Laser Synthesized High Performance Palladium Nanoparticle Catalyst For Oxygen Reduction

As a green and efficient power generation technology,proton exchange membrane fuel cells have rich application prospects.One of the core problems that restrict their development is that the over-potential of the oxygen reduction reaction（ORR）as the cathode reaction of the battery is too high,and the kinetics slow.Since the current fuel cell working environment is mostly strong acid conditions,it is particularly important to select a suitable acidic ORR reaction catalyst.At present,the common electrode material is rare precious metal platinum（Pt）,and its reserves and prices seriously restrict the wider application of fuel cells.Therefore,the current research focus is on how to improve the catalytic performance of other acid-resistant metals.The electron cloud density of the material is directly related to the strength of the oxygen bond energy,so it will affect the difficulty of the formation of intermediate products in the ORR reaction process.Therefore,by creating lattice strain and affecting the electron cloud density,it is possible to obtain a high performance catalyst.Therefore,palladium（Pd）was selected as the research object,and the lattice strain was created by laser liquid phase ablation method to regulate its adsorption of oxygen intermediates and ORR catalytic performance.The specific research results and innovations are as follows:（1）Pd nanoparticles with different internal lattice strains were obtained by laser liquid phase ablation method by adjusting laser parameters and solute concentrations.The method is simple and effective to obtain Pd nanoparticles with different lattice strain degrees,and overcomes the problem that the conventional method is difficult to obtain grain boundaries in the nanoparticles.（2）Analysis of the sample using XRD and XAS revealed that the lattice strain created by the laser resulted in lattice compression of the Pd nanoparticles with an average compression of about 3%.Comparing the prepared OR-performance of Pd nanoparticles with lattice strain,Pd nanoparticles with lattice strain after annealing,and commercial Pd/C,indicating that the compressed lattice can improve Pd in acidic and alkaline test conditions.The ability to catalyze ORR.（3）It is found through calculation that the compressive strain of Pd nanoparticles weakens the adsorption of all intermediates,especially the adsorption of O^*,so the energy barriers for the formation of OH^* and H₂O are significantly reduced,resulting in better ORR performance.The Pd nanoparticles prepared under 0.01 M NaCl have a half-wave potential of 0.78 V（vs.RHE）under acidic test conditions,comparable to Pt electrodes（0.79 V vs.RHE）,and exhibit better stability than Pt.Sexual and methanol resistant,and also exhibited good catalytic properties under alkaline test conditions.