Modulating the surface segregation of PdCuRu nanocrystals for enhanced all-pH hydrogen evolution electrocatalysis

Abstract

Core–shell PdCuRu trimetallic nanocrystals with a Pd-rich shell can be obtained by leveraging controlled surface segregation, and high-performance HER catalytic activity finally was achieved at all pH values.

Exclusive Strain Effect Boosts Overall Water Splitting in PdCu/Ir Core/Shell Nanocrystals

“… [37] The positively shift of the reduction potentials of PdCu/Ir also indicate the weakened binding strength of the oxygenated species (Figure 4 e). [28, 45] In terms of the utilization of Ir atoms, Ir‐based mass activity of PdCu/Ir/C is still far higher than the alloyed PdCuIr/C catalyst and other catalysts (Figure S11). Compared with the other state‐of‐the‐art Ir‐based electrocatalysts toward HER, the PdCu/Ir/C also shows lower overpotential and higher mass activity (Figure 4 f & Table S2) [37, 49–54] …”

Highly Porous MIL-100(Fe) for the Hydrogen Evolution Reaction (HER) in Acidic and Basic Media

“…The exchange current density, also given by j o , can be accessed by the intrinsic rate electron transfer via extrapolation. 54 The value j o was calculated to be 76.44 mA cm –2 with an overpotential of 150.57 mV. In general, three major steps are regarded for converting H + to H 2 toward the HER in acidic medium commonly termed the Volmer, Heyrovsky, and Tafel process, corresponding to a proton electrosorption ( eq 4 ), desorption via electrochemical represents ( eq 5 ), and the surface-adsorbed hydrogen recombination ( eq 6 ) to the initial absorption of protons from acid solution to form absorbed (H → H ad ) and generally regarded as the fast reaction.…”

Exclusive Strain Effect Boosts Overall Water Splitting in PdCu/Ir Core/Shell Nanocrystals

“…[37] The positively shift of the reduction potentials of PdCu/Ir also indicate the weakened binding strength of the oxygenated species (Figure 4e). [28,45] In terms of the utilization of Ir atoms, Ir-based mass activity of PdCu/Ir/C is still far higher than the alloyed PdCuIr/C catalyst and other catalysts ( Figure S11). Compared with the other state-of-the-art Ir-based electrocatalysts toward HER, the PdCu/Ir/C also shows lower overpotential and higher mass activity (Figure 4f &T able S2).…”

“…Figure 3a,b &S9show the Pd 3d, Ir 4f and Cu 2p spectra of PdCu/Ir and PdCuIr nanocrystals,r espectively.T he Pd 3d spectra can be divided into two peaks corresponding to the Pd 3d 5/2 and Pd 3d 3/2 states,a nd be further split into two double peaks assigned to the Pd 0 and Pd 2+ chemical states.S imilarly,t he Cu 2p and Ir 4f spectra also show two pairs of doublets,associated with Cu 0 2p 3/2 ,Cu 0 2p 1/2 ,Cu 2+ 2p 3/2 ,Cu 2+ 2p 1/2 and Ir 0 4f 7/2 ,Ir 0 4f 5/2 ,Ir 4+ 4f 7/2 ,Ir 4+ 4f 5/2 ,r espectively.A ll the metal atoms in both PdCuIr and PdCu/Ir nanocrystals are mainly in the metallic state.N oted that both Pd 3d and Cu 2p spectra of PdCu/Ir are negatively shifted to higher binding energies compared with those of PdCuIr alloys,w hile the Ir 4f spectra are blueshifted positively.Such strongly peak shift visualizes astrong change in the surface electronic structure of PdCu/Ir nanocrystals, originated from inter-atomic or intra-atomic charge transfer from Ir to Pd or Cu, which leads to aw eak adsorption for reaction intermediates on the surface of PdCu/Ir nanocrystals. [43][44][45] Them odified adsorption/desorption energy of reaction intermediate is in line with d-band center downward relative to the Fermi level, thus affecting the electrocatalytic activity. [45,46] DFT calculations were further performed to provide insights into the origin of the enhanced OER performance on…”

“…[43][44][45] Them odified adsorption/desorption energy of reaction intermediate is in line with d-band center downward relative to the Fermi level, thus affecting the electrocatalytic activity. [45,46] DFT calculations were further performed to provide insights into the origin of the enhanced OER performance on…”