Nanoporous platinum–cobalt alloy for electrochemical sensing for ethanol,hydrogen peroxide,and glucose

Nanoporous platinum–cobalt (NP–PtCo) alloy with hierarchical nanostructure is straightforwardly fabricated by dealloying PtCoAl alloy in a mild alkaline solution. Selectively etching Al resulted in a hierarchical three-dimensional network nanostructure with a narrow size distribution at 3 nm. The as-prepared NP–PtCo alloy shows superior performance toward ethanol and hydrogen peroxide (H₂O₂) with highly sensitive response due to its unique electrocatalytic activity. In addition, NP–PtCo also exhibits excellent amperometric durability and long-term stability for H₂O₂ as well as a good anti-interference toward ascorbic acid, uric acid, and dopamine. The hierarchical nanoporous architecture in PtCo alloy is also highly active for glucose sensing electrooxidation and sensing in a wide linear range. The NP–PtCo alloy holds great application potential for electrochemical sensing with simple preparation, unique catalytic activity, and high structure stability.     

Direct carbonization of Al-based porous coordination polymer for synthesis of nanoporous carbon

Nanoporous carbon (NPC) is prepared by direct carbonization of Al-based porous coordination polymers (Al-PCP). By applying the appropriate carbonization temperature, both high surface area and large pore volume are realized for the first time. Our NPC shows much higher porosity than other carbon materials (such as activated carbons and mesoporous carbons). This new type of carbon material exhibits superior sensing capabilities toward toxic aromatic substances.     

A three-dimensional hierarchical nanoporous PdCu alloy for enhanced electrocatalysis and biosensing

Nanoporous copper (NPC) obtained by dealloying CuAl alloy is used as both three-dimensional template and reducing agent for the fabrication of nanoporous PdCu alloy with hollow ligaments by a simple galvanic replacement reaction with H₂PdCl₄ aqueous solution. Electron microscopy and X-ray diffraction characterizations demonstrate that after the replacement reaction, the ligaments become hollow tubular structure and the ligament shell is also comprised of small pores and nanoparticles with a typical size of ∼4 nm (third order porosity). The as-prepared nanotubular mesoporous PdCu alloy (NM-PdCu) structure exhibits remarkably improved electrocatalytic activity towards the oxidation of formic acid and H₂O₂ compared with nanoporous Pd (NP-Pd), and can be used for sensitive electrochemical sensing applications. After coupled with glucose oxidase (GOx), the enzyme modified NM-PdCu electrode can sensitively detect glucose over a wide linear range (0.5–20 mM).     

Electrochemical stability of self-assembled monolayers on nanoporous Au

Desorption of thiolate self-assembled monolayers (SAMs) seriously limits the fabrication of thiol-based devices. Here we demonstrate that nanoporous Au produced by dealloying Au-Ag alloys exhibits high electrochemical stability against thiolate desorption. Nanoporous Au has many defective sites, lattice strain and residual Ag on the ligament surface. First-principles calculations indicate that these surface aspects increase the binding energy between a SAM and the surface of nanoporous Au.     

Nanoporous carbons through direct carbonization of a zeolitic imidazolate framework for supercapacitor electrodes

Nanoporous carbons with high surface area are achieved through direct carbonization of a commercially available zeolitic imidazolate framework (ZIF-8) without any additional carbon sources. The resultant nanoporous carbons exhibit high electrochemical capacitances in an acidic aqueous electrolyte.     

Nanoporous Carbon Tubes from Fullerene Crystals as the π‐Electron Carbon Source

Here we report the thermal conversion of one‐dimensional (1D) fullerene (C₆₀) single‐crystal nanorods and nanotubes to nanoporous carbon materials with retention of the initial 1D morphology. The 1D C₆₀ crystals are heated directly at very high temperature (up to 2000 °C) in vacuum, yielding a new family of nanoporous carbons having π‐electron conjugation within the sp²‐carbon robust frameworks. These new nanoporous carbon materials show excellent electrochemical capacitance and superior sensing properties for aromatic compounds compared to commercial activated carbons.     

