Synthesis And Electrochemical Studies On Cu-based Trimetallic Nanoalloy Catalysts

As a traditional energy source,fossil fuels,due to its non-renewable nature and negative impact on the environment and human health,have partly hindered the sustainable development of the society.To solve this dilemma,the direct formic acid fuel cells(DFAFCs),as a member of clean and efficient fuel cells,have attracted much attention due to its higher current density.Compared with Pt-based catalysts,Pd-based catalysts are more suitable as catalysts for the DFAFCs because Pd-based catalysts have a propensity to promote the dehydrogenation reaction process during formic acid oxidation(FAO)and are less vulnerable to CO poisoning.However,it is hard for pure monometallic nanocatalysts to satisfy both high catalytic performance and high catalytic stability during catalytic oxidation.For this reason,alloy catalysts have been proposed to improve the drawback of single element materials on catalytic performance.In this work,we introduced the preparation of PdAgCu trimetallic alloy nanowires with rough surface structure by a facile successive reduction method.And then,the morphologies and compositions of the materials were qualitatively and quantitatively analyzed by TEM,HRTEM,XRD,EDS and other characterization methods.The results show that PdAgCu alloy NWs with the average diameter of 50 nm is a core-shell structure composed of copper nanowires in the "core" layer and PdAg and PdCu alloy nanoparticles coated on the "shell" layer.By electrochemical analysis of FAO,the electrochemical active area(ESCA)of PdAgCu alloy NWs and commercial Pd was 55.87 m2/g and 47.71 m2/g,respectively.After mass normalization,the FAO mass activity of PdAgCu alloy NWs at the peak was 2511 mA/mgpd,which was 5 times than that of commercial Pd(506 mA/mgpd).The specific activity of PdAgCu alloy NWs and commercial Pd was 4.49 mA/cm2 and 1.06 mA/cm2,respectively.The results prove that the catalytic performance of the FAO of trimetallic PdAgCu alloy NWs is significantly better than that of single metal commercial Pd.In this paper,PdAgCu trimetallic alloy nanotubes were successfully prepared by changing the reaction solvent and using the post-treatment,acetic acid(AA)leaching.Comparing the TEM before and after AA indicates that a tubular structure with a wall thickness of?2 to 5 nm is formed.Besides,the theory calculation of miscibility temperature was used to further demonstrate the reason why AgCu could not form the alloy phase in the trimetallic alloy nanomaterials.That is,the actual reaction temperature is much lower than the melting temperature of the AgCu alloy.Finally,electrochemical tests demonstrated that the FAO mass activity of the alloy nanotubes(4307 mA mgPd-1)was 3.3 times than that of the trimetallic alloy nanowires(1305 mA mgPpa-1),and 8.5 times than that of commercial Pd(506 mA mgPd-1).In conclusion,the successful preparation of PdAgCu trimetallic alloy nanotubes can not only reduce the amount of noble metal Pd,but also enhance the catalytic performance.