Carbon- and Binder-Free Core–Shell Nanowire Arrays for Efficient Ethanol Electro-Oxidation in Alkaline Medium

Abstract

To achieve high electrochemical surface area (ECSA) and avoid carbon support and binder in the anode catalyst of direct ethanol fuel cell, herein, we design freestanding core-shell nickel@palladium-nickel nanowire arrays (Ni@Pd-Ni NAs) without carbon support and binder for high-efficiency ethanol electro-oxidation. Bare Ni nanowire arrays (Ni NAs) are first prepared using the facile template-assistant electrodeposition method. Subsequently, the Ni@Pd-Ni NAs are formed using one-step solution-based alloying reaction. The optimized Ni@Pd-Ni NA electrode with a high ECSA of 64.4 m g exhibits excellent electrochemical performance (peak current density: 622 A g) and cycling stability for ethanol electro-oxidation. The facilely obtained yet high-efficiency core-shell Ni@Pd-Ni NA electrode is a promising electrocatalyst, which can be utilized for oxygen reduction reaction, urea, hydrazine hydrate, and hydrogen peroxide electro-oxidation, not limited to the ethanol electro-oxidation.

Phosphorous incorporation in Pd2Sn alloys for electrocatalytic ethanol oxidation

“…Fig. 3d compares the specific and mass activities of Pd2Sn:P/C with reported Pd-based catalysts showing that the simultaneous incorporation of Sn and P effectively improved the Pd activity toward EOR [9,12,16,[42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58]. Additionally, the potential increase required to rise the current density was also significantly low for Pd2Sn:P/C, especially when compared with commercial Pd/C, as noted in the Tafel plots displayed in Fig.…”

Nanocatalysts for Electrocatalytic Oxidation of Ethanol

“…ZnO template-assisted electrodeposition optimal Pd/Co ratio,a nd hollow and porousstructure 2015 [138] PdCo coreduction synergistic effectfrom the uniques tructure and chemical composition:t hin carbon shelli nhibits particlea gglomeration and alloying with Co modification of the electronic structureo fP d 2017 [139] PdCu coreduction by NaBH 4 3D network, self-supporting, and electronic interactions 2015 [140] PdCu coreduction smaller size, more Pd active sites on the surface, and good synergistic effects 2016 [141] PdCu coreduction by CO ultrathin sheet structure, cleans urfacec lean feature, 3D structure,a nd synergistic effect 2017 [142] PdFe one-pot thermald ecompositiondownward shifted d-bandc enter,easily formed oxygen-containings pecies, and stabilizing effect from supports 2015 [143] PdGe coreduction balance between adsorption energies of CH 3 CO and OH on the catalystsurface and presence of vacanciesi nt he inactive sites 2015 [144] PdNi coreductionsynergistic effectofP dNi particles and rGO support2018 [145] Ni@PdNi electrodepositionand galvanic replacementr eaction bifunctional mechanism that alleviates surface CO poisoning 2018 [146] PdPb coreductionoptimal electronic and geometric effects,a nd stable chemical configuration2 017 [147] PdRu seed-mediated growth optimal Pd/Ru ratio and bifunctional mechanism 2015 [148] PdSn coreductioni nt he presenceo fs ize-and shape-directing agents exposureoffavorable facets 2016 [149] PtCo coreductioni nt he presenceo fs ize-and shape-directing agents presence of activet hreefold hollow sites on platinum-rich high-indexf acets 2016 [150] PtCo coreductionb ycontrolled thermal treatment promotion of partial oxidationo fe thanolover CÀCb ond cleavage Pt 3 Co with Pt skin 2017 [151] PtCu coreductiona td ifferent pH valuesmorphological tailoring 2016 [152] PtCu coreductionmonodispersion,s mall sizes (sub-5 nm), and polyhedral structures 2017 [153] PtIr coreductiondendriticstructures, surface state, and controlled electronic structure2016 [154] PtNi coreductionb yoleylamine synergistic electronic and facet effects2017 [155] PtPd coreductioni nt he presenceo fr GO optimal Pt/Pd ratio, synergistic effect, and ligand effect 2014 [156] PtPd coreductioni nt he presenceo fr GO dendriticstructure, synergistice ffect, and good dispersion of rGO 2014 [157] PtPd coreductioni nt he presenceo fg raphene optimal Pt/Pd ratio and morphology tuning 2014 [158] PtPd coreductionb yNaBH 4 electronic effectsand bifunctional mechanism 2014 …”

Metal Nanotube/Nanowire-Based Unsupported Network Electrocatalysts

“…As a result of the typically high pore density of nanoporous alumina, which is intrinsically linked to the self-ordered pore formation [79], the networks obtained in such templates are relatively dense [83][84][85][86]. In electrochemical applications, such horizontally linked nano-networks show clear advantages compared to their unconnected counterparts ( Figure 7B-F): Parallel 1D nanostructure arrays tend to form bundles [85,87,88], which causes inhomogeneities in the array architecture, compaction and surface area loss at the bundle tips, and stress (most pronounced at the bottom of the nanostructures), making the system susceptible toward nanostructure detachment or breaking ( Figure 7B,C). This degradation mechanism is more severe in the case of 1D nanostructures of higher aspect ratio (length/diameter; see Figure 7A, architecture (iii) versus architecture (iv)) [78,85].…”

“…Alternatively, electroless plating reactions can be chosen which produce intrinsically porous, polycrystalline deposits [65], and pores can be retroactively introduced by restructuring the nanotube walls (e.g., via galvanic replacement [67]). When using galvanic replacement, it must be considered that this technique tends to produces inhomogeneous deposits on complex educt architectures (e.g., caps on the tips of bundled nanowire arrays [87]), due to spatially-decoupled oxidation and reduction reactions. This issue is expected to By applying electroless plating to ion-track etched templates irradiated from multiple directions, self-supported 3D metal nanotube networks have been fabricated from several catalytically interesting transition metals, including Ni [13], Pt [13,98], Cu [13], Ag [13], and Au [13].…”