Methanol Oxidation Reaction In Alkaline Media Research Articles

Synergetic effect of Ni substitution and induced porosity: Enhancing the electrocatalytic performance of cobaltite towards OER and MOR in alkaline medium

The quest for sustainable and efficient energy conversion technologies has intensified research into advanced materials for electrochemical reactions, such as the oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). Transition metal oxides have emerged as promising catalysts due to their abundance, low cost, and adjustable electronic properties. Among these, Nickel (Ni)-based compounds are particularly noteworthy for their catalytic activity and stability. This research paper explores the crucial impact of Nickel (Ni) substitution and introducing porosity on the valence states of metal ions and their mass transport in the context of OER and MOR. In this study, we present a step-by-step surfactant (Brij 58) assisted synthesis approach for the preparation of mesoporous Co3O4 and NiCo2O4. The synthesised material has been physiochemically characterised by Fourier transform Infrared Spectroscopy (FTIR), Scanning electron microscopic/Energy-dispersive X-ray spectroscopy (SEM/EDS) and High-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), and inductively coupled plasma mass spectrometry (ICP-MS) analyses. Additionally, the impact of these alterations on electrocatalytic activity, reaction kinetics, and electrochemical stability during OER/MOR has been explored by Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), Tafel, Electrochemical Impedance Spectroscopy (EIS) and chronoamperometric experiments. Mesoporous NiCo2O4 exhibits exceptional electrocatalytic performance with current densities of 46.8 mA/cm2 for OER and 214.5 mA/cm2 for MOR at 550 mV. By shedding light on the intricate interplay between metal substitution, porosity, and valence states, this research aims to provide valuable insights for the evolution of enhanced cobaltite electrocatalysts for sustainable water splitting and MOR.

Rational Design of NiZnx@CuO Nanoarray Architectures for Electrocatalytic Oxidation of Methanol.

Methanol oxidation reaction (MOR) in anodes is one of the significant aspects of direct methanol fuel cells (DMFCs), which also plays a critical role in achieving a carbon-neutral economy. Designing and developing efficient, cost-effective, and durable non-Pt group metal-based methanol oxidation catalysts are highly desired, but a gap still remains. Herein, we report well-defined hierarchical NiZnx@CuO nanoarray architectures as active electrocatalysts for MOR, synthesized by combining thermal oxidation treatment and magnetron sputtering deposition through a brass mesh precursor. After systematically evaluating the electrocatalytic performance of NiZnx@CuO nanoarray catalysts with different preparation conditions, we found that the NiZn1000@CuO (thermally oxidized at 500 °C for 2 h, nominal thickness of the NiZn alloy film is 1000 nm) electrode delivers a high current density of 449.3 mA cm-2 at 0.8 V for MOR in alkaline media as well as excellent operation stability (92% retention after 12 h). These outstanding MOR performances can be attributed to the hierarchical well-defined structure that can not only render abundant active sites and a synergistic effect to enhance the electrocatalytic activity but also can effectively facilitate mass and electron transport. More importantly, we found that partial Zn atoms could leach from the NiZn alloy, resulting in rough surface nanorods, which would further increase the specific surface area. These results indicate that the NiZn1000@CuO nanoarray architecture could be a promising Pt group metal alternative as an efficient, cost-effective, and durable anode catalyst for DMFCs.

Highly Active Lanthanum Perovskite Electrocatalysts (LaMnxCo1-xO3 (0 ≤ x ≤ 1)) by Tuning the Mn:Co Ratio for ORR and MOR in Alkaline Medium