Synthesis of Nanoporous Carbon–Cobalt‐Oxide Hybrid Electrocatalysts by Thermal Conversion of Metal–Organic Frameworks

Nanoporous carbon–cobalt‐oxide hybrid materials are prepared by a simple, two‐step, thermal conversion of a cobalt‐based metal–organic framework (zeolitic imidazolate framework‐9, ZIF‐9). ZIF‐9 is carbonized in an inert atmosphere to form nanoporous carbon–metallic‐cobalt materials, followed by the subsequent thermal oxidation in air, yielding nanoporous carbon–cobalt‐oxide hybrids. The resulting hybrid materials are evaluated as electrocatalysts for the oxygen‐reduction reaction (ORR) and the oxygen‐evolution reaction (OER) in a KOH electrolyte solution. The hybrid materials exhibit similar catalytic activity in the ORR to the benchmark, commercial, Pt/carbon black catalyst, and show better catalytic activity for the OER than the Pt‐based catalyst.     

聚吡咯/硝酸活化碳气凝胶纳米复合材料的制备表征及其在超级电容器中的应用

通过化学氧化聚合法制备出不同比例的聚吡咯(PPY)/硝酸活化碳气凝胶(HCA)复合材料。采用傅里叶变换红外光谱(FT-IR)和扫描电子显微镜(SEM)表征材料的成分和形貌,结果表明,通过硝酸活化及与聚吡咯的复合,并未破坏碳气凝胶的多孔形貌,硝酸活化碳气凝胶及聚吡咯/硝酸活化碳气凝胶都仍然保持着原碳气凝胶的三维纳米多孔结构。采用对照实验的方法,设计并合成五组不同配比的复合材料,聚吡咯与硝酸活化碳气凝胶的质量比例分别为3:1、2:1、1:1、1:2、1:3,通过循环伏安法,恒流充放电,交流阻抗及循环性测试等考察材料的电化学性能。结果证明,当聚吡咯与硝酸活化碳气凝胶比例为1:1时,复合材料显示出最优电化学性能:比电容高达336 F·g^-1,是纯碳气凝胶(103 F·g^-1)的三倍有余,除此还显示出卓越的导电性与循环稳定性, 2000次循环后仍保持初始电容的91%,具备优良的超级电容器电极材料性能。因此聚吡咯/硝酸活化碳气凝胶复合纳米材料是超级电容器的理想电极材料。     

Nanoporous thermosetting polymers

Potential applications of nanoporous thermosetting polymers include polyelectrolytes in fuel cells, separation membranes, adsorption media, and sensors. Design of nanoporous polymers for such applications entails controlling permeability by tailoring pore size, structure, and interface chemistry. Nanoporous thermosetting polymers are often synthesized via free radical mechanisms using solvents that phase separate during polymerization. In this work, a novel technique for the synthesis of nanoporous thermosets is presented that is based on the reactive encapsulation of an inert solvent using step-growth cross-linking polymerization without micro/macroscopic phase separation. The criteria for selecting such a monomer-polymer-solvent system are discussed based on FTIR analysis, observed micro/macroscopic phase separation, and thermodynamics of swelling. Investigation of resulting network pore structures by scanning electron microscopy (SEM) and small-angle X-ray scattering following extraction and supercritical drying using carbon dioxide showed that nanoporous polymeric materials with pore sizes ranging from 1 to 50 nm can be synthesized by varying the solvent content. The differences in the porous morphology of these materials compared to more common free radically polymerized analogues that exhibit phase separation were evident from SEM imaging. Furthermore, it was demonstrated that the chemical activity of the nanoporous materials obtained by our method could be tailored by grafting appropriate functional groups at the pore interface.     

The characteristics of highly ordered mesoporous carbons as electrode material for electrochemical sensing as compared with carbon nanotubes

In this paper, the unique properties of highly ordered mesoporous carbons modified glassy carbon electrode (OMCs/GE) are illustrated from comparison with carbon nanotubes modified glassy carbon electrode (CNTs/GE) for the electrochemical sensing applications. Electrochemical behaviors of eight kinds of inorganic and organic electroactive compounds were studied at OMCs/GE, which shows more favorable electron transfer kinetics than that at CNTs/GE. Especially, OMCs/GE exhibits remarkably strong and stable electrocatalytic response toward NADH compared with CNTs/GE. The ability of OMCs to promote electron transfer not only provides a new platform for the development of dehydrogenase-based bioelectrochemical devices, but also indicates a potential of OMCs in a wide range of sensing applications. OMCs prepared are the novel carbon electrode materials, exhibiting more favorable electrochemical reactivity than CNTs for the wide electrochemical sensing applications without pretreatments, while purification or end-opening processing was usually required in case of CNTs.     

