One-Pot Synthesis of Ternary Alloy Hollow Nanostructures with Controlled Morphologies for Electrocatalysis

Abstract

The rational design and synthesis of multimetallic hollow nanostructures (HNSs) have been attracting great attention due to their structural and compositional advantages for application in electrocatalysis. Herein, the one-pot synthesis of Pd–Pt–Ag ternary alloy HNSs with controllable morphologies through a self-templating approach without any pre-synthesized templates is reported. Simultaneous reduction of multiple metal precursors by ascorbic acid in the presence of cetyltrimethylammonium chloride (CTAC) yielded initially metastable Pd–Ag nanocrystals, which can act as a self-template, and subsequent galvanic replacement and reduction led to the formation of final Pd–Pt–Ag HNSs. The size and hollowness (the ratio of inner cavity diameter to outer diameter) of the HNSs could be tuned through control over the concentration of CTAC. This can be attributed to the manipulated reduction kinetics of multiple metal precursors with the change in the CTAC concentration. The prepared Pd–Pt–Ag HNSs exhibited improved catalytic performance for ethanol electro-oxidation due to their large active surface areas and ternary alloy composition.

One-Pot Aqueous Synthesis of Porous Hollow PdCu Alloy Nanoparticles for Enhanced Ethanol Electrooxidation

“…Engineering nanostructures and dimensions of multimetallic Pd-based alloy catalysts is another critical aspect which can optimize their performance in various (electro)­catalysis. Of various nanostructures available, three-dimensional (3D) hollow nanoparticles (HNs) are of special interest in electrocatalysis because of their high surface-to-volume ratio, more catalytically active sites, and enhanced structural stability. − The complexity of Pd-based HNs can be enriched by further engineering their structural parameters, including shell thickness and porosity. − Specifically, Pd-based alloy porous HNs (PHNs) with a thin wall thickness of <5 nm are (electro)­catalytically more active based on their reduced length and penetrated crystalline framework for facilitating both electron and mass transport. , Despite great potentials in (electro)­catalysis, precise synthesis and targeted applications of Pd-based alloy PHNs are still challenging, mostly because of the difficulty and complexity in manipulating either reduction thermodynamics or kinetics involved in simultaneous nucleation of multiple metal precursors along the templates, especially through an easy one-pot aqueous synthetic route.…”

Cu/Co/CoS2 embedded in S,N-doped carbon as highly efficient oxygen reduction and evolution electrocatalyst for rechargeable zinc–air batteries

“…This reveals the advantages of one-pot synthesis, which can boost metal-to-metal interactions and promote the formation of multiphase structures. 60 (iii) The improved performance of S-doped over undoped S materials indicates that the interaction between the sulfide and carbon layers promotes the cleavage of O-O bonds to have low activation barriers. 61,62 C-S is considered to effectively render high spins in surrounding C atoms and facilitate the ORR reaction process thereby.…”

Defect-Rich and Single-Crystalline PdCu Ultrathin Nanowires Promoting Ethanol Oxidation Electrocatalysis

“…Direct ethanol fuel cells (DEFCs) represent an important and very promising subcategory of energy conversion devices based on electrochemical ethanol oxidation reaction (EOR). − Although there have been numerous achievements, their practical applications are still far short of expectations because of the limitations in designing the high-performance EOR electrocatalysts. − Generally, EOR electrocatalysis happened on noble metal (NM) electrocatalysts includes following four key steps: − It is widely accepted that the oxidative removal of poisoning intermediates (for example, (CH 3 CO) ads and CO ads ) is the rate-determining step of EOR electrocatalysis (eq ). Among various NMs, palladium (Pd) is the best NM because of its proper activity and antipoisoning ability, but its stability is still unsatisfactory. − An important solution to enhance the activity and stability is alloying more oxophilic secondary metals, for example, copper (Cu), that not only weakens the affinity of poisoning intermediates through d-band theory but also facilitates the formation of absorbed OH (OH ads ) for removal of poisoning intermediates. ,− However, zero-dimensional (0D) and ultrasmall PdCu nanoparticles, especially with an average diameter of less than 3 nm, generally have a high surface energy, causing inevitable aggregation, resulting in a fast decrease of EOR activity during catalysis due to inherent dissolution and the Ostwald ripening process.…”