Properties For Methanol Oxidation Research Articles

Heterointerface engineering of rhombic Rh nanosheets confined on MXene for efficient methanol oxidation

Although metallic rhodium (Rh) is regarded as a promising platinum-alternative anode catalyst of direct methanol fuel cell (DMFC), the conventional “particle-to-face” contact model between Rh and matrix largely limits the overall electrocatalytic performance due to their insufficient cooperative effects. Herein, we report a controllable and robust heterointerface engineering strategy for the bottom-up fabrication of rhombic Rh nanosheets in situ confined on Ti3C2Tx MXene nanolamellas (Rh NS/MXene) via a convenient stereoassembly process. This unique design concept gives the resulting 2D/2D Rh NS/MXene heterostructure intriguing textural features, including large accessible surface areas, strong “face-to-face” interfacial interactions, homogeneous Rh nanosheet distribution, ameliorative electronic structure, and high electronic conductivity. As a consequence, the as-prepared Rh NS/MXene nanoarchitectures exhibit exceptional electrocatalytic methanol oxidation properties in terms of a large electrochemically active surface area of 126.2 m2 g−1Rh, a high mass activity of 1056.9 mA mg−1Rh, and a long service life, which significantly outperform those of conventional particle-shaped Rh catalysts supported by carbon black, carbon nanotubes, reduced graphene oxide, and MXene matrixes as well as the commercial Pt nanoparticle/carbon black and Pd nanoparticle/carbon black catalysts with the same noble metal loading amount. Density functional theory calculations further demonstrate that the direct electronic interaction at the well-contacted 2D/2D heterointerfaces effectively enhances the adsorption energy of Rh nanosheets and induces a left shift of the d-band center, thereby making the Rh NS/MXene configuration suffer less from CO poisoning. This work highlights the importance of rational heterointerface design in the construction of advanced noble metal/MXene electrocatalysts, which may provide new avenues for developing the next-generation DMFC devices.

Immobilizing ultrafine PtRu alloy nanoparticles onto 3D interconnected MXene-graphene frameworks for highly efficient methanol oxidation

Although direct methanol fuel cell (DMFC) is regarded as a promising power source to establish green energy conversion system, its overall performance is largely limited by the slow methanol oxidation kinetics of current anode catalysts. Herein, we demonstrate a robust and facile bottom-up strategy for the controllable construction of ultrafine PtRu alloy nanoparticles immobilized onto three-dimensional (3D) interconnected Ti3C2Tx MXene-graphene frameworks (PtRu/MXene-G) through a co-assembly process. Interestingly, the utilization of 3D porous MXene-G matrix provides strong interfacial interactions with alloy nanocrystals and promotes the transportation of both reactant and electron during the electrocatalytic process, while the introduction of Ru atoms ameliorates the Pt electronic structure and generates plentiful hydroxyl species for the oxidative removal of CO byproducts. Working together, the resulting PtRu/MXene-G nanoarchitecture with an appropriate Pt/Ru atomic ratio exhibits exceptional methanol oxidation properties in terms of a large electrochemically active surface area of 101.8 m2 g−1, a high mass (specific) activity of 1779.5 mA mg−1 (1.75 mA cm−2), and good long-term stability, all of which are significantly superior to those of conventional Pt/carbon black, Pt/G, Pt/MXene, and Pt/MXene-G catalysts with an identical Pt usage.

One-step liquid-phase synthesis of platinum nanocatalysts supported on carbon fiber substrates and their electrochemical characterization

Highly dispersed Pt nanoparticles supported on polyacrylonitrile-based carbon fiber substrates were prepared using a one-step liquid-phase process. Nanoparticles were grown on the fiber surface via electric resistance heating of the substrate in ethanol solutions containing a platinum-based organometallic complex as the nanoparticle precursor. After the synthesis, Pt nanoparticles were formed on the surface in highly dispersed states. Electrochemical characterization of the Pt nanoparticles was conducted using the substrates directly after synthesis. The Pt nanoparticles were electrochemically active and exhibited superior methanol oxidation properties.

