One-step synthesis of porous bimetallic PtCu nanocrystals with high electrocatalytic activity for methanol oxidation reaction

Unraveling ultrasonic assisted aqueous-phase one-step synthesis of porous PtPdCu nanodendrites for methanol oxidation with a CO-poisoning tolerance

The tailored design of tri-metallic Pt-based porous nanodendrites (PNDs) is crucial for green energy production technologies, ascribed to their fancy features, great surface areas, accessible active sites, and stability against aggregation. However, their aqueous-phase one-step synthesis at room temperature remains a daunting challenge. Herein, we present a facile, green, and template-free approach for the one-step synthesis of PtPdCu PNDs by ultrasonication of an aqueous solution of metal salts and Pluronic F127 at 25 ℃, based on natural isolation among nucleation and growth step driven by the disparate reduction kinetics of the metals and acoustic cavitation mechanism of ultrasonic waves. The resultant PtPdCu PNDs formed in a spatial nanodendritic shape with a dense array of branches, open corners, interconnected pores, high surface area (46.9 m²/g), and high Cu content (21 %). The methanol oxidation reaction (MOR) mass activity of PtPdCu PNDs (3.66 mA/µg_Pt) is 1.45, 2.73, and 2.83 times higher than those of PtPd PNDs, PtCu PNDs, and commercial Pt/C, respectively based on equivalent Pt mass, which is superior to previous PtPdCu catalysts reported elsewhere, besides a superior durability and CO-poisoning tolerance. This study may pave the way for the controlled fabrication of ternary Pt-based PNDs for various electrocatalytic applications.

Pt-Based Nanostructures for Electrochemical Oxidation of CO: Unveiling the Effect of Shapes and Electrolytes

Direct alcohol fuel cells are deemed as green and sustainable energy resources; however, CO-poisoning of Pt-based catalysts is a critical barrier to their commercialization. Thus, investigation of the electrochemical CO oxidation activity (COOxid) of Pt-based catalyst over pH ranges as a function of Pt-shape is necessary and is not yet reported. Herein, porous Pt nanodendrites (Pt NDs) were synthesized via the ultrasonic irradiation method, and its CO oxidation performance was benchmarked in different electrolytes relative to 1-D Pt chains nanostructure (Pt NCs) and commercial Pt/C catalyst under the same condition. This is a trial to confirm the effect of the size and shape of Pt as well as the pH of electrolytes on the COOxid. The COOxid activity and durability of Pt NDs are substantially superior to Pt NCs and Pt/C in HClO4, KOH, and NaHCO3 electrolytes, respectively, owing to the porous branched structure with a high surface area, which maximizes Pt utilization. Notably, the COOxid performance of Pt NPs in HClO4 is higher than that in NaHCO3, and KOH under the same reaction conditions. This study may open the way for understanding the COOxid activities of Pt-based catalysts and avoiding CO-poisoning in fuel cells.

Pd/Ni-metal-organic framework-derived porous carbon nanosheets for efficient CO oxidation over a wide pH range

Metal nanocrystal ornamented metal-organic frameworks (MOFs) are of particular interest in multidisciplinary applications; however, their electrocatalytic CO oxidation performance over wide pH ranges is not yet reported. Herein, Ni-MOF-derived hierarchical porous carbon nanosheets (Ni-MOF/PC) with abundant Ni-N x sites decorated with Pd nanocrystals (Pd/Ni-MOF/PC) were synthesized by microwave-irradiation (MW-I) followed by annealing at 900 °C and subsequent etching of Ni-MOF/C prior to Pd deposition. The fabrication mechanism comprises the generation of self-reduced reducing gases from triethylamine during the annealing and selective chemical etching of Ni, thereby facilitating the reduction of Ni-anchored MOF and Pd nanocrystal deposition with the aid of ethylene glycol and MW-I to yield Pd/Ni-N x enriched MOF/PC. The synthetic strategies endear the Pd/Ni-MOF/PC with unique physicochemical merits: abundant defects, interconnected pores, high electrical conductivity, high surface area, Ni-deficient but more active sites for Pd/Ni-N x in porous carbon nanosheets, and synergism. These merits endowed the CO oxidation activity and stability on Pd/Ni-MOF/PC substantially than those of Pd/Ni-MOF/C and Pd/C catalysts in wide pH conditions (i.e., KOH, HClO4, and NaHCO3). The CO oxidation activity study reveals the utilization of MOF/PC with metal nanocrystals (Pd/Ni) in CO oxidation catalysis.

