 m V,which is better than the half-wave potential attenuation of 20wt%Pt/C under the same conditions.Its small Tafel slope(61.83 m V dec^-1)indicating fast ORR dynamics.