Anchoring Ultrasmall Pt Nanocrystals onto Carbon Nanohorn-Decorated 3D Graphene Networks to Boost Methanol Oxidation Reaction

The successful commercialization of the direct methanol fuel cell (DMFC) is inseparable from the development of advanced Pt-based anode catalysts with high electrocatalytic activity and acceptable manufacturing cost. Here, we present a robust bottom-up strategy to anchor ultrasmall Pt nanocrystals with an average diameter of only 2.3 nm onto carbon nanohorn-decorated three-dimensional (3D) graphene networks (Pt/CNH-G) through a controllable self-assembly process. The as-derived 3D Pt/CNH-G catalysts manifest a series of distinctive architectural advantages, such as interconnected porous frameworks, large accessible surface areas, plentiful active cones, highly dispersed Pt nanoparticles, and good electron conductivity. Consequently, the optimized Pt/CNH-G catalyst is endowed with exceptional methanol oxidation properties with a large electrochemical active surface area of 128.6 m2 g-1, a high mass activity of 1626.0 mA mg-1, and excellent long-term stability, which are significantly superior to those of conventional Pt catalysts supported by carbon black, carbon nanotube, carbon nanohorn, and graphene matrices.

Pt-O/Pt active sites and electrocatalytic properties for methanol oxidation enhanced dually by anatase/rutile TiO2 and BiOx

Understanding the details of how Pt-O/Pt active sites are boosted is essential for many catalytic reactions. Herein, different anatase/rutile (A/R) phase ratios of TiO2 nanoparticles (NPs) prepared by controlling calcination temperature (T), and irreversibly adsorbed Bi(III) are employed to dually improve the Pt-O/Pt active sites and their electrocatalytic activities. It is found that a T-dependent concave improvement trend is obtained on Pt/TiO2-T for the Pt-O/Pt active sites and electrocatalytic methanol oxidation rate. In the simultaneous presence of TiO2-T and BiOx, the electron-rich R(110) facet of TiO2-950 can promote the formation of bimetallic Bi-Pt sites, and the oxygen-acceptable Bi(III) is favorite for the electrochemical assembly of {Bi-Ox-Pt} active sites on the R(110) facet, further achieving a remarkable increase of 19.7-fold and 4.5-fold for the Pt-O/Pt active sites and electrocatalytic activity towards methanol oxidation compared with the case of bare Pt electrodes, respectively. The relationship between the Pt-O/Pt active sites and electrocatalytic properties is demonstrated, and the complete oxidation mechanism of methanol is proposed on BiOx-[Pt-TiO2-950] with reliable long-term durability. This study shows a new dually tuning strategy to maximize the utilization efficiency and anti-deactivated ability of Pt-based catalysts by TiO2-T and BiOx.

A 2D/2D heterojunction of ultrathin Pd nanosheet/MXene towards highly efficient methanol oxidation reaction: the significance of 2D material nanoarchitectonics.

Two-dimensional (2D) Pd nanosheet-based catalysts have recently garnered widespread attention due to their high atom utilization efficiency. However, their catalytic ability and structural stability still require significant enhancement before they can be widely applied. In this study, we presented the rational design and controllable fabrication of a novel 2D/2D heterojunction, which consists of ultrathin Pd nanosheets (NSs) grown on the Ti3C2Tx MXene surface (Pd NSs/MXene). This heterostructure was achieved through a robust and convenient stereo-assembly strategy. The newly developed Pd NSs/MXene heterojunction not only provides numerous exposed active Pd atoms with an optimized electronic structure but also enables an intimate Pd/MXene interfacial interaction, ensuring a stable hybrid configuration. Consequently, the resulting Pd NSs/MXene heterojunction exhibits exceptional methanol oxidation properties. It possesses a large electrochemically active surface area, high mass and specific activities, and a long operating life, which are significantly superior to those of traditional Pd nanoparticle/carbon and Pd nanosheet/carbon catalysts. Theoretical simulations further reveal strong electronic interactions between the Pd nanosheet and MXene, which dramatically enhance the adsorption energy of the Pd component and simultaneously lower its d-band center. As a result, the Pd NSs/MXene heterojunction is less susceptible to CO poisoning. This work introduces a new 2D/2D heterojunction based on MXene and noble metallic materials and holds significance for the development of other novel heterojunctions, particularly within the realm of 2D material nanoarchitectonics.