Cerium functionalized graphene nano-structures and their applications; A review

Graphene-based nanomaterials with remarkable properties, such as good biocompatibility, strong mechanical strength, and outstanding electrical conductivity, have dramatically shown excellent potential in various applications. Increasing surface area and porosity percentage, improvement of adsorption capacities, reduction of adsorption energy barrier, and also prevention of agglomeration of graphene layers are the main advantages of functionalized graphene nanocomposites. On the other hand, Cerium nanostructures with remarkable properties have received a great deal of attention in a wide range of fields; however, in some cases low conductivity limits their application in different applications. Therefore, the combination of cerium structures and graphene networks has been widely invesitaged to improve properties of the composite. In order to have a comprehensive information of these nanonetworks, this research reviews the recent developments in cerium functionalized graphene derivatives (graphene oxide (GO), reduced graphene oxide (RGO), and graphene quantum dot (GQD) and their industrial applications. The applications of functionalized graphene derivatives have also been successfully summarized. This systematic review study of graphene networks decorated with different structure of Cerium have potential to pave the way for scientific research not only in field of material science but also in fluorescent sensing, electrochemical sensing, supercapacitors, and catalyst as a new candidate.

Regulating the lattice strain of platinum–copper catalysts for enhancing collaborative electrocatalysis

PtnCu100−n alloy nanostellates showed the high catalytic activity for both the oxygen reduction and alcohol oxidation reactions.

Evolution of PtCu tripod nanocrystals to dendritic triangular nanocrystals and study of the electrochemical performance to alcohol electrooxidation

In the field of catalysis, the design and construction of nanomaterials is an efficient way to optimize the catalytic activity of catalysts. This study presents the synthesis of PtCu tripod nanocrystals with branching structures and high purity prepared using a simple hydrothermal method. The dendritic PtCu triangular nanocrystals were successfully synthesized by regulating the amount of I^- ions to achieve different degrees of branching on PtCu nanocrystals, and the process was systematically studied and analyzed. Meanwhile, dumbbell nanocrystals of PtCu were successfully synthesized through slight adjustments to synthesis conditions. In electrochemical tests, the obtained dendritic PtCu triangular nanocrystals exhibited prominent electrocatalytic activity and long-term stability for ethylene glycol, methanol, and ethanol oxidation reactions due to the unique nanostructures as well as alloyed virtue, and were much better than commercial Pt/C. In addition, this study provides a general strategy for designing novel branched Pt-based nanomaterials with high electrocatalytic performance.

Tailoring the defects of sub-100 nm multipodal titanium nitride/oxynitride nanotubes for efficient water splitting performance

Deciphering the photocatalytic-defect relationship of photoanodes can pave the way towards the rational design for high-performance solar energy conversion. Herein, we rationally designed uniform and aligned ultrathin sub-100 nm multipodal titanium nitride/oxynitride nanotubes (TiON _x NTs) (x = 2, 4, and 6 h) via the anodic oxidation of Ti-foil in a formamide-based electrolyte followed by annealing under ammonia gas for different durations. XPS, XPS imaging, Auger electron spectra, and positron annihilation spectroscopy disclosed that the high nitridation rate induced the generation of a mixture of Ti-nitride and oxynitride with various vacancy-type defects, including monovacancies, vacancy clusters, and a few voids inside TiO _x NTs. These defects decreased the bandgap energy to 2.4 eV, increased visible-light response, and enhanced the incident photon-to-current collection efficiency (IPCE) and the photocurrent density of TiON _x NTs by nearly 8 times compared with TiO₂NTs, besides a quick carrier diffusion at the nanotube/electrolyte interface. The water-splitting performance of sub-100 nm TiON₆NT multipodal nanotubes was superior to the long compacted TiON _x NTs with different lengths and TiO₂ nanoparticles. Thus, the optimization of the nitridation rate tailors the defect concentration, thereby achieving the highest solar conversion efficiency.

A universal approach for the synthesis of mesoporous gold, palladium and platinum films for applications in electrocatalysis

High-surface-area mesoporous materials expose abundant functional sites for improved performance in applications such as gas storage/separation, catalysis, and sensing. Recently, soft templates composed of amphiphilic surfactants and block copolymers have been used to introduce mesoporosity in various materials, including metals, metal oxides and carbonaceous compounds. In particular, mesoporous metals are attractive in electrocatalysis because their porous networks expose numerous unsaturated atoms on high-index facets that are highly active in catalysis. In this protocol, we describe how to create mesoporous metal films composed of gold, palladium, or platinum using block copolymer micelle templates. The amphiphilic block copolymer micelles are the sacrificial templates and generate uniform structures with tunable pore sizes in electrodeposited metal films. The procedure describes the electrodeposition in detail, including parameters such as micelle diameters, deposition potentials, and deposition times to ensure reproducibility. The micelle diameters can be controlled by swelling the micelles with different solvent mixtures or by using block copolymer micelles with different molecular weights. The deposition potentials and deposition times allow further control of the mesoporous structure and its thickness, respectively. Procedures for example applications are included: glucose oxidation, ethanol oxidation and methanol oxidation reactions. The synthetic methods for preparation of mesoporous metal films will take ~4 h; the subsequent electrochemical tests will take ~5 h for glucose sensing and ~3 h for alcohol oxidation reaction.

