Optimizing the ORR activity of Pd based nanocatalysts by tuning their strain and particle size

Abstract

The Fe2O3 shell is in situ formed during the thermal annealing treatment and could effectively prevent the coalescence of Pd2FeCo nanoparticles. Moreover, Pd2FeCo@Pt/C exhibited excellent ORR and Zn–air battery performance, implying that the surface Pt plays an important role in enhancing the activity as well as preventing degradation.

Dendritic defect-rich palladium–copper–cobalt nanoalloys as robust multifunctional non-platinum electrocatalysts for fuel cells

“…The peak positions of Pd 50 Cu 50 , Pd 88 Co 12 , and Pd 59 Cu 30 Co 11 are shifted to higher angles relative to those of the pure Pd crystal (JCPDS-46-1403), indicating that the smaller Cu and Co atoms are incorporated into the Pd lattice. According to the XRD patterns and the Debye–Scherrer equation 46 (Table 1 ), Cu and/or Co entering the Pd lattice can induce lattice contraction and strain variation, and the strain variations of trimetallic PdCuCo nanoalloys (Pd 59 Cu 30 Co 11 :3.50%; Pd 56 Cu 38 Co 6 :2.56%; Pd 62 Cu 16 Co 22 :2.11%) are higher than that of bimetallic Pd 50 Cu 50 (1.62%) and Pd 88 Co 12 (0.72%), which indicates that simultaneously introducing Cu and Co atoms should result in greater strain variation than introducing only Cu or Co in current system and would enhance catalytic performance of nanocrystals 12 , 13 , 39 , 40 , 43 . The results of XRD indicated the formation of Pd, Cu, and Co nanoalloys.…”

Versatile Synthesis of Pd−M (M=Cr, Mo, W) Alloy Nanosheets Flower‐like Superstructures for Efficient Oxygen Reduction Electrocatalysis

“…To address this issue, several strategies, including engineering the microstructures ( e. g ., morphology or defects), tuning surface strain, alloying Pd with cheap and oxyphilic metallic elements, and anchoring on proper support to form well‐coupled nanohybrids, have been taken to tune the surface electronic structure of Pd and optimize its adsorption strength for oxygenated species. Among them, the third strategy has been widely adopted, and some Pd‐based nanoalloys, such as Pd−Mn, Pd−Fe, Pd−Co, Pd−Ni, Pd−Cu, Pd−Pb, Pd−Sn, Pd−Ni−Ag, Pd−Fe−Co, and Pd−Cu−Co, have been explored as candidate catalysts for ORR. Despite that great progress has been achieved, most of reported Pd‐based nanoalloys are focused on 0D, and 1D or twinned nanostructures, and still exhibited insufficient activities (mass activities are often lower than 0.2 A mg −1 ).…”

Unique Half Embedded/Exposed PdFeCu/C Interfacial Nanoalloy as High‐Performance Electrocatalyst for Oxygen Reduction Reaction

“…One of the salient parameters to understand the enhancement of ORR activity is the lattice strain effect in catalysts. The lattice strain changes the d‐band center of the metal catalyst, which resolve the surface oxygen adsorption property on the catalyst surface . A downshift in the d‐band center of Pd weakens the binding energy of absorption of intermediates such as OH − ads and CO ads thereby conserves more active sites on the catalyst surface.…”

“…In addition to this, the ORR activity of noble metals and their compounds are greatly influenced by lattice strain, electronic effect and surface defects . The lattice strain plays an important role in the ORR of noble metal ECs, whereas the compressive lattice strain changes the d‐band center of the metal catalysts which weakens the surface oxygen adsorption property of the catalyst surface . From the electronic effect, the alteration of the d‐band center for Pt or Pd through the formation of alloys with second metal could increase the kinetics of the ORR .…”