(Digital Presentation) Carbon Aerogel Platinum-Praseodymium Oxide Nanocatalyst for Methanol Oxidation in 0.5 M Sulfuric Acid

Electrooxidation of methanol is an essential topic in developing direct methanol fuel cells, and numerous catalyst materials have been studied for this application. 1–3 Among other materials, the platinum-based composite catalysts containing rare earth metal oxides on various support materials have shown promising properties for methanol oxidation and implementation for direct methanol fuel cells.1–3 In this study, platinum-praseodymium oxide nanocatalyst on carbon aerogel support for methanol oxidation was synthesized. The material was electrochemically characterized using rotating disk electrode, cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy methods. X-ray diffraction, specific surface area measurements, thermogravimetric analysis, and high-resolution scanning electron microscopy with energy dispersive X-ray analysis were used to determine the physical properties of the material.The catalyst was synthesized by depositing platinum4 on a pyrolyzed organic aerogel doped with Pr(NO3)3 5,6. Synthesized nanocatalyst material contained 21 wt% of Pt and 20 wt% of PrOx. This material has micro-mesoporous structure with surface area of 230 m2 g−1, micropore area of 70 m2 g−1, total pore volume of 0.62 cm3 g−1 and micropore volume of 0.032 cm3 g−1. Pt and PrOx particles were uniformly dispersed on the supporting carbon aerogel-derived material.Electrochemical measurements showed that the studied material has an electrochemically active surface area of 54 mPt 2 gPt −1, which is noticeably higher than that for commercial Pt-Vulcan catalyst (17 mPt 2 gPt −1) and comparable with similar composite catalyst materials containing rare earth metal oxides (from 45 mPt 2 gPt −1 up to 61 mPt 2 gPt −1).3 For methanol electrooxidation the synthesized material showed high current density peaks in both anodic (310 A gPt −1) and cathodic (240 A gPt −1) potential sweeps. These current densities are higher than measured for commercial Pt-Vulcan catalyst (for the peaks in both anodic (178 A gPt −1) and cathodic (167 A gPt −1) potential sweeps). Furthermore, the synthesized material demonstrated the ability of preserving higher catalytic activity (0.33 A gPt −1) than the commercial Pt-Vulcan catalyst (0.07 A gPt −1) after working on a fixed potential of ‒0.2 V vs RHE for an extended period of time (30 min). While these results outstand the catalytic activity of some similar catalyst materials containing praseodymium,1,7,8 higher current densities on both cathodic and anodic potential sweep have been measured with Pt-PrOx catalyst deposited on carbon black Vulcan XC-72R.3 These characteristics show good suitability of the developed nanocatalyst for methanol oxidation in direct methanol fuel cells.This study shows the potential of nanocatalysts containing rare earth metal oxides and catalyst on the carbon aerogel support for methanol electrooxidation. These materials could be further investigated for the electrooxidation for ethanol or other organic fuels. Acknowlegements This work was supported by the EU through the European Regional Development Fund TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011), the Estonian Energy Technology Program: SLOKT10209T “Nanomaterials – research and applications (NAMUR)” project 3.2.0304.12-0397and Personal Research Grant PRG676. References Z. Tang and G. Lu, J. Power Sources, 162, 1067–1072 (2006).P. Valk et al., J. Electrochem. Soc., 165, F315–F323 (2018).P. Valk et al., J. Electrochem. Soc., 166, F1062 (2019).C. Galeano et al., J. Am. Chem. Soc., 134, 20457–20465 (2012).K. Kreek, M. Kulp, M. Uibu, A. Mere, and M. Koel, Oil Shale, 31, 185–194 (2014).K. Kreek et al., J. Non-Cryst. Solids, 404, 43–48 (2014).A. O. Neto et al., J. Alloys Compd., 476, 288–291 (2009).L. Chen, J. Hu, and J. S. Foord, Phys. Status Solidi A, 209, 1792–1796 (2012).