Unveiling One-Pot Template-Free Fabrication of Exquisite Multidimensional PtNi Multicube Nanoarchitectonics for the Efficient Electrochemical Oxidation of Ethanol and Methanol with a Great Tolerance for CO

Multidimensional bimetallic Pt-based nanoarchitectonics are highly promising in electrochemical energy conversion technologies because of their fancy structural merits and accessible active sites; however, hitherto their precise template-free fabrication remains a great challenge. We report a template-free solvothermal one-pot approach for the rational design of cocentric PtNi multicube nanoarchitectonics via adjusting the oleylamine/oleic acid ratio with curcumin. The obtained multidimensional PtNi multicubes comprise multiple small interlace-stacked nanocube subunits assembled in spatially porous branched nanoarchitectonics and bound by high-index facets. The synthetic mechanism is driven by spontaneous isolation among prompt nucleation and oriented attachment epitaxial growth. These inimitable architectural and compositional merits of PtNi multicubes endowed the ethanol oxidation mass and specific activity by 5.6 and 9.03 times than the Pt/C catalyst, respectively, along with the enhancement of methanol oxidation mass activity by 2.3 times. Moreover, PtNi multicubes showed superior durability and a higher tolerance for CO poisoning than the Pt/C catalyst. This work may pave the way for tailored preparation of Pt-based nanoarchitectonics for myriad catalytic reactions.

Cubic-like PtCuRu Nanocrystals with High Activity and Stability for Methanol Electro-oxidation

Porous cubic-like PtCu and PtCuRu nanocrystals, which had a similar porous three-dimensional structure, were successfully prepared via the one-pot method. During the growth of the nanocrystals, cetyltrimethylammonium chloride and ascorbic acid were employed as the structure director and assistant reducing agent, respectively. The structure and possible formation of the nanocrystals were investigated. It is worth mentioning that the PtCuRu nanocrystals demonstrated a much better methanol electro-oxidation ability and ultrahigh stability, which displayed 3.4- and 3-fold higher specific and mass activity, respectively, than the commercial Pt/C. The advantage of PtCuRu nanocrystals was possibly ascribed to the synergistic effect of Cu and the porous structure and, more importantly, the presence of Ru that could more efficiently eliminate the harmful intermediates.

Segmentation and Re-encapsulation of Porous PtCu Nanoparticles by Generated Carbon Shell for Enhanced Ethylene Glycol Oxidation and Oxygen-Reduction Reaction

Hierarchical porous carbon-encapsulated ultrasmall PtCu (UsPtCu@C) nanoparticles (NPs) were constructed based on segmentation and re-encapsulation of porous PtCu NPs by using glucose as a green biomass carbon source. The synergistic electronic effect from the bimetallic elements can enhance the catalytic activity by adjusting the surface electronic structure of Pt. Most importantly, the generated porous carbon shell provided a large contact surface area, excellent electrical conductivity, and structural stability, and the ultrasmall PtCu NPs exhibited an increased electrochemical performance compared with their PtCu matrix because of the exposure of more catalytically active centers. This synergistic relationship between the components resulted in enhanced catalytic activity and better stability of the obtained UsPtCu@C for ethylene glycol oxidation reaction and the oxygen-reduction reaction in alkaline electrolyte, which was higher than the PtCu NPs and commercial Pt/C (20 wt % Pt on Vulcan XC-72). The electrochemically active surface areas of the UsPtCu@C, PtCu NPs, and commercial Pt/C were calculated to be approximately 230.2, 32.8, and 64.0 m²/g_Pt, respectively; the mass activity of the UsPtCu@C for the ethylene glycol oxidation reaction was 8.5 A/mg_Pt, which was 14.2 and 8.5 times that of PtCu NPs and commercial Pt/C, respectively. The specific activity of UsPtCu@C was 3.7 mA/cm_pt², which was 2.1 and 2.3 times that of PtCu NPs and commercial Pt/C, respectively. The onset potential (E_on-set) of UsPtCu@C for the oxygen-reduction reaction was 0.96 V (vs reversible hydrogen electrode, RHE), which was 110 and 60 mV higher than PtCu and commercial Pt/C, respectively. The half-wave potentials (E_1/2) of UsPtCu@C, PtCu, and Pt/C were 0.88, 0.56, and 0.82 V (vs RHE), respectively, which indicated that the UsPtCu@C catalyst had an excellent bifunctional electrocatalytic activity.