AbstractLanthanum-based perovskites (LaMnxCo1-xO3 (0 ≤ x ≤ 1)) were synthesized using a solution combustion synthesis technique with variable ratios of Co and Mn to investigate the surface property and electrocatalytic characteristics (stability and activity of catalyst) for methanol oxidation reaction (MOR), oxygen reduction reaction (ORR), and oxygen evolution reaction (OER) under alkaline medium (KOH). The structural, chemical, and morphological characterizations of the synthesized catalyst were performed by XRD, FTIR, SEM, TEM, and XPS techniques as a function of the Mn:Co elemental ratio. The time–temperature profile during the combustion process was also monitored to study the completion of the combustion reaction and to understand its impact on the structure of the perovskites. SEM/EDX and XPS analysis confirmed the formation of the targeted ratio of Mn and Co on the catalyst. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) results revealed that all perovskite samples with different Co:Mn ratios were active for ORR, OER, and MOR. The LaMnxCo1-xO3 perovskite with x = 0.4 showed the highest current density compared to the other samples toward all the electrocatalytic reactions under alkaline reaction conditions. Graphical Abstract

A novel pomegranate-inspired bifunctional electrode materials design for acetylcholinesterase biosensor and methanol oxidation reaction

A pomegranate-inspired bifunctional electrode material based on Ni/NiO nanoparticle embedded in nitrogen-doped, partially graphitized carbon framework (Ni/NiO@NPGC) was designed and prepared for the construction of novel electrochemical biosensor and methanol oxidation reaction (MOR). Profiting from itsspecialstructureandfunction, Ni/NiO@NPGC was employed as a matrix immobilizing acetylcholinesterase (AChE) for methyl parathion (MP) sensor. The developed biosensor was proved to have wide linear range (1.0 × 10-14-1.0 × 10-8 g mL−1), low detection limit (3.5 × 10-15 g mL−1), and good stability for the determination of MP in practical samples. In addition, the Ni/NiO@NPGC electrode exhibited high electrocatalytic activity (specific activity 73.1 mA cm−2) and durability for the MOR in alkaline medium. The results were mainly attributed to the pomegranate-like architecture structure with pyridinic N and carbon frame of Ni/NiO@NPGC, which ensured the electrochemical activities of all nanoparticles and immobilization of enzyme. In addition, the metal oxide was well dispersed to prevent from self-agglomeration and kept mass transfer paths. The work provides a reference for the development of high-performance bifunctional electrode material for the biosensor and MOR.

Design of Co-Sn bimetallic nanoalloys as electrocatalyst for alkaline methanol oxidation reaction: Exploring the effect of electroactivation process

The engineering of cost-effective and durable electrocatalysts for the methanol oxidation reaction (MOR) is required for the commercialization of direct methanol fuel cells (DMFCs). Herein, a series of Cox-Sn100-x alloy nanoparticles were synthesized to optimize the Co/S ratio, and the alloy nanoparticle which offered the best electrochemical performance towards MOR was employed as electrocatalyst for further experiments. Moreover, two different electroactivation approaches including i) activation in phosphate buffer medium, and ii) in-situ activation were explored to enlighten their effect on electrochemical characteristics of nanocatalyst. In this regard, the chronoamperometry measurements were carried out at a constant potential over a fixed period of 300 s. Additionally, the pH of the phosphate buffer solution in a range of 3–12, the activation potential ranging −0.7 V to −2.0 V were optimized by evaluating the recorded cyclic voltammograms. Moreover, to predict the effect of phosphate buffer pH in the activation process on the electrocatalytic activity of catalyst were artificial neural network (ANN) approach was implemented. Amongst the various nanoalloys, Co65-Sn35 nanoparticles were determined as the optimal one thanks to their uniform dispersion and less aggregation feature. In the activation process with phosphate buffer at pH of 10 was determined as the optimal, and at this condition a hydrogen evolution reaction also occurred in the range of applied activation potential. The findings revealed that activation in phosphate buffer solution led to the formation of more –OH species, thereby boosting the electrocatalytic activation towards MOR in alkaline media. Similarly, for the in-situ activation approach, the optimum potential was determined as −1.3 V to achieve the maximum current density. The findings offered that the electroactivation in phosphate buffer solution (pH = 10) at −1.3 V could result in a highly active electrocatalyst to be utilized in alkaline DMFCs. This research lays the door for tailoring high-performance, low-cost electrocatalysts that could be used in energy conversion systems instead of commercial noble-metal-based electrocatalysts.