Building 3D Interconnected MoS2 Nanosheet–Graphene Networks Decorated with Rh Nanoparticles for Boosted Methanol Oxidation Reaction

The development of direct methanol fuel cell technology is one of the important ways to establish green energy production and conversion systems, while its large-scale commercial applications are severely hindered by the high cost and insufficient performance of current Pt-based anode catalysts. Here, we report the design and construction of a novel non-Pt electrocatalyst made from three-dimensional (3D) interconnected MoS2 nanosheet–reduced graphene oxide networks decorated with ultrafine Rh nanoparticles (Rh/MoS2-RGO) via a controllable co-assembly strategy. With unique structural features such as large specific surface areas, 3D interweaving porous frameworks, uniform Rh distribution, and excellent electron conductivity, the optimized Rh/MoS2-RGO catalyst is endowed with boosted electrocatalytic methanol oxidation properties, including a large electrochemical active surface area of 95.5 m2 g–1, a high mass (specific) activity of 1502.0 mA mg–1 (1.57 mA cm–2), and robust long-term stability, all of which significantly outperform those of reference Rh/RGO, Rh/carbon black, Rh/MoS2, as well as commercial Pt/carbon black and Pd/carbon black catalysts with the same metal content.

Low-temperature N-anchored ordered Pt3Co intermetallic nanoparticles as electrocatalysts for methanol oxidation reaction.

To enhance nanocatalyst performance and durability for the methanol oxidation reaction (MOR) in a direct methanol fuel cell, small-sized (2.1 nm) and structurally ordered Pt3Co intermetallic nanoparticles are uniformly anchored onto nitrogen-doped carbon nanotubes (N-CNTs) via a low-temperature N-anchoring method, and the N-doping abilities of different N-containing reagents are compared. After investigating the microstructure of Pt3Co/N-CNTs and evaluating their catalytic activity for the MOR, the results show that N-doping facilitates the uniform loading of Pt3Co NPs and plays a crucial role in improving the electrocatalytic activity of Pt3Co NPs supported on CNTs. Pt3Co/N-CNT-M with melamine as the N dopant exhibits the highest MOR activity and stability among all N-CNT-supported Pt3Co NPs and Pt/N-CNT-M. Density functional theory calculations suggest that the doping of N enhances the binding energy of CNTs to Pt3Co NPs, and the MOR mechanism shows that the introduction of Co is the reason for the enhancement of MOR reaction kinetics. The excellent electrochemical performance of Pt3Co/N-CNT-M is mainly attributed to the synergistic effect of N and Pt3Co intermetallic nanoparticles. The combination of ordered alloy nanoparticles and high-performance carrier N-CNT-M described herein exhibits great potential for fuel cells and may provide an unequivocal direction for the optimization of catalyst performance.

Electrocatalytic Oxidation of Methanol over An Electrode with Ni‐MOF‐74 Catalyst

AbstractDeveloping non‐noble metal catalysts for methanol oxidation in fuel cells is of importance. In this work, Ni‐MOF‐74 was synthesized through a simple solvothermal method and fully characterized. The as‐made Ni‐MOF‐74 modified carbon paste electrode (Ni‐MOF‐74/CPE) was applied for methanol electrooxidation reaction in 0.1 M NaOH solution. Ni‐MOF‐74 had high electrochemical stability and exhibited good electrocatalytic property for methanol oxidation, a mechanism for the reaction was proposed, the current density increases impressively on Ni‐MOF‐74/CPE compared with carbon paste electrode, and a really high catalytic rate constant (kcat) of 8.1×105 cm3 ⋅ mol−1 ⋅ s−1 was obtained in this work. The given results indicate that Ni‐MOF‐74 can be a promising candidate of electrocatalysts for direct methanol fuel cells (DMFCs).

