Functional Surfactant-Induced Long-Range Compressive Strain in Curved Ultrathin Nanodendrites Boosts Electrocatalysis

Abstract

Curved ultrathin PtPd nanodendrites (CNDs) with long-range compressive strain and highly branched feature are first prepared by a functional surfactant-induced strategy. Precise synthesis realized the construction of both curved and flat PtPd nanodendrites (NDs) with the same atomic ratio, which contributed to exploration of the strain effect on electrocatalytic performance alone. Abundant evidence is provided to confirm that the long-range compressive strain in curved PtPd architectures can effectively tailor the local coordination environment of active sites, lower the position of the d-band center, weaken the adsorption energy of the intermediates (e.g., H* and CO*), and ultimately increase their intrinsic activity. The density functional theory (DFT) calculations further reveal that the introduction of compressive strain weakens the Gibbs free-energy of the intermediate (ΔG H* ), which is favorable for accelerating the hydrogen evolution reaction (HER) kinetics. A similar enhanced electrocatalytic performance can also be found in the methanol oxidation reaction (MOR).

Large Au@Pd/PdOx core–porous shell nanoparticles as efficient ethanol oxidation electrocatalysts

“…The high electrocatalytic activity and durability should be mainly ascribed to the porous structure of the Pd shells, which offer more active sites and allow the reactants to enter and contact the inner Pd shell. 47,48 A close relationship between the proportion of surface PdO in Au@Pd core–porous shell NPs and the electrocatalytic activity was observed. According to previous reports, a thin layer of PdO on Pd can strongly bind with ethanol and its intermediate species and result in a high current density of electrocatalytic oxidation of ethanol.…”

Low-Pt Octahedral PtCuCo Nanoalloys: “One Stone, Four Birds” for Oxygen Reduction and Methanol Oxidation Reactions

“…The smaller Tafel slope of Pt 0.23 Cu 0.64 Co 0.13 /C (in acid, 134 mV dec –1 (Figure d); in alkaline, 157 mV dec –1 (Figure e)), as compared with Pt/C (in acid, 352 mV dec –1 (Figure d); in alkaline, 220 mV dec –1 (Figure e)), showed that Pt 0.23 Cu 0.64 Co 0.13 /C had faster kinetics of the MOR, thus resulting in an enhanced activity. The activity enhancement of the MOR could be explained by the electron effect (the strain effect caused by the mismatch of the lattice constant and the ligand effect caused by the electronic state change) and the synergistic/bifunctional effect of the alloying PtCuCo nanooctahedron. , On one hand, the electron effect (i.e., compressive strain and/or ligand effect) that was triggered by the introduction of Cu and Co favored a weakening of the adsorption strength of the carbon-containing intermediate species that were adsorbed on the Pt sites. On the other hand, the surface oxyphilic Cu and Co sites would activate water and provide more reactive oxygen species (Cu-OH ads and Co-OH ads ), which were expected to oxidize the strongly adsorbed CO ads species on adjacent Pt sites (Pt-CO ads ) by a so-called synergistic/bifunctional effect. , It was easier to oxidize CO on Pt 0.23 Cu 0.64 Co 0.13 /C than on Pt/C, which was confirmed by CO stripping experiments in both acidic and alkaline electrolytes.…”

“…The activity enhancement of the MOR could be explained by the electron effect (the strain effect caused by the mismatch of the lattice constant and the ligand effect caused by the electronic state change) and the synergistic/bifunctional effect of the alloying PtCuCo nanooctahedron. 59,60 On one hand, the electron effect (i.e., compressive strain and/or ligand effect) that was triggered by the introduction of Cu and Co favored a weakening of the adsorption strength of the carbon-containing intermediate species that were adsorbed on the Pt sites. On the other hand, the surface oxyphilic Cu and Co sites would activate water and provide more reactive oxygen species (Cu-OH ads and Co-OH ads ), which were expected to oxidize the strongly adsorbed CO ads species on adjacent Pt sites (Pt-CO ads ) by a so-called synergistic/bifunctional effect.…”

Synthesis and Prospects of Holey Two‐dimensional Platinum‐group Metals in Electrocatalysis

“…This approach is extremely flexible for achieving step‐by‐step sequential epitaxial growth and obtaining 2D core‐shell Pt‐Pd NDs as bimetallic products. The coreduction of multiple metal precursors following the formation of lamellar organic‐inorganic hybrids to enable the nanoconfined in‐plane epitaxial growth of bimetallic nuclei into a variety of highly branched and ultrathin NDs, such as Pt‐Ru NDs, [22] Pt‐Rh NDs, [22] PD‐Pt NDs, [23] and other materials, has also been explored.…”