Highly efficient methanol oxidation reaction on durable Co9S8 @N, S-doped CNT catalyst for methanol fuel cell applications

The implementation of direct methanol fuel cells is seen as a reliable factor in the future energy mix. Efficient energy conversion from methanol requires an active and durable catalyst to drive the anodic methanol oxidation reaction (MOR) in direct methanol fuel cells. As an alternative to high cost noble metals, cobalt-based electrocatalysts are considered potential replacements that meet the high activity and long-term stability for MOR. Herein, we report the preparation of hierarchical Co9S8 nanowires trapped in N-doped carbon nanotubes (N,S–Co@CNT) derived from melamine showing high activity for MOR in alkaline medium. In order to identify the main active sites, we synthesized cobalt particles embedded in carbon structures in absence of a sulphur source (Co@CNT) and evaluated its performance for MOR. The material characterization shows that adding sulphur during pyrolysis enhances the surface area, pore size and lattice defect. In addition, the morphology changes from hemi-spherical particles to nanowires, that significantly improves the electrochemical properties. The current density of N,S–Co@CNT is exceptionally higher (5.5 times) and the onset potential of MOR is shifted to lower potential when compared to Co@CNT. The enhanced activity, durability and stability of N,S–Co@CNT is ascribed to the unique hierarchical structure and surface properties.

Porous layered cobalt nanocrystal/nitrogen-doped carbon composites as efficient and CO-resistant electrocatalysts for methanol oxidation reaction

The development of active, stable and poison-resistant electrocatalysts for methanol oxidation reaction (MOR) has become a key challenge to improve the performance of direct methanol fuel cells (DMFCs). Herein, we report a simple strategy to prepare cobalt nanoscrystal/nitrogen-doped carbon (Co/N-C) composites as efficient and carbon monoxide (CO) resistant electrocatalysts for MOR. The Co/N-C composites are synthesized by the pyrolysis of porous CoCl2-polyaniline hydrogels. While CoCl2 is reduced to Co nanocrystals as active electrocatalyst for MOR, the polyaniline hydrogel is pyrolyzed to porous layered N-doped carbon that immobilize and protect Co nanocrystals, and also facilitate the mass and charge transfer through the electrolyte and electrode. After systematically exploring the preparation conditions of Co/N-C composites, we have found the optimal Co/N-C-1-500 (pyrolyzed at 500 °C) can achieve a high current density of 231 mA∙cm−2 at 0.8 V vs SCE for MOR in alkaline media. Meanwhile, the Co/N-C-1-500 catalyst presents a good durability and a high resistance to CO poisoning (93.5% retention of MOR activity), superior to the performance of Pt/C catalysts. With its high activity, good stability and superior resistance to CO poisoning, Co/N-C-1-500 is promising as a low-cost and efficient anode catalyst for DMFCs.

NiPd Supported on Mesostructured Silica Nanoparticle as Efficient Anode Electrocatalyst for Methanol Electrooxidation in Alkaline Media

The direct methanol fuel cell (DMFC) is a portable device and has the potential to produce 10 times higher energy density than lithium-ion rechargeable batteries. It is essential to build efficient methanol electrooxidation reaction electrocatalysts for DMFCs to achieve their practical application in future energy storage and conversion. A catalyst consisting of nickel–palladium supported onto mesostructured silica nanoparticles (NiPd–MSN) was synthesized by the wet impregnation method, while MSN was synthesized using the sol-gel method. MSN act as a catalyst support and has very good characteristics for practical support due to its large surface area (>1000 m2/g) and good chemical and mechanical stability. The microstructure and catalytic activity of the electrocatalysts were analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), Brunauer–Emmet–Teller (BET) theory, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and chronoamperometry (CA). XRD showed that the NiPd–MSN electrocatalysts had a high crystallinity of PdO and NiO, while FESEM displayed that NiPd was dispersed homogeneously onto the high surface area of MSN. In alkaline media, the catalytic activity toward the methanol oxidation reaction (MOR) of NiPd–MSN demonstrated the highest, which was 657.03 mA mg−1 more than the other electrocatalysts. After 3600 s of CA analysis at −0.2 V (vs. Ag/AgCl), the MOR mass activity of NiPd–MSN in alkaline media was retained at a higher mass activity of 190.8 mA mg−1 while the other electrocatalyst was significantly lower than that. This electrocatalyst is a promising anode material toward MOR in alkaline media.

