Enhanced Electrocatalytic Activity of Alloyed Palladium–Lead Nanoparticles toward Electrooxidation of Ethanol

Abstract

Although many researchers have made great efforts to pursue promising high-efficiency electrocatalysts, a formidable challenge remains for designing excellent palladium-based electrocatalysts for commercializing direct liquid fuel cells. This study reports the synthesis of bimetallic PdPb nanoparticles (NPs) via a mixed solution containing cetyl trimethyl ammonium bromide as the capping agent. Alloyed PdPb NPs are formed, where the size of the NPs increases as Pb atoms are introduced gradually. However, Pd3Pb NPs are obtained with the same molar ratio of Pd and Pb in the raw systems. Among all of the as-made NPs, Pd9Pb1 NPs exhibit superior catalytic activity (2620 mA mg–1) toward ethanol electrooxidation, 4.3 times higher than commercial Pd/C catalysts (613 mA mg–1). The overall rate of the EOR for PdPb NPs is determined, demonstrating that the electrocatalytic activity of the PdPb NPs increases at high catalytic temperatures, in high pH environments, and/or at high ethanol concentrations.

Interfacial Engineering of Porous Pd/M (M = Au, Cu, Mn) Sponge-like Nanocrystals with a Clean Surface for Enhanced Alkaline Electrochemical Oxidation of Ethanol

“…20−27 Also, the greater oxophilicity of the second metals than Pd induces the generation of active oxygenated species (i.e., OH − ) via the H 2 O activation/dissociation in KOH electrolyte, 29 which facilitates the EOR on Pd's active sites along with oxidative removal of poisoning carbonaceous intermediates. [20][21][22][23][24][25][26][27]30 Thus, the electrolyte interaction, interfacial chemistry, charge mobility, and EOR activity of PdM alloy are always superior to mono-Pd nanocrystals. 31−33 Meanwhile, the surface properties of Pd-based alloys play a crucial role in determining their EOR activity and stability, besides understanding their interfacial chemistry during electrochemical EOR.…”

“…Pd-based catalysts are eminent with their superior EOR activity and less susceptible to poisoning by carbonaceous species; − however, their intolerable cost and earth-rarity are critical barriers. − Also, the difficult cleavage of the C–C bond into CO ad and CH ad , besides ease of C–O bond coupling on Pd, which forms acetaldehyde or acetic acid as the preferred product(s), decreases the faradaic efficiency of practical AEFCs. − Potential solutions culminated in tailoring the size and morphology of Pd using supports (i.e., carbon and graphene) and alloying with less expensive and earth-abundant metals (i.e., Cu, Mo, Fe, Mn, Co etc. ). − The latter one is the most promising for promoting EOR performance and reducing consumption of Pd.…”

“…Pd-based catalysts are eminent with their superior EOR activity and less susceptible to poisoning by carbonaceous species; − however, their intolerable cost and earth-rarity are critical barriers. − Also, the difficult cleavage of the C–C bond into CO ad and CH ad , besides ease of C–O bond coupling on Pd, which forms acetaldehyde or acetic acid as the preferred product(s), decreases the faradaic efficiency of practical AEFCs. − Potential solutions culminated in tailoring the size and morphology of Pd using supports (i.e., carbon and graphene) and alloying with less expensive and earth-abundant metals (i.e., Cu, Mo, Fe, Mn, Co etc. ). − The latter one is the most promising for promoting EOR performance and reducing consumption of Pd. The interfacial interaction and alloying effect modulate the d-band center of Pd with respect to the Fermi level, which eases the cleavage of the C–C bond in ethanol at low potential, besides facilitating desorption of intermediates on Pd during EOR electrocatalysis. − Also, the greater oxophilicity of the second metals than Pd induces the generation of active oxygenated species (i.e., OH – ) via the H 2 O activation/dissociation in KOH electrolyte, which facilitates the EOR on Pd’s active sites along with oxidative removal of poisoning carbonaceous intermediates. − , Thus, the electrolyte interaction, interfacial chemistry, charge mobility, and EOR activity of PdM alloy are always superior to mono-Pd nanocrystals. − Meanwhile, the surface properties of Pd-based alloys play a crucial role in determining their EOR activity and stability, besides understanding their interfacial chemistry during electrochemical EOR.…”

“…). − The latter one is the most promising for promoting EOR performance and reducing consumption of Pd. The interfacial interaction and alloying effect modulate the d-band center of Pd with respect to the Fermi level, which eases the cleavage of the C–C bond in ethanol at low potential, besides facilitating desorption of intermediates on Pd during EOR electrocatalysis. − Also, the greater oxophilicity of the second metals than Pd induces the generation of active oxygenated species (i.e., OH – ) via the H 2 O activation/dissociation in KOH electrolyte, which facilitates the EOR on Pd’s active sites along with oxidative removal of poisoning carbonaceous intermediates. − , Thus, the electrolyte interaction, interfacial chemistry, charge mobility, and EOR activity of PdM alloy are always superior to mono-Pd nanocrystals. − Meanwhile, the surface properties of Pd-based alloys play a crucial role in determining their EOR activity and stability, besides understanding their interfacial chemistry during electrochemical EOR. For instance, the EOR mass activity of PdAg anchored on a multiwalled carbon nanotube (Pd 3.5 Ag/MWCNT) (3.72 A/mg Pd ) was 7.54 times higher than a commercial Pd/C catalyst (0.49 A/mg Pd ), due to the alloying effect and high dispersion of Pd 3.5 Ag, besides its improved electronic interaction with MWCNT .…”

Two-Dimensional Metal–Organic Frameworks as Ultrahigh-Performance Electrocatalysts for the Fuel Cell Cathode: A First-Principles Study

“…The severe depletion of fossil energies (e.g., oil and coal) and worrisome environmental issues (e.g., acid rains and greenhouse effect) motivate tremendous research interests to explore and use sustainable clean energies. − Proton exchange membrane fuel cells (PEMFCs) are an eco-friendly device that directly converts the clean hydrogen energy into electric energy, with water and heat as byproducts . In PEMFCs, compared with the fast kinetics of the hydrogen oxidation reaction that occurs at the anode, the activation of oxygen molecules in the oxygen reduction reaction (ORR) that occurs at the cathode is more difficult, which is the main problem that has plagued researchers for a long time. , Although Pt catalysts can effectively accelerate the ORR kinetics, their inherent disadvantages (e.g., high cost, limited reserves, and poor durability) limit their further large-scale commercialization.…”