The Promotional Effect of Rare Earth on Pt for Ethanol Electro-Oxidation and Its Application on DEFC

Abstract

Bimetallic Pt3Eu/C, Pt3La/C, and Pt3Ce/C electrocatalysts have been prepared, characterized, and tested for ethanol electro-oxidation (EEO). The materials were synthesized by chemical reduction with NaBH4, rendering nanosized particles with actual compositions close to the nominals and no alloy formation. X-ray photoelectron spectroscopy (XPS) confirmed that the auxiliary rare-earth metals were present on the surface in oxide form. The electrochemical analyses in acid and alkaline EEO evidenced that, compared to Pt/C, the addition of rare earth metals in the form of oxides reduced the onset potential, increased the current density, and enhanced the stability. The results were fully confirmed in the DEFC single-cell measurements. Finally, the presence of rare earth metals in the oxidized form increased the percentage of acetic acid as the final product, making the electrocatalysts more selective and efficient than Pt/C, where acetaldehyde was the main product.

Boosting the Electrolysis of Monosaccharide-Based Streams in an Anion-Exchange Membrane Cell

“…Figure a displays the XRD patterns of the GNPs support and anodic electrocatalysts. The GNPs support showed a sharp peak at a diffraction angle of 2θ = 26.26° corresponding to the (002) reflection of hexagonal graphitic structures, hence demonstrating the highly crystalline morphology of this material. , This peak was also observed in the electrocatalysts to a lesser extent. Other minor peaks at diffraction angles of 42.78°, 43.94°, 54.14°, and 77.38° were also observed in the GNPs pattern, which were attributed to (100), (101), (004), and (110) reflections of graphitic structures (JCPDS no.…”

“…These results, along with those related to mass activity, demonstrate the positive effect of adding Ni on both the electrochemical activity and the mass of Pt used. This can be explained according to three factors: first, the oxophilicity of Ni, which is an inherent property that facilitates the dissociation of water molecules and the formation of oxidized species (principally NiOOH), especially in alkaline media and at higher elevated potentials. , These compounds enhance the oxidation and desorption of intermediate reaction products derived from the d -glucose electro-oxidation and their subsequent release from neighboring Pt active sites through the bifunctional or Langmuir–Hinshelwood mechanism. , The second contribution could be ascribed to the ligand effect. i.e., the variation in the electronic density of Pt due to the alloy formation with Ni, which may affect the adsorption of d -glucose molecules and the subsequent electro-oxidation process. , The third contribution involves the blockage of certain Pt sites by Ni atoms, favoring certain reaction pathways without reducing the electrocatalytic activity (ensemble effect) …”

“… 44 , 45 These compounds enhance the oxidation and desorption of intermediate reaction products derived from the d -glucose electro-oxidation and their subsequent release from neighboring Pt active sites through the bifunctional or Langmuir–Hinshelwood mechanism. 24 , 46 The second contribution could be ascribed to the ligand effect. i.e., the variation in the electronic density of Pt due to the alloy formation with Ni, which may affect the adsorption of d -glucose molecules and the subsequent electro-oxidation process.…”