Component-dependent activity of bimetallic PdCu and PdNi electrocatalysts for methanol oxidation reaction in alkaline media

In the work, the catalytic performance and reaction mechanism of methanol oxidation reaction(MOR) are studied for the bimetallic PdxCuy and PdxNiy catalysts in alkaline solution. The results reveal that the Pd1Ni1/C and Pd1Cu1/C bimetallic catalysts exhibit high catalytic activity 4.1 and 3.9 times higher than that of the commercial Pd/C catalyst. Combined with the X-ray diffraction (XRD), High-resolution transmission electron microscopy(HRTEM) and X-ray photoelectron spectroscopy (XPS) analysis, the charge transfer between Pd and Cu(or Ni) alters the electron density of Pd and enhances the anti-CO poisoning ability, which is confirmed by DFT (Density Functional Theory) calculations. The CO binding energy is weakened on various bimetallic surfaces compared with that on Pd(111), consistent with experimental results. A linear relationship exists between the CO binding energy and the catalytic activity on the bimetallic catalysts, indicating that the CO binding energy may be the potential descriptor for MOR in alkaline media.

Platinum supported on early transition metal carbides: Efficient electrocatalysts for methanol electro-oxidation reaction in alkaline electrolyte

Some classes of electrocatalysts based on Pt supported early transition metal carbides (TMCs) have shown promise for methanol oxidation reaction (MOR). To bridge the material gap, we studied some of the promising and new electrocatalysts for MOR. We synthesized 1%wt Pt/TMCs (TMCs of group IV (Ti and Zr), group V (V, Nb and Ta) and group VI (W)) via wet impregnation method as low loading electrocatalysts for MOR in alkaline media. The synthesized materials were characterized by X-ray diffraction (XRD), inductively coupled plasma-optical emission spectroscopy (ICP-OES), N2 physisorption using Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The activity of the electrocatalysts were elucidated for MOR in alkaline media via combination of experimental and theoretical methods. Among all the investigated electrocatalysts, Pt/NbC was found to have the highest specific activity (3.58 mA cmPt−2) while Pt/ZrC had the least (0.410 mA cmPt−2). Tafel slope measurements for Pt/TMC electrocatalysts with the exception of Pt/TiC varied from region of low potential to region of high potential and were 121.2 ± 11 mV dec−1 and 234 ± 10 mV dec−1 respectively, indicating change in limiting steps from C-H scission to CO poisoning. Density functional theory (DFT) calculations of the binding energies of H and CO on the Pt/TMC surfaces were correlated to their specific activity, and volcano-type relationships were discovered, which indicated that neither too weak nor too strong bond of H and CO on the electrocatalyst surfaces were favorable for high activity during MOR. Finally, a feasible reaction mechanism for Pt/TMC electrocatalysts in MOR was proposed based on the experimental and theoretical results.