Porous Nanostructured Metals for Electrocatalysis

Nanoporous metals have been used to enhance electrocatalysis. The origin of their capability is understood on the basis of enlarged surface area. On the other hand, the nanoconfined space of nanoporous metals can significantly affect the electrochemical efficiency. Moreover, molecular dynamics in nanoconfined spaces is capable of offering much more chances of interaction between a redox molecule and a metal surface. These unique properties come from simply nanoporous structure and suggest new opportunity to innovative electrocatalysts in the future. This review addresses recent advances in the field of nanoporous metals and discusses respective important electrocatalytic applications.     

Nanoporous gold electrode prepared from gold compact disk as the anode for the microbial fuel cell

The electrodes (anode and cathode) have an important role in the efficiency of a microbial fuel cell (MFC), as they can determine the rate of charge transfer in an electrochemical process. In this study, nanoporous gold electrode, prepared from commercially available gold-made compact disk, is utilized as the anode in a two-chamber MFC. The performance of nanoporous gold electrode in the MFC is compared with that of gold film, carbon felt and acid-heat-treated carbon felt electrodes which are usually employed as the anode in the MFCs. Electrochemical surface area of nanoporous gold electrode exhibits a 7.96-fold increase rather than gold film electrode. Scanning electron microscopy analysis also indicates the homogeneous biofilm is formed on the surface of nanoporous gold electrode, while the biofilm formed at the surface of acid-heat-treated carbon felt electrode shows rough structure. Electrochemical studies show although modifications applied on carbon felt electrodes improve its performance, nanoporous gold electrode, due to its structure and better electrochemical properties, acts more efficiently as the MFC’s anode. The maximum power density produced by nanoporous gold anode is 4.71 mW m^?2 at current density of 16.00 mA m^?2, while this value for acid-heat-treated carbon felt anode is 3.551 mW m^?2 at current density of 9.58 mA m^?2.     

Synthesis and electrochemical performance of nanoporous Li4Ti5O12 anode material for lithium-ion batteries

Nanoporous Li₄Ti₅O₁₂ (N-LTO) was prepared by sol–gel method using monodisperse polystyrene spheres as a template and followed by calcination process. The as-prepared N-LTO has a spinel structure, large special surface area, and nanoporous structure with the pore average diameter of about 100?nm and wall thickness of 50?nm. Electrochemical experiments show that N-LTO exhibits a high initial discharge capacity of 189?mAh?g^?1 at 0.1?C rate cycled between 0.5 and 3.0?V and excellent capacity retention of 170?mAh?g^?1 after 100?cycles. EIS and CV analysis show that N-LTO has a higher mobility for Li⁺ diffusion and a higher exchange current density, indicating an improved electrochemical performance. It is believed that the nanoporous structure has a larger electrode/electrolyte contact area, resulting in better electrochemical properties at high charge/discharge rates.     

Controlled Synthesis of Nanoporous Nickel Oxide with Two‐Dimensional Shapes through Thermal Decomposition of Metal–Cyanide Hybrid Coordination Polymers

The urgent need for nanoporous metal oxides with highly crystallized frameworks is motivating scientists to try to discover new preparation methods, because of their wide use in practical applications. Recent work has demonstrated that two‐dimensional (2D) cyanide‐bridged coordination polymers (CPs) are promising materials and appropriate for this purpose (Angew. Chem. Int. Ed.­ 2013 , 52, 1235). After calcination, 2D CPs can be transformed into nanoporous metal oxides with a highly accessible surface area. Here, this strategy is adopted in order to form 2D nanoporous nickel oxide (NiO) with tunable porosity and crystallinity, using trisodium citrate dihydrate as a controlling agent. The presence of trisodium citrate dihydrate plays a key role in the formation of 2D nanoflakes by controlling the nucleation rate and the crystal growth. The size of the nanoflakes gradually increases by augmenting the amount of trisodium citrate dihydrate in the reaction. After heating the as‐prepared CPs in air at different temperatures, nanoporous NiO can be obtained. During this thermal treatment, organic units (carbon and nitrogen) are completely removed and only the metal content remains to take part in the formation of nanoporous NiO. In the case of large‐sized 2D CP nanoflakes, the original 2D flake‐shapes are almost retained, even after thermal treatment at low temperature, but they are completely destroyed at high temperature because of further crystallization in the framework. Nanoporous NiO with high surface area shows significant efficiency and interesting results for supercapacitor application.     