Salt-Templated Platinum-Copper Porous Macrobeams for Ethanol Oxidation

Platinum nanomaterials provide an excellent catalytic activity for diverse applications and given its high cost, platinum alloys and bi-metallic nanomaterials with transition metals are appealing for low cost and catalytic specificity. Here the synthesis of hierarchically porous Pt–Cu macrobeams and macrotubes templated from Magnus’s salt derivative needles is demonstrated. The metal composition was controlled through the combination of [PtCl4]2− with [Pt(NH3)4]2+ and [Cu(NH3)4]2+ ions in different ratios to form salt needle templates. Polycrystalline Pt–Cu porous macrotubes and macrobeams 10’ s–100’ s μm long with square cross-sections were formed through chemical reduction with dimethylamine borane (DMAB) and NaBH4, respectively. Specific capacitance as high as 20.7 F/g was demonstrated with cyclic voltammetry. For macrotubes and macrobeams synthesized from Pt2−:Pt2+:Cu2+ salt ratios of 1:1:0, 2:1:1, 3:1:2, and 1:0:1, DMAB reduced 3:1:2 macrotubes demonstrated the highest ethanol oxidation peak currents of 12.0 A/g at 0.5 mV/s and is attributed to the combination of a highly porous structure and platinum enriched surface. Salt templates with electrochemical reduction are suggested as a rapid, scalable, and tunable platform to achieve a wide range of 3-dimensional porous metal, alloy, and multi-metallic nanomaterials for catalysis, sensor, and energy storage applications.

Convenient Synthesis of 3D Fluffy PtPd Nanocorals Loaded on 2D h-BN Supports as Highly Efficient and Stable Electrocatalysts for Alcohol Oxidation Reaction

Fuel cells hold great promise for clean and sustainable energy, whereas their widespread commercialization strongly depends on the development of highly efficient and stable electrocatalysts. Herein, three-dimensional fluffy PtPd nanocorals (NCs) loaded on two-dimensional (2D) hexagonal boron nitride (h-BN) supports were successfully achieved by a simple one-step strategy based on ultraviolet (UV) laser-excited photochemical reaction. As for alcohol oxidation reaction, the h-BN/PtPd NCs with unique nanoporous surface provide more enhanced electrocatalytic performances than many previous nanocatalysts, owing to abundant active sites and plentiful charge-transfer channels formed on high electrode-electrolyte contact area. Especially, the mass activity of h-BN/PtPd NCs is about 962.8 mA mg_PtPd ^-1 in methanol oxidation reaction in alkaline solution, which can be maintained at ∼274.9 mA mg_PtPd ^-1 (28.6% of the initial one) even after a 5 × 10⁴ s durability test. The present work not only offers an advanced electrocatalyst for long-term fuel cells but also provides a versatile route for construction of complex metallic nanocomposites on 2D supports, holding great potential for diverse energy-related applications.

Unraveling template-free fabrication of carbon nitride nanorods codoped with Pt and Pd for efficient electrochemical and photoelectrochemical carbon monoxide oxidation at room temperature

The tailored synthesis of carbon nitrides (CNs) is of particular interest in multidisciplinary catalytic applications. However, their fabrication in the form of one-dimensional (1D) nanorods for electrocatalytic carbon monoxide (CO) oxidation is not hitherto reported. Herein, a facile roadmap is presented for the rational design of Pt- and Pd-codoped CN (PtPd/CNs) nanorods via protonation of melamine in an ethylene glycol solution containing Pt and Pd precursors using NaNO3 and HCl and subsequent annealing. The protonation induces the polymerization of melamine to melon nanosheets that consequently roll up to CN nanorods. This tailored the prompt high mass production of uniform 1D CN nanorods (94 ± 2 nm) with a high surface area (155.2 m2 g-1) and they were atomically codoped with Pt and Pd (1.5 wt%) without a template and/or multiple complicated steps. The electrocatalytic CO oxidation activity of PtPd/CNs is 2.01 and 23.41 times greater than that of the commercial Pt/C catalyst and metal-free CNs, respectively, at room temperature. Meanwhile, the UV-vis light irradiation enhanced the CO oxidation activity of PtPd/CNs nanorods by 1.48 fold compared to that in the dark, emanated from the coupling between the drastic inbuilt catalytic merits of PtPd and the inimitable physicochemical properties of CNs. The presented study may pave the way for using CN-based materials in gas conversion reactions.