Platinum nanoparticles coated by graphene layers: A low-metal loading catalyst for methanol oxidation in alkaline media

Platinum catalysts play a major role in the large scale commercialization of direct methanol fuel cells (DMFC). Here, we present a procedure to create a nanostructural graphene-platinum (GrPt) composite containing a small amount (5.3 wt%) of platinum nanoparticles coated with at least four layers of graphene. The composite, as GrPt ink, was deposited on a glassy carbon electrode and its electrocatalytic activity in a methanol oxidation reaction (MOR) was evaluated in a 1 M CH3OH/1 M NaOH solution. The results indicated an enhanced catalytic performance of GrPt towards MOR in alkaline media compared with the Pt/C material. Electron energy-loss spectroscopy and X-ray photoelectron spectroscopy (recorded before and after the electrochemical assays) were employed to analyze the changes in the chemical composition of the nanomaterial and to explain the transformations that took place at the electrode surface. Our findings suggest that growing of graphene on platinum nanoparticles improve the catalytic performance of platinum-graphene composites towards MOR in alkaline media.

Photo-electro synergistic catalysis: Can Pd be active for methanol electrooxidation in acidic medium?

Development of alternative Pt-free electrocatalyst for methanol oxidation reaction (MOR) in acidic medium remains a big challenge. As is reported, Pd is a good electrocatalyst for MOR in alkaline medium, but it is commonly recognized as inactive in acidic medium. Herein, we report an active Pd nanoparticles electrocatalyst for MOR in acidic medium although its catalytic activity is low. The photoexcitation of the plasmonic Pd nanoparticles leads to an MOR activity enhancement by a factor of 2 under visible light. Interestingly, the photogenerated electron-hole separation on nanosized TiO2 and the surface plasmon resonance effect of Pd nanoparticles on Pd/TiO2 heterostructure synergistically promote the photo-electrocatalytic activity of MOR under simulated solar light. The 17.9-fold activity enhancement of MOR in the presence of UV light indicates that the photogenerated electron-hole separation on TiO2 plays a crucial role in the photo-electro-synergistic methanol oxidation reaction. This remarkable light-driven activity enhancement of methanol oxidation reaction on Pd/TiO2 heterostructure suggests that the combination of plasmonic Pd nanoparticles and photogenerated electron-hole separation on TiO2 could provide a new strategy for the design and construction of energy conversion system.

The electrocatalytic performance of carbon ball supported RhCo alloy nanocrystals for the methanol oxidation reaction in alkaline media

Although both Pd and Rh fall into the Pd-group Pt-group elements (PPGEs), the electrocatalytic property of Rh nanocrystals for the methanol oxidation reaction (MOR) in alkaline media is rarely explored till now. In this work, we develop a surfactant-free co-precipitation/co-reduction method to synthesize the carbon ball supported RhCo alloy nanocrystals (RhCo/CB) nanohybrids with different Rh/Co atomic ratios and investigate their electrocatalytic acitvity for the MOR in alkaline media. Cyclic voltammetry and chronoamperometry measurements show Rh3Co1/CB nanohybrids have exceptional electrocatalytic activity and long-term stability for the MOR in alkaline media, much higher than commercial Pd/C and Pt/C electrocatalysts, demonstrating that Rh-based alloy nanocrystals may be highly promising Pt-alternative electrocatalyst for the MOR in alkaline media.

One-Pot Anchoring of Pd Nanoparticles on Nitrogen-Doped Carbon through Dopamine Self-Polymerization and Activity in the Electrocatalytic Methanol Oxidation Reaction.

Exploration of advanced electrocatalysts to promote the sluggish methanol oxidation reaction (MOR) is of vital importance for developing high efficiency and low-cost direct methanol fuel cells. Highly dispersed palladium nanoparticles (Pd NPs) anchored on a nitrogen-doped carbon support were fabricated using a facile one-pot dopamine self-polymerization mediated redox strategy, in which dopamine not only acted as a moderate reductant to induce the formation of Pd NPs during self-polymerization but was also the precursor of the nitrogen-doped carbon support for Pd. The synthesized hybrid features the following characteristics: 1) High dispersity of Pd NPs, which exposed a high abundance of active surfaces and sites for heterogeneous electrocatalysis; 2) metal-support interactions, which may affect the surface chemistry and electron distribution of active Pd NPs; 3) the Pd NPs were partially imbedded or encapsulated into the support, thus reducing the possible agglomeration of Pd NPs during cyclic measurements. The electrocatalyst with such favorable features provided higher mass activity (2.2 times that of commercial Pd/C) and better durability (reduced loss of activity during simulated frequent startup-shutdown operations) for the MOR in alkaline media.

