Preparation Of Pd-Ni Composite Catalyst With Nickel Trioxide As Nickel Source And Its Catalytic Performance For Electrooxidation Of Ethanol

With the growing problem of environmental degradation and fossil energy shortage,direct ethanol fuel cells（DEFCs）have attracted much attention due to their compliance with the standards of green chemistry and as a energy conversion device.However,the high cost of anode noble metal electrocatalysts used in the ethanol oxidation reaction（EOR）process has stalled the development of DEFCs.In order to improve the status quo,the researchers found that the introduction of metal nickel would promote the adsorption of OH^-on the catalyst.The previous work of this paper is to prepare Pd-Ni composite catalyst with Ni₂O₃,Pd O·H₂O and glucose as the main raw materials,and modify it on this basis.Compared with the preparation of other Pd-Ni catalysts,Ni₂O₃and Pd O·H₂O are used as nickel source and palladium source respectively in this work,and no other impurities are introduced into the target catalyst.This is the biggest feature of this work compared with other Pd-Ni catalysts previously reported.The specific experimental arrangement is as follows:1.Preparation of Pd-Ni composite catalyst with Ni₂O₃as nickel source.First,the precursor containing Ni O and carbon materials was prepared by hydrothermal method assisted air calcination with different nickel sources（Ni₂O₃,Ni Cl₂,Ni（CH₃COO）₂）and glucose as starting materials,and then the precursor was hydrothermally reacted with Pd O·H₂O to prepare the final catalyst.SEM images show that different nickel sources and Ni₂O₃with different quality have great influence on particle size and surface morphology.According to XRD and XPS measurements,Ni O and metal Pd are the main components of the catalyst except carbon materials.The effects of different nickel sources and different quality Ni₂O₃on the catalytic performance of the catalyst were investigated.The catalyst with nickel source of 0.05 g Ni₂O₃showed the highest EOR electrocatalytic activity and excellent resistance.In the CV test,the forward peak current density is approximately 32.43 m A cm^-2.In the CA test,the EOR polarization current density measured at-0.3 V for 7200 s remains at the level of 2.68 m A cm^-2.This shows that a new Ni O/C precursor has been synthesized,and a new high-performance Pd-Ni composite catalyst for EOR has been prepared.2.Preparation of Pd-Ni composite catalyst under different nitrogen source.Two methods were used to prepare Pd-Ni composite catalysts under different nitrogen sources（ammonium fluoride,urea,ammonium carbonate）.First,different nitrogen sources were reacted with Ni₂O₃and glucose respectively,and the precursor was prepared by hydrothermal method assisted air calcination method,and then hydrothermal reaction with Pd O·H₂O was carried out to obtain the catalyst.Second,the above substances are directly hydrothermal to obtain carbon ball support,and the support and Pd O·H₂O are hydrothermal to obtain catalyst.SEM and TEM images show that different nitrogen sources and preparation methods have great effects on particle size and surface morphology.XRD and XPS results showed that carbon materials,Ni O and metal Pd were the main components of the catalysts.The effects of different nitrogen sources and different preparation methods on the catalytic performance of the obtained catalyst were investigated.The catalyst prepared by direct hydrothermal method with ammonium carbonate as nitrogen source showed the highest EOR electrocatalytic activity and resistance.3.Preparation of Pd-Ni composite catalyst in the presence of ionic liquids.Ni₂O₃,glucose and[BMIM]OTf ionic liquid were used as raw materials to prepare the precursor by hydrothermal method assisted air calcination,and then the precursor was hydrothermally reacted with Pd O·H₂O to obtain the catalyst.SEM images showed that the particle size and surface morphology of the obtained catalyst were affected by different volume ionic liquids and different mass precursors.The effects of ionic liquids with different volumes and precursors with different mass on the electrocatalytic properties of the obtained catalysts were investigated.The catalyst prepared from the precursor（hydrothermal reaction of 15 mg precursor and 15 mg Pd O·H₂O）when the ionic liquid was 0.3 m L showed the highest EOR electrocatalytic activity and excellent resistance.In the CV test,the forward peak current density after the 25th cycle is about 21.20 m A cm^-2,and the EOR polarization current density measured at 7200 s remains at the level of 2.03 m A cm^-2.This shows that the newly synthesized Pd-Ni binary composite material is beneficial to the exploration of EOR anode electrocatalyst for fuel cells.4.Preparation of Pd-Ni composite catalyst in sulfuric acid.Using Ni₂O₃,glucose and sulfuric acid solution as starting materials,the precursor was prepared by hydrothermal method assisted air calcination,and the catalyst was obtained by hydrothermal reaction of the precursor with Pd O·H₂O.SEM image results show that different concentration of sulfuric acid solution and different hydrothermal time have a greater impact on particle size and surface morphology.The influence of sulfuric acid solution with different concentration and hydrothermal time on the EOR electrocatalytic performance of the obtained catalyst was investigated.During the precursor preparation process,a precursor was prepared by adding a concentration of 1.5 M sulfuric acid solution and then hydrothermal with Pd O·H₂O for 5 h showed the highest peak current density and polarization current density.