Carbon supported PdO with improved activity and stability for oxygen reduction reaction in alkaline solution

Metal-Support Interactions in PdCu/NiZnP Nanohybrids Enhance Alcohol Electrooxidation

Developing high-performance catalysts for the alcohol electrooxidation reaction is of significant importance for the practical application of direct fuel cells. Herein, a supported catalyst consisting of well-dispersive PdCu nanoparticles (NPs) and ultrathin NiZnP nanosheets (NSs) is synthesized. The high-surface-area NiZnP NSs provide a platform for good dispersion of PdCu NPs, resulting in stable catalysts with a large number of exposed surface atoms. Compared with PdCu NPs and commercial Pd/C, the metal-support interactions contribute to the activity and durability improvement of the PdCu/NiZnP nanohybrids. Moreover, the NiZnP NSs promote the formation of OH species, thereby facilitating the removal of carbonaceous intermediates and ensuring the long-term stability of PdCu/NiZnP nanohybrids. This study provides deep insight into the supported catalysts and a comprehensive understanding of the metal-support interactions, offering great opportunities for the design of efficient catalysts for direct fuel cells.

Uniform Distribution of Pd on GO-C Catalysts for Enhancing the Performance of Air Cathode Microbial Fuel Cell

Metal, as a high-performance electrode catalyst, is a research hotspot in the construction of a high-performance microbial fuel cell (MFC). However, metal catalyst nanoparticles and their dispersed carriers are prone to aggregation, producing catalytic electrodes with inferior qualities. In this study, Pd is uniformly dispersed on the graphene framework supported by carbon black to form nanocomposite catalysts (Pd/GO-C catalysts). The effect of the palladium loading amount in the catalyst on the catalytic performance of the air cathode was further studied. The optimized metal loading afforded a reduced resistance and improved accessibility of Pd particles for the ORR. The maximum current output of the 0.250 Pd (mg/cm2) MFC was 1645 mA/m2, which is 4.2-fold higher than that of the carbon paper cathode. Overall, our findings provide a novel protocol for the preparation of high-efficient ORR catalyst for MFCs.

Palladium Oxide Nanoparticles: Preparation, Characterization and Catalytic Activity Evaluation

Stable palladium oxide nanoparticles were prepared in aqueous suspension with a very simple procedure, by dissolving palladium nitrate in water at a concentration around 10−4 M. UV-visible absorption spectroscopy was adopted to follow the formation of these nanoparticles, which were characterized by TEM microscopy, along with XRD, XPS and Raman measurements. DFT calculations allowed to interpret the Raman data and to clarify the species present at the surface of the nanoparticles. The catalytic activity of the latter was evaluated by monitoring the reduction of p-nitrophenol to p-aminophenol. This investigation paves the way to the use of these colloidal nanoparticles in processes of heterogeneous catalysis, in particular those concerning the catalytic degradation of aromatic derivatives that represent a serious danger for the environment as pollutants, as in the case of p-nitrophenol.

Effect of thermal treatment of Pd decorated Fe/C nanocatalysts on their catalytic performance for formic acid oxidation

The thermal treatment of bimetallic nanocatalysts plays an important role in determining their catalytic performance. Here tuning the surface oxidized metal species of bimetallic Pd-Fe electrocatalysts for the formic acid (FA) oxidation reaction is reported and a correlation between the surface oxidized metal species of the Pd-Fe nanoparticles and their catalytic activities is proposed. The structural details of the Pd-Fe/C catalysts are characterized by X-ray diffraction, X-ray photoelectron spectroscopy and high-sensitivity low-energy ion scattering (HS-LEIS). Cyclic voltammetry measurements demonstrated that the mass activity of the Pd-Fe nanoparticles with a molar ratio of Pd/Fe = 1/15 is about 7.4 times higher than that of Pd/C. This enhancement could be attributed to the synergistic effect between Pd(0) and Pd oxidized species on the surface of the Pd-Fe/C treated sample and electronic effects. This finding demonstrates the importance of surface oxidized metal species at the nanoscale in harnessing the true electrocatalytic potential of bimetallic nanoparticles and opens up strategies for the development of highly active bimetallic nanoparticles for electrochemical energy conversion.

Insights into the spontaneous formation of hybrid PdO x /PEDOT films: electroless deposition and oxygen reduction activity

Hybrid palladium oxide/poly(3,4-ethylenedioxythiophene) (PdO_x/PEDOT) films were prepared through a spontaneous reaction between aqueous PdCl₄²⁻ ions and a nanostructured film of electropolymerized PEDOT. Spectroscopic and electrochemical characterization indicate the presence of mixed-valence Pd species as-deposited (19 ± 7 at% Pd⁰, 64 ± 3 at% Pd²⁺, and 18 ± 4 at% Pd⁴⁺ by X-ray photoelectron spectroscopy) and the formation of stable, electrochemically reversible Pd⁰/α-PdO_x active species in alkaline electrolyte and furthermore in the presence of oxygen. The elucidation of the Pd speciation as-deposited and in solution provides insight into the mechanism of electroless deposition in neutral aqueous conditions and the electrocatalytically active species during oxygen reduction in alkaline electrolyte. The PdO_x/PEDOT film catalyses 4e⁻ oxygen reduction (n = 3.97) in alkaline electrolyte at low overpotential (0.98 V vs. RHE, onset potential), with mass- and surface area-based specific activities competitive with, or superior to, commercial 20% Pt/C and state-of-the-art Pd- and PEDOT-based nanostructured catalysts. The high activity of the nanostructured hybrid PdO_x/PEDOT film is attributed to effective dispersion of accessible, stable Pd active sites in the PEDOT matrix.

Hybrid PdO_x/PEDOT films efficiently catalyse the direct 4e⁻ oxygen reduction reaction in alkaline electrolyte.

Effect of catalyst carbon supports on the oxygen reduction reaction in alkaline media: a comparative study

Four common catalyst carbon supports are quantitatively compared in an integrated study towards the oxygen reduction reaction in alkaline media.