Atomic Fe sites doped two-dimensional (001) TiO2 nanosheets as an effective photo-response support in methanol electro-oxidation

The anode supports of direct methanol fuel cell (DMFC) directly affect the energy conversion efficiency between methanol fuel and electric energy. Semiconductor-based supports have nice photoelectric property for photo-assisted electrocatalytic methanol oxidation, making it be a kind of promising support of Pt. However, the rapid recombination of semiconductor photogenerated carriers limits the methanol oxidation ability of Pt. Herein, the two-dimensional (2D) (001) TiO2 nanosheets doped by a small amount of atomic iron were prepared by a reproducible impregnation method as the anode support to decrease the recombination rate. The atomic iron sites doped 2D (001) TiO2 nanosheets electrode has a high electrocatalytic performance for methanol oxidation under UV light-excitation, which is 2.7 times higher than that in dark and 4.8 times than that of non-doped electrode. The nice activities of atomic iron sites doped 2D (001) TiO2 nanosheets can be attributed to the introduction of atomic iron which are beneficial for the separation of photogeneration carriers and producing more photogenerated holes for the generation of strong oxidizing hydroxyl radicals (•OH). During the process of electrocatalytic methanol oxidation, •OH can not only promote the photocatalytic methanol oxidation, but also attenuate the inactivation of Pt poisoned by COads. These results provide a strategy to further ameliorate the photo-assisted electrocatalytic property for methanol oxidation.

Construction of three-dimensional hierarchical Pt/TiO2@C nanowires with enhanced methanol oxidation properties

Three-dimensional (3D) hierarchical Pt/TiO2@C core-shell nanowire networks with high surface area have been constructed via wet chemical approaches. The 3D TiO2 nanowire framework was in situ synthesized within a porous titanium foam by hydrothermal method followed by carbon coating and self-assembled growth of ultrathin Pt nanowires. Structural characterization indicates that single crystalline ultrathin Pt nanowires of 3–5 nm in diameter were vertically distributed on the anatase TiO2 nanowires covered with a 2–4 nm thin carbon layer. The 3D hierarchical Pt/TiO2@C nanostructure demonstrates evidently higher catalytic activities towards methanol oxidation than the commercial Pt/C catalyst. The catalytic current density of the hierarchical catalyst is 1.6 times as high as that of the commercial Pt/C, and the oxidation onset potential (0.35 V vs. Ag/AgCl) is more negative than the commercial one (0.46 V vs. Ag/AgCl). Synergistic effect between the ultrathin Pt nanowires and the TiO2@C core-shell nanostructure accounts for the enhanced catalytic properties, which can be determined by X-ray photoelectron spectroscopy (XPS) investigation. The obtained hierarchical Pt/TiO2@C nanowire networks promise great potential in producing anode catalysts for direct methanol fuel cells applications.

Controllable synthesis of grain boundary-enriched Pt nanoworms decorated on graphitic carbon nanosheets for ultrahigh methanol oxidation catalytic activity

A convenient and cost-effective approach is developed to produce ultrafine grain boundary-enriched Pt nanoworms grown on nitrogen-doped low-defect graphitic carbon nanosheets, which possess excellent electrocatalytic properties for methanol oxidation. • Controllable synthesis of 1D ultrafine Pt nanoworms is achieved. • Electronic-structure engineering endows the catalyst with numerous active sites. • The catalyst shows a high mass activity of 1949 mA mg −1 for methanol oxidation. • DFT calculations reveal the underlying catalytic mechanisms of the hybrid system. Although one-dimensional Pt nanocrystals have long been regarded as ideal electrode catalysts for fuel cells, the synthetic techniques commonly involve the use of various complicated templates or surfactants, which have largely hampered their large-scale industrial application. Herein, we present a convenient and cost-effective approach to the stereoassembly of quasi-one-dimensional grain boundary-enriched Pt nanoworms on nitrogen-doped low-defect graphitic carbon nanosheets (Pt NWs/NL-CNS). Benefiting from its numerous catalytically active grain boundaries as well as optimized electronic structure, the as-derived Pt NWs/NL-CNS catalyst possesses exceptionally good electrocatalytic properties for methanol oxidation, including an ultrahigh mass activity of 1949.5 mA mg −1 , reliable long-term durability, and strong poison tolerance, affording one of the most active Pt-based electrocatalysts for methanol oxidation reaction. Density functional theory calculation further reveals that the formation of worm-shape Pt morphology is attributed to the modified electronic structure as well as controllable defect density of the carbon matrix, which could also weaken the adsorption ability of Pt towards CO molecule and meanwhile synergistically promotes the catalytic reaction kinetics.

