Self-supported porous Ni-Fe-P nanocomposite cathode was fabricated via a direct reaction between metallic foam (Ni-Fe) and P vapor. Microstructure characterization results confirm that, after the reaction with P vapor, the metallic framework including Ni and Fe was converted into corresponding metallic phosphide compounds (i.e., Ni2P, Ni5P4 and Fe2P) and quantities of nanosheet arrays vertically-grown on the ligament. Both in acidic (0.5 M H2SO4) and alkaline (1.0 M KOH) media, the as-obtained Ni-Fe-P electrode demonstrates a quite high HER catalytic performance as compared with pristine Ni and Ni-Fe foam, even being almost close to state-of-the-art Pt/C. The as-evolved typical micro-nano hierarchical 3D integrated framework coupled with quantities of nanosheet arrays on it should be responsible for the great HER performance of this resulting composite cathode, which provides not only fast channels for electron transfer but also offers large electrochemical surface area so as to expose more active sites toward the electrocatalysis for HER. Meanwhile, the synergistic effect between the three active Ni2P, Ni5P4 and Fe2P phase may also play a crucial role in the as-revealed superior HER activity. These excellent results promise the potential application of this typical kind of multi-component Ni-Fe-P cathode toward electrochemical water splitting for large-scale hydrogen fuel production.

A series of trimetallic PdSnPtx (x = 0.1–0.7)/C catalysts with varied Pt content have been synthesized by co-reduction method using NaBH4 as a reducing agent. These catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and chronoamperometry (CA). The electrochemical results show that, after adding a minor amount of Pt dopant, the resultant PdSnPtx/C demonstrated more superior catalytic performance toward ethanol oxidation as compared with that of mono-/bi-metallic Pd/C or PdSn/C in alkaline solution and the PdSnPt0.2/C with optimal molar ratio reached the best. In acid solution, the PdSnPt0.2/C also depicted a superior catalytic activity relative to the commercial Pt/C catalyst. The possible enhanced synergistic effect between Pd, Sn/Sn(O) and Pt in an alloyed state should be responsible for the as-revealed superior ethanol electro-oxidation performance based upon the beneficial electronic effect and bi-functional mechanism. It implies the trimetallic PdSnPt0.2/C with a low Pt content has a promising prospect as anodic electrocatalyst in fields of alkali- and acid-type direct ethanol fuel cells.

In this study, we have synthesized a series of carbon supported PdSn(molar ratio 1:1), PdSnAg(2:2:1), PdSnNi(2:2:1) and PdSnCo(2:2:1) catalysts by a borohydride reduction method. These catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and chronoamperometry (CA). As compared with PdSn/C, the trimetallic catalysts show a significant activity enhancement for ethanol and formic acid electro-oxidation. Moreover, the PdSnAg/C catalyst exhibits the highest activity together with much better stability. The activity enhancement of PdSnAg/C can be rationalized by the synergistic effect of Pd-SnO2-Ag clusters on the superficial surface of catalyst, such as bi-functional mechanism, superior electronic structure, excellent electric conductivity, etc. In addition, both ethanol and formic acid electro-oxidation reactions on the PdSnAg/C catalyst are diffusion-controlled and represent good linear correlation with ethanol and formic acid concentrations.

•Pd-based bi-/ternary catalysts were synthesized with Sn or/and Cu as alloying element.•PdCuSn/CNTs exhibits the highest activities for targeted molecules electro-oxidation.•Activity enhancement may derive from distinct effect by alloying with Cu and Sn.•Alloying of Sn is even more remarkable for ethanol and formic acid oxidation.In this study, we have synthesized a series of multi-walled carbon nanotubes supported Pd, PdCu(molar ratio 1:1), PdSn(1:1) and PdCuSn(1:1:1) catalysts by chemical reduction with NaBH4 as a reducing agent. These catalysts are characterized using X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry and chronoamperometry. During the potential cycling activation, it is found that the additive Cu is prone to suffer leaching while the dissolution of Sn rarely occurs. Electrochemical measurements demonstrate that, the co-alloying of Pd with Cu and Sn can trigger the best catalytic activity enhancement as compared with the binary PdCu/CNTs, PdSn/CNTs and mono-component Pd/CNTs catalysts. The PdCuSn/CNTs reveals the most excellent activities toward methanol, ethanol and formic acid electro-oxidation and the corresponding mass activity can attain to 395.94, 872.70 and 534.83 mA mg−1 Pd, respectively. The possible promotion effect of additive Sn or/and Cu on the electrocatalytic activity improvement is also analyzed.

Using the electro-spark deposition technique, a novel kind of Pd/TM (TM = Ni, Co and Ti) electrode was successfully prepared by arc-depositing Pd on the transition metal substrates. The structure, morphology and chemical composition of the arc-deposited films were investigated using thin-film X-ray diffraction (TF-XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The results show that, a coarsening topographical morphology can be obtained, being composed of numerous craters/spots with sizes ranging from nano-scales to several microns. The electrochemical measurements indicate that the arc-deposited Pd/TM electrodes exhibit distinct electrochemical behaviors and the catalytic activity toward ethanol electro-oxidation reaction (EOR) is highly dependent upon the nature of substrate. Among the Pd/TM electrodes investigated, the arc-deposited Pd/Co reveals the best activity and superior poisoning tolerance towards ethanol oxidation and will find promising applications as a candidate for the anode catalyst of direct ethanol fuel cells (DEFCs).

•Nanoporous PdAu catalyst can be fabricated by dealloying of AlPdAu ternary alloy.•Nanoporous PdAu catalyst exhibits enhanced activity for methanol electro-oxidation.•Alloying Au facilitates CO-like species oxidation and active Pd sites recovery.Nanoporous PdAu catalyst (NP-PdAu) can be fabricated by chemical dealloying ternary AlPdAu alloy in the alkaline solution. Electrochemical measurements demonstrate that the NP-PdAu exhibits greatly enhanced catalytic activity and long-term stability toward methanol electro-oxidation. The as-revealed specific activity and mass activity can attain to 1.30 mA cm−2 and 866.50 mA mg−1 (Pd), respectively, which is significantly higher than that of monometallic NP-Pd, NP-Au and widely-reported Pd or Pd-based nanoparticle catalysts. Moreover, methanol oxidation reaction on the NP-PdAu electrode is diffusion-controlled and represents a good linear correlation with methanol concentration. The results indicate that NP-PdAu is attractive as a promising electrocatalyst of alkali-type direct methanol fuel cells (DMFCs).