Monodispersed bimetallic platinum-copper alloy nanospheres as efficient catalysts for ethylene glycol electrooxidation

Designing and fabricating highly active and efficient catalysts are of vital importance for the practical applications of direct ethylene glycol fuel cells (DEGFCs). In this study, we employ a feasible one-pot synthetic method to construct highly monodispersed PtCu nanospheres (NSs) as high-efficiency anode electrocatalysts for DEGFCs. Interestingly, the optimized carbon supported Pt₁Cu₁ NSs can display the highest mass activity of 2146.9 mA mg^-1 in 1 M KOH + 1 M EG solution under the scan rate of 50 mV s^-1, which is 1.9 times higher than that of commercial Pt/C catalysts. This is ascribed to the favorable electronic effect between Pt and Cu, which is beneficial for ethylene glycol oxidation reaction (EGOR) in fuel cells. Meanwhile, such monodispersed Pt₁Cu₁ NSs can also exhibit excellent durability, where the Pt₁Cu₁ catalyst retains 62.6% of the initial value after the cyclic voltammetry of 500 cycles. This work not only provides a significant approach for designing catalysts for fuel cells, but also constructs a novel class of active and stable electrocatalysts for EGOR.

Rational Synthesis of Porous Graphitic-like Carbon Nitride Nanotubes Codoped with Au and Pd as an Efficient Catalyst for Carbon Monoxide Oxidation

The precise fabrication of efficient catalysts for CO oxidation is of particular interest in a wide range of industrial and environmental applications. Herein, a scalable method is presented for the controlled synthesis of graphitic-like porous carbon nitride nanotubes (gC₃N₄NTs) codoped with Au and Pd (Au/Pd/gC₃N₄NTs) as efficient catalysts for carbon monoxide (CO) conversion. This includes the activation of melamine with nitric acid in the presence of ethylene glycol and metal precursors followed by consecutive polymerization and carbonization. This drives the formation of porous one-dimensional gC₃N₄NT with an outstanding surface area of (320.6 m² g^-1) and an atomic-level distribution of Au and Pd. Intriguingly, the CO conversion efficiency of Au/Pd/gC₃N₄NTs was substantially greater than that for gC₃N₄NTs. The approach thus presented may provide new avenues for the utilization of gC₃N₄ doped with multiple metal-based catalysts for CO conversion reactions which had been rarely reported before.

Uric acid supported one-pot solvothermal fabrication of rhombic-like Pt35Cu65 hollow nanocages for highly efficient and stable electrocatalysis

High activity and good durability of electrocatalysts are of significance in practical applications of fuel cells. Among them, multi-component metallic hollow nanocages/nanoframes show great potential as advanced catalysts because of their highly open structures, large surface area and good stability. Herein, we report a general uric acid-mediated solvothermal method for shape-controlled synthesis of rhombic-like Pt₃₅Cu₆₅ hollow nanocages (HNCs) with uric acid as co-reductant and co-structure-directing agent. Uric acid and cetyltrimethylammonium chloride (CTAC) played important roles in the hollow cages. The specific architectures showed remarkably enhanced catalytic properties towards glycerol oxidation reaction (GOR), ethylene glycol oxidation reaction (EGOR) and oxygen reduction reaction (ORR) with the enhanced specific activity, outperforming commercial Pt/C (20 wt%). This work provides a new avenue for rational design of novel bimetallic nanocatalysts with enhanced characters in energy storage and conversion.

A novel strategy for the synthesis of hollow Pt–Cu tetradecahedrons as an efficient electrocatalyst toward methanol oxidation

Pt–Cu TNs can be simply achieved within a few minutes by an H⁺-assisted disproportionation reaction using Cu₂O tetradecahedrons as the template. Due to its unique structural advantages, these Pt–Cu TNs exhibit extraordinary electrocatalytic performance toward MOR.

Hofmann-like metal–organic-framework-derived PtxFe/C/N-GC composites as efficient electrocatalysts for methanol oxidation

Pt_xFe/C/N-GC electrocatalysts were prepared using a composite of Hofmann-like Pt/Fe-based metal–organic frameworks and two-dimensional oxidized graphene. The Pt_xFe/C/N-GC-700 composite (annealed at 700 °C) exhibited an enhanced mass activity in the electrocatalytic methanol oxidation reaction, which was ten times higher than that of commercial Pt/C (20%) catalysts.

Pt-based bimetallic catalysts derived from Pt/Fe-based metal–organic frameworks were prepared for electrocatalytic methanol oxidation, for which the mass activity is ten times higher than that of commercial Pt/C (20%) catalysts.