Preparation of flexible composite electrode with bacterial cellulose (BC)-derived carbon aerogel supported low loaded NiS for methanol electrocatalytic oxidation

In this study, carbon aerogel (CA) were obtained by inexpensive bacterial cellulose (BC) hydrogel freeze-dried and carbonized under N2 atmosphere. Then nickel sulfide (NiS)/CA composite aerogel electrodes with different contents were successfully prepared by a one-step solvothermal method. The morphology, phases and surface electronic state of these electrodes were characterized by SEM/TEM, XRD and XPS, respectively, and their electrocatalytical properties for methanol oxidation were investigated by cyclic voltammetry (CV) in the alkaline media of methanol. The NiS particles dispersed uniformly on CA, and the obtained material maintained the reticulated porous structure of BC. The methanol oxidation peak current density of CNS-0.5 at 0.8 V reached 43 mA/cm2 (263 mA/mg). After 1000 cycles, the peak current density retained 92% of the initial state. The composite electrode has good catalytic activity and good cycle performance for methanol catalysis. Nickel sulfide with high crystallinity transforms to nickel oxide with low crystallinity after a long cycle test, which results in excellent cycle performance of the composite. NiS/CA electrodes have the potential for application in portable or wearable devices.

Phase-transformation of hexagonal Cu2S microplates to nanoparticle-confined Cu2O microplates at low temperatures and their electro-catalytic property for methanol oxidation

The direct phase transformation of hexagonal Cu2S microplates to those that are S-included Cu2O was induced by low-temperature annealing at 200 °C under ambient conditions. The Cu2O microplates showed a nanoparticle-confined structure, which continued to have the hexagonal framework of the original Cu2S microplates. The compositional distributions, sizes, structures, and optical properties of the synthesized Cu2S and S-included Cu2O microplates were characterized. The S-included Cu2O microplates prepared via low-temperature annealing at 200 °C for 12 h (Cu2S-Cu2O-12 h), 24 h (Cu2S-Cu2O-24 h), and 48 h (Cu2S-Cu2O-48 h) showed electro-catalytic activities for methanol oxidation. The Cu2S-Cu2O-24 h microplates showed the best electro-catalytic activity and long-term stability.

Formation of Bi-Containing sea urchin-like Pt nanoparticles induced by the addition of bismuth element and their enhanced electrocatalytic properties for methanol oxidation

A facile method to synthesize Bi-containing sea urchin-like Pt nanoparticles is demonstrated. The morphology and chemical composition of the prepared Bi-containing sea urchin-like Pt nanoparticles were characterized using scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Electrochemical studies of the oxidation of methanol in an acidic medium using the Bi-containing sea urchin-like Pt nanoparticles were performed. The prepared nanoparticles exhibited enhanced electrocatalytic activity for methanol oxidation with a seven-fold higher oxidation current density and a more negative onset potential than commercial Pt/C (Pt 20%). Moreover, the current density of the Bi-containing sea urchin-like Pt nanoparticle/C catalysts was high even after 900 s of continuous electrocatalysis at 0.56 V. The synthesized Bi-containing sea urchin-like Pt nanoparticles should find attractive applications in various fields, such as fuel cells, sensors, and eletro- or organic catalysis.