Carbon Nanotubes/Poly(1,2‐diaminobenzene) Nanoporous Composite Film Electrode Prepared by Multipulse Potentiostatic Electropolymerisation and Its Application to Determination of Trace Heavy Metal Ions

A novel method for the fabrication of carbon nanotubes/poly(1,2‐diaminobenzene) nanoporous composite based electrode was proposed. By multipulse potentiostatic electropolymerization, the multi‐walled carbon nanotubes (MWNTs) and poly(1,2‐diaminobenzene) were deposited simultaneously on the electrode surface. Compared with the composite prepared by the traditional potentiodynamic method, the composite synthesized by multipulse potentiostatic method has a unique nanoporous structure, exhibits excellent conductivity and better environmental stability. The surface of the resulting electrode was characterized with scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The nanoporous composite film modified glassy carbon electrode was also used successfully for the simultaneously voltammetric determination of trace level of Cd²⁺ and Cu²⁺ at first‐time. Under the optimal conditions, the determination limits of 0.25 and 0.33 ppb for Cd²⁺ and Cu²⁺ were obtained, respectively. The calibration graphs were linear in the concentration range of 5–100 ppb. The electrode system provides an excellent platform for ultra sensitive electrochemical sensors for chemical and biological sensing.     

Amperometric glucose sensor based on platinum–iridium nanomaterials

This communication reports on a novel amperometric glucose sensor based on nanoporous Pt–Ir catalysts. Pt–Ir nanostructures with different contents of iridium were directly grown on Ti substrates using a one-step facile hydrothermal method and were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy. Our electrochemical study has shown that the nanoporous Pt–Ir(38%) electrode exhibits very strong and sensitive amperometric responses to glucose even in the presence of a high concentration of Cl⁻ and other common interfering species such as ascorbic acid, acetamidophenol and uric acid, promising for nonenzymatic glucose detection.     

Crystal growth of nanoporous metal organic frameworks

Nanoporous metal organic frameworks (MOFs) form one of the newest families of crystalline nanoporous material that is receiving worldwide attention. Successful use of MOFs for application requires not only development of new materials but also a need to control their crystal properties such as size, morphology, and defect concentration. An understanding of the crystal growth processes is necessary in order to aid development of routes to control such properties of the crystallites. In this Perspective article we aim to provide a short overview of the current work and understanding concerning the nucleation and growth processes of nanoporous MOFs and how this work may be expanded upon to further our comprehension of this subject. We also focus heavily on in situ studies that provide real time information on the developing materials and generally provide the most conclusive findings on the processes under investigation.     

Nanoporous carbon sorbent for molecular-sieve chromatography of lipoprotein complex

The physicochemical characteristics of carbon sorbents are investigated. Electron microscopy data for the sorbent and separated lipoprotein complex are presented. It is found that the obtained carbon sorbent possess high porosity. Nanoporous carbon sorbents for the chromatography of molecular-sieve markers are obtained and tested. The applicability of nanoporous carbon sorbents for separation of lipoprotein complexes (LPC) is investigated.     

Electrocatalytic reduction of carbon dioxide over reduced nanoporous zinc oxide

Nanoporous zinc oxide (ZnO) is prepared by a hydrothermal method followed by thermal decomposition for electrocatalytic reduction of CO₂. In situ X-ray absorption spectroscopy results indicate that ZnO is reduced to Zn under the electrolysis conditions for catalyzing CO₂ electroreduction. The reduced nanoporous ZnO exhibits obviously higher CO Faradaic efficiency and current density than commercial Zn foil with a maximum CO Faradaic efficiency of 92.0%, suggesting that the nanoporous structure facilitates electrocatalytic reduction of CO₂ over reduced nanoporous ZnO, probably due to increased surface area and more coordination unsaturated surface atoms.     

Synthesis of perpendicular nanorod arrays with hierarchical architecture and water slipping superhydrophobic properties

The utilization of vertically aligned smooth gold nanorod arrays with and without nanoporous tip architectures as superhydrophobic surfaces is described. Nanoporous architecture was produced on the tips of nanorods by selectively dissolving less noble components from the alloy nanorods. The resulting nanoscopic dual-size roughness features enhanced the surface dewettability after surface modification with low-surface-energy materials such as long-chain normal alkanethiols and fluorinated organic compounds. The surface cleaning properties were also tested with a rolling water droplet.