Facile Synthesis of PtCu Alloy/Graphene Oxide Hybrids as Improved Electrocatalysts for Alkaline Fuel Cells

Morphology-controllable preparation of Pt-based nanoalloys supporting on carbonaceous materials is a potential strategy to enhance the catalytic properties for oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR); they are recognized as irreplaceable electrode reactions in proton-exchange membrane ethanol fuel cells. Herein, we exhibit a facile, one-step synthesis method to directly prepare composition-tunable PtCu alloy/graphene oxide (GO) hybrids. The structure of the as-synthesized PtCu alloy/GO hybrids has been analyzed using transmission electron microscopy, high resolution transmission electron microscopy, energy-dispersive X-ray, X-ray diffraction, inductively coupled plasma, and X-ray photoelectron spectroscopy. In the PtCu alloy/GO hybrids, the PtCu alloy nanoparticles well disperse on GO, and the size is below 5.0 nm. The catalysis for ORR and EOR of the as-synthesized PtCu/GO hybrids has been evaluated in alkaline solution. Compared to commercial Pt/C, the PtCu/GO hybrids exhibit much higher mass activity and stability. The mass activities toward ORR/EOR on Pt_75.4Cu_24.6/GO hybrids are 5.3/2.36 times higher than the commercial Pt/C. This study proves that the as-synthesized PtCu/GO hybrids can be used as improved catalysts for ORR and EOR in alkaline medium.

One-step fabrication of bimetallic PtNi mesoporous nanospheres as an efficient catalyst for the oxygen reduction reaction

The controlled synthesis of Pt-based bimetallic porous nanostructures is highly important for the design of electrocatalysts with high performance. Herein, we report a one-step method for the direct synthesis of well-dispersed bimetallic PtNi mesoporous nanospheres (PtNi MNs) at high yield. Benefitting from the synergistic effect of composition (bimetallic PtNi) and structure (mesoporous and highly open structure), the as-obtained PtNi MNs exhibit superior catalytic activity and stability for the oxygen reduction reaction.

3D-2D heterostructure of PdRu/NiZn oxyphosphides with improved durability for electrocatalytic methanol and ethanol oxidation

The rational design and engineering of bimetallic Pd-based nanocatalysts with both high activity and durability are of paramount significance for the practical applications of fuel cells. Herein, a new class of well-defined 2D NiZn oxyphosphide nanosheets (NiZnP NSs) have been successfully engineered to support unique 3D PdRu nanoflowers (PdRu NFs) via a facile strategy. Such nanohybrids with abundant surface active areas and modified electronic structure exhibit a great enhancement in electrocatalytic activity for the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR), whose mass/specific activities are 1739.5 mA mg-1/4.5 mA cm-2 and 4719.8 mA mg-1/12.3 mA cm-2, which are 8.3/9.0 and 8.3/9.5 times higher than those of commercial Pd/C catalysts, respectively. More interestingly, with the remarkable promotional effect of NiZnP NSs, such 3D-2D PdRu/NiZn oxyphosphide nanohybrids can even retain 72.4% and 70.1% of initial catalytic activity toward MOR and EOR for 1000 potential cycles with negligible morphological or compositional variations. The successful construction of this new class of electrocatalysts opens up a new way for designing 3D-2D nanohybrids with high performance for electrochemical reactions and beyond.

Bimetallic Platinum-Rhodium Alloy Nanodendrites as Highly Active Electrocatalyst for the Ethanol Oxidation Reaction

Rationally designing and manipulating composition and morphology of precious metal-based bimetallic nanostructures can markedly enhance their electrocatalytic performance, including selectivity, activity, and durability. We herein report the synthesis of bimetallic PtRh alloy nanodendrites (ANDs) with tunable composition by a facile complex-reduction synthetic method under hydrothermal conditions. The structural/morphologic features, formation mechanism, and electrocatalytic performance of PtRh ANDs are investigated thoroughly by various physical characterization and electrochemical methods. The preformed Rh crystal nuclei effectively catalyze the reduction of Pt²⁺ precursor, resulting in PtRh alloy generation due to the catalytic growth and atoms interdiffusion process. The Pt atoms deposition distinctly interferes in Rh atoms deposition on Rh crystal nuclei, resulting in dendritic morphology of PtRh ANDs. For the ethanol oxidation reaction (EOR), PtRh ANDs display the chemical composition and solution pH co-dependent electrocatalytic activity. Because of the alloy effect and particular morphologic feature, Pt₁Rh₁ ANDs with optimized composition exhibit better reactivity and stability for the EOR than commercial Pt nanocrystals electrocatalyst.