Composition-Dependent Electrocatalytic Activity of Coral-Like Capping-Free PdCo Architectures toward Methanol Oxidation

Exploring advanced electrocatalysts to accelerate the sluggish methanol oxidation reaction (MOR) in the anode of direct methanol fuel cells is a promising route to alleviate the current challenges of fossil fuel exhaustion and environmental pollution. Herein, we develop capping-free PdCo alloys with a coral-like structure and use them as potential electrocatalysts to promote the MOR in alkaline media. A facile microwave-assisted wet chemical approach was established to prepare the unique PdCo architectures, in which no capping agent was employed. Through regulating the precursor ([PdCl4]2− and Co2+) proportion, the ratio of bimetals could be expediently tailored. HRTEM, SAED, XRD and XPS verified the formation of PdCo alloys with different Co abundances on surface. It was found that, together with morphology and crystallinity, the electrocatalytic activities of PdCo materials toward methanol oxidation were highly dependent on their compositions. Among synthesized PdCo structures, the best Pd56Co44 with a moderate Co enrichment on the alloy surface exhibited a mass activity dramatically 11.4 times higher than the pure Pd counterpart. This impressive activity of Pd56Co44 synergistically originated from the bifunctional effects and the electronic interactions between Pd and Co. In addition, the good performance durability of bimetallic PdCo was also demonstrated.

Communication—Acid-Treated Nickel-Rich Platinum–Nickel Alloys for Oxygen Reduction and Methanol Oxidation Reactions in Alkaline Media

We investigate the performance of platinum (Pt)–nickel (Ni) alloy catalysts with very low amounts of Pt, namely PtNi3, PtNi7, and PtNi15. Pre-treatment of the alloys was performed in bulk acid solution, and activities for the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) were measured in alkaline solution. Structural analysis suggests the removal of Ni only near the surface of the alloys. Pre-treated PtNi3 and PtNi7 are shown to be promising catalysts for both ORR and MOR in alkaline media.

Approach for Preparation of Bimetallic Palladium-Cobalt Catalysts with Enhanced Electrocatalytic Performance for Methanol Oxidation

A series of indium tin oxide (ITO) supported palladium-cobalt binary metallic anode catalysts were prepared and used in the methanol oxidation reaction (MOR), which is a key reaction in direct methanol fuel cells (DMFCs), providing superior fuel. The morphology, composition, and electrocatalytic performance of Pd-x-Co/ITO (x = 5, 10 and 15) catalysts were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), cyclic voltammetry (CV), and chronoamperometric techniques. For comparison, Pd-x/ITO (x = 5, 10 and 15) catalysts were also tested under the same conditions. Compared with pure Pd nanoparticles on ITO (Pd/ITO), due to the participation of Co as a support, the as-prepared Pd-10-Co/ITO catalyst exhibited a lower onset potential, enhanced electrocatalytic activity, and better durability in the MOR in alkaline media without the use of other oxidants. Moreover, Pd-10-Co/ITO can significantly contribute to cost reduction when used as an anode catalyst for DMFCs.

Palladium deposits spontaneously grown on nickel foam for electro-catalyzing methanol oxidation: Effect of precursors

