Design, Preparation And Performance Study Of Direct Formic Acid Fuel Cell Catalyst

Direct formic acid fuel cells(DFAFCs)have the advantages of rapid starting speed,low operation temperature,high energy density,convenient fuel storage and transportation,exhibiting great potential for development and application in power sources and electric vehicles.Currently,Pd is the commonly studied catalyst for anodic formic acid oxidation reaction and Pt is also the traditional catalyst for cathodic oxygen reduction reaction.Nevertheless,the catalysts on both anode and cathode suffer from limited activity and poor stability.Therefore,it is of important to explore new types of electrocatalysts for DFAFCs with favorable activity and stability.Fundamentally,the catalytic performance of catalysts is mainly determined by the geometric and electronic structures.In recent years,regulating the electronic structure of noble metals and conducting morphology control on the nano scale have attracted enormous attention.In this paper,layered Pd Mn nanosheet assemblies(Pd Mn NBs),Mo-doped Pt nanocluster assemblies,and Pt Ni Co Mn W high-entropy alloy nanocubes were prepared,and their geometric and electronic structures,electrocatalytic properties,and corresponding catalytic mechanism were analyzed and studied.Its main contents are as follows:(1)We reported the synthesis of Pd Mn nanosheet assembled nanobuds(Pd Mn NBs)with a 3D hierarchical structure via a polymeric surfactant-free strategy.Toward FOR,the prepared Pd Mn NBs deliver 4.2 times greater mass activity and also highly enhanced durability than the control sample Com Pd-C.The contribution of strain effect can be essentially eliminated since Pd and Mn have similar atomic radius.Thus,we speculated that catalytic enhancement mechanism should be attributed to the generated ligand effect.(2)A unique Mo doped Pt clusters-assembled coral-like nanostructure(Mo-Pt CA)was prepared by using a surfactant-free wet-chemistry approach,exhibiting high catalytic activity and stability toward ORR.The catalyst possesses a robust porous Modoped skeleton structure associated with high Pt utilization accomplishes a highly enhanced mass and specific activities as well as stability with the Commercial Pt/C(Com Pt/C)catalysts.In terms of our experimental results and density functional theory(DFT)calculations,we propose that the origin of improvement in activity is mainly ascribed to a modulated unique electronic structure of Pt,which weakens adsorption energy of the produced O* intermediate by stretched Pt-O bond length up to 2.110 (?)for easier dissociation and consequently offers high ORR activity.Importantly,although the low adsorption energy of O*(ΔEO*)induced by the stretched Pt-O bond length leading to high ORR activity has been reported,we reveal that the Pt-O bond length of2.110 (?) is the highest value among reported Pt-based structures and Mo-Pt CA in this work as far as we know.(3)We synthesized Pt Ni Co Mn W-based high-entropy alloy nanocubes by a universal one-step solvothermal method,which enriched the high entropy alloy nanomorphology.It provides a potential ORR catalyst with effective reduction of Pt load of precious metals.