Hierarchical branched platinum-copper tripods as highly active and stable catalysts

Designing and manipulating the structure of nanomaterials can efficiently tailor their catalytic properties, enabling the promotion of both their activity and stability. We herein report the shape-controlled synthesis of advanced Pt-Cu hierarchical tripod nanocrystals (HTNCs) by controlling the amount of KI and reaction time. The as-prepared nanocrystals (NCs) look like a typical tripod on the whole, consisting of similar branch structural units. In addition, the structure of the HTNCs could also be obtained with a narrow Pt/Cu feeding ratio. Owing to the unique HTNC structure and exposed high-index facets, as well as probable electronic effects between Cu and Pt, the as-obtained Pt-Cu HTNCs can exhibit greatly enhanced electrocatalytic activity toward ethylene glycol oxidation reaction (EGOR) and glycerol oxidation (GOR), which are 5.1 and 6.5 times higher in mass activity, as well as 5.6 and 7.3 times higher in specific activity relative to commercial Pt/C, showing that they are a class of promising electrocatalyst for fuel cells. This work presents huge opportunities for optimizing the electrocatalytic oxidation reaction by designing the structure of nanocatalysts.

One-pot synthesis of bimetallic PdCu nanoframes as an efficient catalyst for the methanol oxidation reaction

A one-pot method is developed for the synthesis of PdCu nanoframes which are an active catalyst for the methanol oxidation reaction.

Rational one-step synthesis of porous PtPdRu nanodendrites for ethanol oxidation reaction with a superior tolerance for CO-poisoning

Precise fabrication of porous ternary Pt-based nanodendrites is very important for electrochemical energy conversion owing to high surface area and great molecular accessibility of these nanodendrites. Herein, PtPdRu porous nanodendrites (PNDs) were prepared via a facile one-step ultrasonic irradiation approach at room temperature. Intriguingly, the ultrasonic irradiation drove the formation of PtPdRu PNDs with spatially interconnected porous structures, whereas magnetic stirring produced PtPdRu nanoflowers (NFs) with less porosity. The formation mechanism was ascribed to the acoustic cavitation effect and fast-reduction kinetics under sonication. The as-made PtPdRu PNDs displayed a superior catalytic performance towards ethanol oxidation reaction with a high tolerance for CO-poisoning as compared to PtPdRu NFs, PtPd NDs, and commercial Pt/C catalyst.

Unique Cu@CuPt Core-Shell Concave Octahedron with Enhanced Methanol Oxidation Activity

Although tremendous efforts have been devoted to the exploration of cost-effective, active, and stable electrochemical catalysts, only few significant breakthroughs have been achieved up to now. Therefore, exploring new catalysts and improving catalyst activity and stability are still major tasks at present. Controllable synthesis of Pt-based alloy nanocrystals with a uniform high-index surface and unique architecture has been regarded as an effective strategy to optimize their catalytic efficiency toward electrochemical reactions. Accordingly, here we present a one-pot facile solvothermal process to synthesize novel unique Cu@CuPt core-shell concave octahedron nanocrystals that exhibit both outstanding activity and long durability. By regulating temperatures during the synthesis process, we were able to control the reduction rate of Cu and Pt ions, which could subsequently lead to the sequential stacking of Cu and Pt atoms. Owing to the concave structure, the as-prepared core-shell nanoparticles hold a high-index surface of {312} and {413}. Such surfaces can provide a high density of atomic steps and terraces, which is suggested to be favorable for electrochemical catalysts. Specifically, the Cu@CuPt core-shell concave octahedron presents 8.6/13.1 times enhanced specific/mass activities toward the methanol oxidation reaction in comparison to those of a commercial Pt/C catalyst, respectively. Meanwhile, the as-prepared catalyst exhibits superior durability and antiaggregation properties under harsh electrochemical conditions. The facile method used here proposes a novel idea to the fabrication of nanocrystals with desired compositional distribution, and the as-prepared product offers exciting opportunities to be applied in direct methanol fuel cells.

