Ligand Effect of Shape-Controlled β-Palladium Hydride Nanocrystals on Liquid-Fuel Oxidation Reactions

Abstract

The synthesis of shape-, facet-, and composition-controlled Pd-based nanocrystals and the study of their catalytic reaction mechanisms are significant to and challenging for the development of advanced catalysts applicable to direct liquid-fuel cells (DLFCs). In the present study, we prepared (100)-faceted β-PdH cubes and ( 111)faceted β-PdH octahedra, which offered the opportunity to investigate the link between catalytic performance and the shape/facet/composition of nanocrystals. The β-PdH cubes and octahedra remarkably boosted catalytic activity and stability to the formic acid/methanol oxidation reaction (FAOR/MOR), due to the ligand effect originating from the interstitial alloying of β-PdH. Notably in this regard, β-PdH cubes exhibited the highest FAOR/MOR activity among Pdbased catalysts, owing to the relatively high CO tolerance on the Pd(100) facets. Our results confirm that simultaneous control of ligand and facet effects is an effective approach to the design of catalysts suitable for liquid fuel oxidation electrocatalysis.

Boosting Activity and Selectivity of CO2 Electroreduction by Pre‐Hydridizing Pd Nanocubes

“…These phenomena could be attributed to the reduction of the density of state near the Fermi level of PdH 0.40 relative to the Pd counterpart, specifically, the charge transfer between fully filled Pd 4d orbital and half-empty H 1s orbitals. [23][24] These XPS results confirmed the formation of Pd hydride associated with the charge transfer between Pd and H. [20] To perform an electrochemical test, 7 nm Pd and PdH 0.40 NCs were supported on carbon black (Pd NCs/C and PdH 0.40 NCs/C). The CO 2 RR activity and selectivity of 7 nm Pd and PdH 0.40 NCs/C catalysts toward gaseous products were compared by the chronoamperometry (CA) test and gas chromatography (GC) quantification under the operating potential range between −0.5 and −1.0 V ( Figure S5, Supporting Information).…”

How to Remove the Capping Agent from Pd Nanocubes without Destructing Their Surface Structure for the Maximization of Catalytic Activity?

“…At the moment, it is still difficult to resolve the mechanism but our observation was consistent with the results reported by several prior studies involving Pd nanocrystals covered by different types of facets. It is widely recognized that the Pd{100} facets exhibit a higher current density at the peak potential than other types of facets . However, compared with Pd nanocrystals covered by {111} facets or Pd nanoparticles without a well‐defined surface structure, the nanocrystals encased by {100} facets (e.g., nanocubes and right bipyramids) tended to perform poorly at low overpotentials if the {100} facets are covered by halide ions.…”

Synthesis of Pd‐Pt Ultrathin Assembled Nanosheets as Highly Efficient Electrocatalysts for Ethanol Oxidation

“…Polymer electrolyte membrane fuel cells (PEMFCs) are efficient energy converting systems that operate based on the electrooxidation of fuels. [1][2][3][4] PEMFCs potentially have high energy and power densities, but fall short of expectations due to the lack of high-performance electrocatalysts. [5] Pt has been accepted as the most efficient catalyst for fuel oxidation reactions, [6][7][8][9] but has the disadvantages of high cost and low-reserves.…”

“…Polymer electrolyte membrane fuel cells (PEMFCs) are efficient energy converting systems that operate based on the electrooxidation of fuels . PEMFCs potentially have high energy and power densities, but fall short of expectations due to the lack of high‐performance electrocatalysts .…”