Enhanced electrocatalytic methanol oxidation properties by photo-assisted Fe2O3 nanoplates

Abstract In this paper, visible-light-driven two-dimensional (2D) Fe2O3 nanoplates with exposed (001) facets were first adopted to act as Pt support for photo-assisted electrocatalytic methanol oxidation. Under simulated solar light and visible light illumination Pt-2D Fe2O3 nanoplates displayed 2.32 and 1.30 times higher electrocatalytic activities for methanol oxidation than in dark condition, respectively. Besides, 2D Fe2O3 nanoplates owns much better electrocatalytic activities for methanol oxidation than Fe2O3 particles whether in dark, visible light or simulated solar light illumination. The nice photo-assisted electrocatalytic methanol oxidation activities of Pt-2D Fe2O3 nanoplates can be attributed to 2D structure enhanced the oxidation activities of photogenerated holes to oxidize OH− to hydroxyl radical (·OH) as well as its large specific surface area. Our experimental results suggest that photo-assisted and two-dimensional strategy of semiconductors are promising ways to further improve the electrocatalytic activities for methanol oxidation in DMFCs.

Site-selectively Pt-decorated PdPt bimetallic nanosheets characterized by electrocatalytic property for methanol oxidation

In this work, a facile synthetic method for site-selectively Pt-decorated PdPt bimetallic nanosheets (S-Pt-PdPtBN) has been described. The size, structure, and composition distribution of the synthesized S-Pt-PdPtBN were determined by transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The electrocatalytic activity of these bimetallic nanosheets was examined for the oxidation of methanol in an acidic solution. The electrochemically active surface area (ECSA) of S-Pt-PdPtBN was 0.842 cm2. This value is slightly lower than the ECSA (1.012 cm2) of the commercial Pt/C (Alpha, Pt 10%) electrode. Interestingly, even though the ECSA of the S-Pt-PdPtBN/C was smaller than that of the commercial Pt/C, the forward peak current density of the former (2.95 mA cm−2) was ca. 1.5 times higher than that of the latter (2.05 mA cm−2). Moreover, the current density of the S-Pt-PdPtBN/C catalysts was high even after 800 s of continuous electrocatalysis at 0.5 V. This current density is six times that of commercial Pt/C catalysts. Thus, the synthesized S-Pt-PdPtBN exhibited significantly enhanced electrocatalytic activity and better stability than the commercial Pt/C catalyst for methanol oxidation.

Synthesis of Nanostructured Bimetallic Catalysts for Electrochemical Applications

Bimetallic nanostructures of specific compositions and enclosed by certain facets can significantly alter their physical and chemical properties and thus provide the opportunities to tailor them for particular electrochemical applications. Despite significant progress in recent years, it is still a grand challenge to control the spatial distribution of elements and surface structure of bimetallic nanoparticles. Thus, it remains very difficult to understand the properties of bimetallic nanoparticles, and even more challenging to overcome the formidable barriers to the rational design of bimetallic nanoparticles with the desired performance. This research focuses on the development of seed-mediated synthesis in solution aiming to precisely control the atomic arrangement in the bimetallic catalysts to establish the structure-composition-property relationship for electrocatalytic applications. In seed-mediated synthesis, the seeds can be preformed or in situ formed as a primary nanoscale substrate, followed by reducing secondary precursors to form bimetallic or multimetallic nanocatalysts. By controlling the shape of the seeds and reduction kinetics, well-defined bimetallic and multimetallic nanostructures can be obtained. In this work, CuPt and CuPtRu nanomaterials will be used as an example to demonstrate how changes of spatial atomic arrangement in the nanostructures influence their electrocatalytic properties for methanol oxidation. Fine tuning and mechanistic study of these synthetic strategies provide us fundamental understanding for precise control of bimetallic nanostructures to tackle problems in materials chemistry and open up the possibility for rational design and synthesis of future complex nanoarchitectures towards electrochemical applications.

Catalysis for Low-Temperature Fuel Cells

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