Monodisperse Sea-Urchin-like Nanodendrites and Nanoparticles of Multicomponent Pd-Based Alloys for Enhanced C₂ Alcohol Oxidation Activity

Abstract

Simultaneous regulation of the morphology and electronic properties of precious metals is essential to achieve satisfactory energy-related electrocatalytic reactions. Herein, we synthesize a class of monodisperse sea-urchin-like nanodendrites (NDs) and monodisperse nanoparticles (NPs) of unary Pd, binary PdM, and ternary PdPbM alloys with face-centered cubic structures in a general way for the ethanol oxidation reaction (EOR), where the morphologies and sizes of two kinds of nanocrystals can be interconverted by changing the solvent (oleylamine/N,N-dimethylformamide, DMF) under the same condition. Interestingly, unveiling the synergistic effect (strain effect and ligand effect) and electronic properties (d-band center) has been proven to learn the mechanism for enhanced electrocatalytic activity. Benefiting from the as-made sea-urchin-like PdPbAg NDs with a tensile strain value of 3.75%, the nanocrystals exhibit excellent electrocatalytic activity in both experiments and theoretical calculations. Also, the sea-urchin-like PdPbAg NDs can serve as an efficient electrocatalyst for the electrochemical alcohol oxidation of methanol, ethylene glycol, and glycerol. This study reports a facile way of constructing monodisperse sea-urchin-like NDs and monodisperse NPs of unary metals and binary/ternary alloys, providing a novel strategy for constructing 3D anisotropic and high-efficiency electrocatalysts, and also offers a deep understanding of lattice engineering and electronic properties with promising applications.

Lattice-Expanded PdAg Spatial Nanodendrites as Catalysts for the Ethanol Oxidation Reaction

“…Under the appropriate catalytic reaction temperature and with the right concentrations of OH – and C 2 H 5 OH, the electrocatalytic conditions promote the EOR process. ,, Figure a delineates the influence of Pd 9 Ag 1 NDs on the current density across a spectrum of catalytic temperatures, concomitant with the modulation of KOH/C 2 H 5 OH concentration from 0.1 to 1.0 mol/L. Thus, it is inferred that an elevation in both the catalytic temperature and the KOH/C 2 H 5 OH molarity enhances the electrocatalytic efficiency of EOR in thermal window of 30 to 50 °C.…”

“…04–0783). The strongest peak is observed between the (111) faces of Pd (41.1°) and Ag (38.1°), indicating that the substitution of Ag atoms in the PdAg NDs results in a slight lattice expansion . The crystallographic values of Pd 7 Ag 1 , Pd 9 Ag 1 , and Pd 11 Ag 1 NDs are 39.30°, 39.34°, and 39.42°, respectively.…”

“…(including eqs –. However, the electrooxidation reaction at the surface of a Pd electrode typically involves an incomplete 4-electron transfer oxidation reaction, as shown in eq , which includes eqs – and ). ,, In practice, the C 2 pathway dominates the EOR process because breaking the C–C bond requires extremely high energy. The EOR process mainly involves the reaction of α–C atoms, rather than β–C atoms. ,,, CH 3 CH 2 normalOH + 16 normalOH − → 2 CO 3 2 − + 11 normalH 2 O + 12 e − Pd − CH 3 CH 2 OH → false( normalPd − normalCH 3 normalCH 2 normalOH normalads false) false( normalPd − normalCH 3 normalCH 2 normalOH normalads false) …”

“…Optimizing the utilization of palladium atoms is at the forefront of current research endeavors . Several methods have been developed to precisely control the morphology, scale, structure, and composition of palladium (Pd)-based nanocatalysts to enhance their catalytic performance. − Several studies have shown that adding a second or third metallic element (M 1 and M 2 ) to palladium-based binary (PdM) or ternary (PdM 1 M 2 ) alloys significantly increases the reaction rates of oxygen reduction reactions (ORR) and alcohol oxidation reactions (AOR). , For instance, a series of porous palladium- and platinum-based alloys were synthesized and exhibited exceptional electrocatalytic properties. − Highly efficient electrode catalysts with ultra-low Pt loadings were obtained by depositing Pt on three-dimensional hydroxylated Ti 3 C 2 T x MXene nanonet or porous carbon substrates. − Alloying processes refine the catalyst’s morphology and electronic configuration, thereby elevating its catalytic efficiency and resistance to poisoning during ethanol oxidation reactions. , The optimized morphology typically contains numerous nanopores and a large specific surface area. Such enhancement can substantially augment ion transport within the nanostructures, thereby offering an abundance of active sites on lattice planes for the catalysis of ethanol oxidation. , Furthermore, the optimized electronic structure enhances KOH/C 2 H 5 OH adsorption and electron transfer during the reaction process, resulting in an improved recovery rate.…”

Bi2Te3 nanosheets promoted Pd for ethylene glycol electrooxidation both in the dark and under visible light irradiation

“…3 To overcome these challenges, researchers have devoted great efforts to improving the utilization and anti-poisoning ability of Pd. 4,5 Replacing conventional carbon black with an oxophilic support, which can promote water dissociation to provide hydroxyl groups (OH ads ) as oxidants for carbon monoxide intermediates (CO ads ), has been recognized as an effective way based on the bi-functional catalytic mechanism. 6,7 Moreover, according to the electronic effect, the intrinsic activity of Pd can be enhanced if its electronic structure can be modulated by the oxophilic carrier to form electron-enriched Pd, which makes the d-band center away from the Fermi level, depressing the adsorption of CO-like intermediates.…”