M13 Virus-Incorporated Biotemplates on Electrode Surfaces To Nucleate Metal Nanostructures by Electrodeposition

We report a virus-incorporated biological template (biotemplate) on electrode surfaces and its use in electrochemical nucleation of metal nanocomposites as an electrocatalytic material for energy applications. The biotemplate was developed with M13 virus (M13) incorporated in a silicate sol-gel matrix as a scaffold to nucleate Au-Pt alloy nanostructures by electrodeposition, together with reduced graphene oxide (rGO). The phage when engineered with Y3E peptides could nucleate Au-Pt alloy nanostructures, which ensured adequate packing density, simultaneous stabilization of rGO, and a significantly increased electrochemically active surface area. Investigation of the electrocatalytic activity of the resulting sol-gel composite catalyst toward methanol oxidation in an alkaline medium showed that this catalyst had mass activity greater than that of the biotemplate containing wild-type M13 and that of monometallic Pt and other Au-Pt nanostructures with different compositions and supports. M13 in the nanocomposite materials provided a close contact between the Au-Pt alloy nanostructures and rGO. In addition, it facilitated the availability of an OH^--rich environment to the catalyst. As a result, efficient electron transfer and a synergistic catalytic effect of the Au and Pt in the alloy nanostructures toward methanol oxidation were observed. Our nanocomposite synthesis on the novel biotemplate and its application might be useful for developing novel clean and green energy-generating and energy-storage materials.

A self-supporting bimetallic Au@Pt core-shell nanoparticle electrocatalyst for the synergistic enhancement of methanol oxidation

The morphology of Pt−Au bimetal nanostructures plays an important role in enhancing the catalytic capability, catalytic stability and utilization efficiency of the platinum. We designed and successfully prepared Au@Pt nanoparticles (NPs) through an economical, surfactant-free and efficient method of seed-mediated growth. The Au@Pt NPs displayed electrochemical performances superior to those of commercial Pt/C catalysts because their agglomeration was prevented and exhibited better long-term stability with respect to methanol oxidation in acidic media by efficiently removing intermediates. Among the obtained Au@Pt NPs, Au₉₀@Pt₁₀ NPs exhibited the most significantly enhanced catalytic performance for the methanol oxidation reaction (MOR). Their mass and electrochemically active surface area (ECSA)-normalized current densities are approximately 3.9 and 4.6 times higher than those of commercial Pt/C catalysts, respectively. The oxidation current densities of the Au₉₀@Pt₁₀ NPs are approximately 1.8 times higher than those of commercial Pt/C catalysts after 4000 s of continuous measurement because the small Pt NPs grown on the surface of the Au₉₀@Pt₁₀ NPs were effectively stabilized by the Au metal support. This approach may be a facile method for the synthesis of self-supported bimetallic nanostructures, which is of great significance for the development of high performance electrocatalysts and sensors.

Monodispersed sub-5.0 nm PtCu nanoalloys as enhanced bifunctional electrocatalysts for oxygen reduction reaction and ethanol oxidation reaction

The development of effective electrocatalysts with enhanced activity and stability for both the anode and the cathode reaction in fuel cells still remains a challenge. Here, we report a one-pot route to prepare monodispersed, uniform sub-5.0 nm PtCu alloy polyhedra with a narrow size distribution. These PtCu alloy polyhedra exhibit enhanced electrocatalytic activity for both cathode and anode reactions as compared to the commercial Pt/C catalyst under alkaline conditions. The specific activity and mass activity on Pt₆₈Cu₃₂ nanoalloys are 15 and 2.8 times that on Pt/C catalyst toward oxygen reduction reaction (ORR), respectively. And the peak current density and mass activity on Pt₆₈Cu₃₂ nanoalloys are 11.8 and 2.12 times that on Pt/C catalyst toward ethanol oxidation reaction (EOR), respectively. Furthermore, the as-synthesized Pt₆₈Cu₃₂ nanoalloys have much higher stability than commercial Pt/C black for both ORR and EOR. These experimental results show an effective approach to the development of monodispersed, sub-5.0 nm PtCu nanoalloys as bifunctional electrocatalysts for both the cathode and the anode reaction in fuel cells.

One-pot synthesis of PtRu nanodendrites as efficient catalysts for methanol oxidation reaction

Bimetallic Pt-based nanodendrites are of particular interest in various catalytic applications due to their high surface areas and low densities. Herein, we provide a facile method for one-pot synthesis of PtRu nanodendrites via the co-reduction of Pt and Ru precursors in oleylamine by H₂. The as-fabricated PtRu nanodendrites exhibit superior catalytic activity and durability compared with PtRu nanocrystals (NCs), synthesized under the same reaction conditions, and the commercial Pt/C catalyst towards the methanol oxidation reaction (MOR).

Rational design of porous binary Pt-based nanodendrites as efficient catalysts for direct glucose fuel cells over a wide pH range

Porous binary PtPd, AuPt, PtCu, and PtNi nanodendrites prepared by a facile one-step reduction under ultrasonic irradiation at room temperature, exhibited a substantial catalytic activity towards glucose oxidation reaction at different pH values relative to a commercial Pt/C catalyst.