Design of 3D Hollow Porous Heterogeneous Nickel-Cobalt Phosphides for Synergistically Enhancing Catalytic Performance for Electrooxidation of Methanol

The synergistic effect among different components and the structural and morphological control of catalytic nanomaterials have attracted considerable research interest in the field of electrocatalysis, as using a rational design of the catalytic nanomaterials with the desired structure, morphology, and chemical compositions is an effective strategy for enhancing catalytic performance. Here, by changing the Ni/Co atomic ratio of raw materials, a series of samples with a three-dimensional (3D) hollow porous ternary multicomponent heterostructure has been successfully synthesized via a facile template-free solvothermal approach and subsequently annealing and phosphating treatments, and its formation mechanism is also investigated. By virtue of compositional and structural advantages, the optimized Ni₁Co₂P_x (NiCoP/CoP/CoP₂) nanoparticles show very high mass activity (436.9 mA mg^-1) and area-specific activity (155 mA cm^-2), as well as remarkable durability toward the methanol electrooxidation reaction (MOR) in alkaline solution. This catalytic activity is better than those of most of reported Ni/Co-based nonprecious metal catalysts. Particularly, a multicomponent synergistic effect on the MOR was observed. The present study not only provides a simple method for the fabrication of 3D hollow porous multicomponent composite nanomaterials, but also gives insights into the synergistic effect among the porous structure, chemical compositions, and catalytic activity of nanomaterials in the electrocatalytic oxidation of methanol.

Facile Synthesis Of Composition-Controllable PtPdAuTe Nanowires As Superior Electrocatalysts For Direct Methanol Fuel Cells

Multicomponent Pt-based nanowires (NWs) have attracted widespread attention as eletrocatalysts toward direct alcohol fuel cells because of their unique one-dimensional structure and high reaction dynamics. Quaternary PtPdAuTe NWs are designed via a facile template method, and NWs with a different composition are obtained by adjusting the feed ratio of metal precursors. The direct displacement reaction of metal precursors with Te NWs and the partial oxidation of Te lead to the formation of quaternary NWs. The rough surface and abundant reactive sites deriving from the rearrangement of metal atoms on the Te NWs surface endow the PtPdAuTe NWs with a superior electrocatalytic property and durability for methanol oxidation. The Pt₂₀ Pd₂₀ Au₁₀ Te₅₀ NWs display the largest mass activity and best stability among all catalysts. The preparation of PtPdAuTe NWs could provide a viable strategy for the preparation of other multicomponent NWs.

Alleviating concentration polarization: a micro three-electrode interdigitated glucose sensor based on nanoporous gold from a mild process

Precisely detecting the concentration of glucose in the human body is an attractive way to prevent or diagnose diabetes. Compared with the traditional enzyme-based electrochemical glucose sensors, the non-enzymatic ones have gradually come to people's attention recently. By integrating three electrodes into one device, glucose sensors can achieve superior performance and are convenient to carry. Herein, a non-enzymatic three-electrode interdigitated glucose sensor (TEIDGS) based on nanoporous gold is designed and fabricated. To our best knowledge, it is the first time that interdigitated electrodes are combined in a single non-enzymatic glucose sensor device. Due to the advantage of the interdigitated structure and the smart design of the three-electrode circuit board, the TEIDGS can effectively reduce concentration polarization and achieve a high detective sensitivity for glucose of 1217 μA mM-1 cm-2 and 343 μA mM-1 cm-2 in the ranges of 0.001-0.590 mM and 0.59-7.00 mM, respectively. Moreover, a low detection limit of 390 nM can be reached. In addition, this TEIDGS possesses excellent selectivity for glucose among other interferents. Strikingly, after three weeks of operation, it can still retain a high detection performance. This work will certainly provide an efficient structure and proper catalytic material choice for future non-enzymatic glucose sensors.

Finely Composition-Tunable Synthesis of Ultrafine Wavy PtRu Nanowires as Effective Electrochemical Sensors for Dopamine Detection

Preparing Pt-based one-dimensional (1D) ultrafine nanowires with abundant structural defects/grain boundaries and exploring their novel applications have attracted great interest in real-world applications. Here we introduce an environmentally friendly, facile aqueous solution approach to directly prepare a series of sub-3.0 nm PtRu ultrafine wavy nanowires. Characterizations show that the PtRu nanowires are alloy polycrystalline structures with abundant structural defects/grain boundaries. We first introduce the as-synthesized PtRu nanowires into electrochemical biosensors for the detection of DA and find that the Pt₇Ru₃ nanowires exhibit excellent electrocatalytic activity to DA with fast response, ultralow limit of detection, and excellent selectivity at a potential of 0.3 V in 0.1 M phosphate buffered solution (pH 7.2). This study shows an effective approach to the development of ultrafine PtRu nanowires as electrocatalysts for electrochemical nonenzymatic dopamine biosensors.

Facile one-pot surfactant-free synthesis of uniform Pd6Co nanocrystals on 3D graphene as an efficient electrocatalyst toward formic acid oxidation

Ultrasmall and uniform Pd6Co nanocrystals were deposited on 3D graphene by a facile one-pot surfactant-free route for a catalyst toward formic acid oxidation, showing a much higher electrocatalytic activity, larger peak current density and better stability than Pd/3DG, Pd/C as well as commercial Pd-C, and thus offering great potential for an efficient anode catalyst toward high performance direct formic acid fuel cells.

Synthesis of graphene-supported one-dimensional nanoporous Pt based catalysts, and their enhanced performance on methanol electro-oxidation

A novel approach is developed to synthesize PtIr or Pt nanowires (NWs) supported on the reduced graphene oxide (RGO) using Te NWs as template based on the replacement reaction. The resulting RGO-supported PtIr and Pt electrocatalysts are characterized by transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy and electrochemical techniques. TEM images show that these Pt based catalysts are uniformly distributed in the matrix of graphene with a characteristic of one-dimensional (1D) nanoporous structure. As one of promising anode materials used in the direct methanol fuel cells, these 1D nanoporous PtIr/RGO (or Pt/RGO) hybrids exhibit an enlarged electroactive surface and enhanced catalytic activity toward the methanol reaction relative to those PtIr or Pt NWs without graphene support.

Selective decoration of nanocrystals on single-crystalline PtTe nanowires based on a solid-state reaction

We demonstrate the fabrication of single-crystalline PtTe nanowires with/without decoration of Sb nanocrystals via thermal annealing of Sb₂Te₃/Pt and Te/Pt core/shell nanowires.

In situ growth of nickel selenide nanowire arrays on nickel foil for methanol electro-oxidation in alkaline media

NiSe nanowire arrays solvothermally grown on nickel foil behave as an efficient 3D anode for electro-catalytic oxidation of methanol in alkaline media with strong durability.

Facile preparation of ultralong dendritic PtIrTe nanotubes and their high electrocatalytic activity on methanol oxidation

A facile wet chemical approach was developed to prepare ultralong PtIrTe nanotubes (NTs) using Te nanowires (NWs) as template. These PtIrTe NTs were made up of Pt nanodendrites uniformly arrayed on the surface of IrTe NTs and interweaved with each other to nanopores. Their morphology, structure, and composition were investigated by transition electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. As expected, these PtIrTe NTs catalysts show a larger surface area, a stronger CO tolerance, and a higher catalytic activity toward electrochemical oxidation of methanol relative to the commercial Pt catalysts due to the 1D porous core-shell structure and the modification of the electronic effect by Ir.