Controllable Modification of the Electronic Structure of Carbon-Supported Core–Shell Cu@Pd Catalysts for Formic Acid Oxidation

Abstract

This study analyzes the synthesis of carbon-supported core−shell structured Cu@Pd catalysts (Cu@Pd/C) through a galvanic replacement reaction to be utilized in the electrocatalytic oxidation of formic acid. The strategy used in this study explores the relationship among lattice strain, electronic structure, and catalytic performance. X-ray diffraction and X-ray photoelectron spectroscopy indicate that the inclusion of Cu in the nanocatalyst increases lattice strain and results in a downshift of the d-band of palladium. Electrochemical tests show that Cu@Pd/C catalysts exhibit weaker adsorption strength for CO with increased Cu content, which can be attributed to the downshift of the electronic d-band. For the synthesized materials, the Cu@Pd/ C catalyst with a Cu:Pd atomic ratio of 27:73 is found to have the highest activity for formic acid oxidation. A peaklike plot between activity and atomic composition is acquired and reveals the relationship among lattice strain, electronic structure, and catalytic performance.

Supportless, Bismuth-Modified Palladium Nanotubes with Improved Activity and Stability for Formic Acid Oxidation

“…Strategies centered on alloying to remove CO ads generated by the indirect pathway have been described previously. 6,[12][13][14][15][16][17][18] The addition of adatoms to the catalyst surface, like Bi or Sb, has been shown to improve formic acid electro-oxidation activity at low overpotentials by so-called ensemble or third-body effects. 4,5,[19][20][21][22][23][24][25] Coupled in situ surface-enhanced infrared spectroscopy and first-principles density functional theory (DFT) calculations indicate that the addition of adatoms can influence the configuration of the formic acid molecule at the catalyst surface.…”

Three-dimensional hierarchical porous platinum–copper alloy networks with enhanced catalytic activity towards methanol and ethanol electro-oxidation

“…Moreover, with increasing proportion of Cu, the lattice spacing of (111) plane was further decreased for that of Pt 53 Cu 47 (0.220 nm) as compared to Pt 73 Cu 27 (0.223 nm). Considering the different Pt/Cu ratio for the two alloy (53:47 and 73:27), the lattice difference can be ascribed to the increased lattice contraction as a result of increased proportion of Cu in PteCu alloy [23,32]. The compositions of the PteCu alloy samples were analyzed by energy dispersive X-ray spectroscopy (EDS).…”

Electrocatalysts Prepared by Galvanic Replacement

“…In a search of bimetallic or trimetallic catalysts that show improved activity for formic acid oxidation (FAO) with respect to the best electrode materials of Pd and Pt, galvanic replacement has been used as preparation route (see, for example, [126,[236][237][238][239][240][241][242][243][244][245][246][247][248][249][250][251][252][253]). These include Pt(Ag) and Pd(Ag) [232,241,244], PdAu and PtAu [237,238,245,246,252], PdPb [239], Pt(Bi) [124], Pd(Ni) [249] and Pd(Cu) [247,248] bimetallics as well as Pd(CuFe) [250] and Pt(PdFe) [253] trimetallic systems. The performance improvement of these systems is interpreted in terms of CO poison desorption from Pt in the presence of other metals (where the dehydration mechanism of FAO is operative [235]), and in terms of carbonaceous intermediates removal in the case of Pd (where the dehydrogenation mechanism prevails [235]).…”