Methanol, a high-energy substance, is widely used for green fuel cells. However, the sluggish electrochemical methanol oxidation reaction (MOR) on state-of-the-art catalysts still requires for exploring high-performance and low-cost materials to further promote the reaction kinetics at low overpotentials. Here we carried out the first electrocatalytic comparison study of two Ni foam-supported Pd nanomaterials (Pd-2-Ni and Pd-4-Ni, respectively), obtained through the spontaneous galvanic replacement of Ni with different palladic precursors ([PdCl4]2- and [PdCl6]2−, respectively), toward MOR. With replacement, Pd deposits with discrepant arrangements and coverages were grown on the porous Ni support. Compared to commercial Pd/C, both Pd-2-Ni and Pd-4-Ni exhibited better mass activity and catalytic durability for MOR in alkaline media. More interestingly, different palladic precursors made a significant effect on the catalytic performance of the Ni foam-supported Pd deposits. In Pd-4-Ni, the 2:1 stoichiometric replacement of Ni with [PdCl6]2− enabled the incompact arrangement of Pd structures, with more exposure of Ni atoms adjoined to Pd atoms on the catalytic interface compared to Pd-2-Ni. As a result, with the favorable Ni-neighbor-Pd regime and the higher utilization efficiency of Pd atoms, the synthesized Pd-4-Ni catalyst provided a mass activity of approximately 1.5 times higher than Pd-2-Ni toward MOR.

Room temperature synthesis of Pd–Cu nanoalloy catalyst with enhanced electrocatalytic activity for the methanol oxidation reaction

Bimetallic Pd–Cu nanoparticles with controllable size, composition and superior electrocatalytic activity towards methanol oxidation reaction (MOR) in alkaline media were synthesized by a facile room temperature soft chemical method. Pd–Cu nanoalloy catalysts (17–25nm) were prepared by templating Pd2+ and Cu2+ with ethylenediaminetetraacetic acid (EDTA) followed by controlled chemical reduction of metal–EDTA complex with hydrazine in highly basic medium at room temperature without any protection with an inert gas atmosphere. X-ray diffraction pattern indicates that the particles have an alloy structure. FESEM, EDX, HRTEM and SAED results further support the formation of Pd–Cu nanoalloy. Compliance of the lattice spacing corresponding to (111) and (200) planes obtained from HRTEM and SAED results with XRD data confirms the formation of Pd–Cu nanoalloy at room temperature. By varying the Pd2+/Cu2+ molar ratio the compositions of these alloy NPs can be easily adjusted. The amount of Cu present in the Pd–Cu nanoalloy plays a key role on the catalytic activity for MOR in alkaline media. Upon increase in concentration of Cu in the Pd–Cu nanoalloy, the catalytic activity towards MOR increases, reaches a maximum in Pd–Cu(3:1) nanoalloy and then decreases. The maximum mass activity of 659.4mAmg−1 of Pd obtained in the present work for the synthesized Pd–Cu(3:1) nanoalloy is much better than literature reported value. Multi-scan cyclic voltammetry and chronoamperometric studies confirm the electrocatalytic activity and stability of the synthesized electrode material. The present catalyst with low noble metal content promotes its practical use as anodes under alkaline conditions in direct methanol fuel cells (DMFC).

Novel-Phase Structural High-Efficiency Anode Catalyst for Methanol Fuel Cells: α-(NiCu)3Pd Nanoalloy

An approach has been explored to highly improve the catalytic activity and stability for methanol oxidation reaction (MOR) by using dominant α-(NiCu)3Pd phase-structural NiCuPd nanoparticles (NPs) as anode catalysts. The NiCuPd alloy NPs are monodispersed with the diameter of ∼10 nm and have been prepared by the reduction of Pd(acac)2, Ni(acac)2, and Cu(acac)2 following alloying growth process. In the Ni–Cu–Pd alloy system, Ni atoms fused in Cu3Pd phase to form α-(NiCu)3Pd phase together with NiCuPd solid solution phase. As Ni concentration gradually enriched, the crystallinity of α-(NiCu)3Pd became higher, while its percentage decreased by one degree. Owing to the synergistic effect between components and facet atom arrangement, the catalytic activity and stability of NiCuPd NPs can be adjusted toward the MOR in alkaline media. The maximized crystallinity of α-(NiCu)3Pd results in the largest catalytic activity. Compared with commercial Pd/C with (111) facets, α-(NiCu)3Pd phase with (117) facets afforded...