scholarly journals Facile Fabrication of Self-Similar Hierarchical Micro-Nano Structures for Multifunctional Surfaces via Solvent-Assisted UV-Lasering

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 682 ◽  
Author(s):  
Shuo Zhang ◽  
Qin Jiang ◽  
Yi Xu ◽  
Chuan Fei Guo ◽  
Zhigang Wu
Keyword(s):  
High Efficiency ◽  
Hierarchical Structures ◽  
High Sensitivity ◽  
Active Surface ◽  
Active Surface Area ◽  
Application Development ◽  
Nano Structures ◽  
Self Similar ◽  
Bending Sensor ◽  
Light Absorbance

Cross-scale self-similar hierarchical micro–nano structures in living systems often provide unique features on surfaces and serve as inspiration sources for artificial materials or devices. For instance, a highly self-similar structure often has a higher fractal dimension and, consequently, a larger active surface area; hence, it would have a super surface performance compared to its peer. However, artificial self-similar surfaces with hierarchical micro–nano structures and their application development have not yet received enough attention. Here, by introducing solvent-assisted UV-lasering, we establish an elegant approach to fabricate self-similar hierarchical micro–nano structures on silicon. The self-similar structure exhibits a super hydrophilicity, a high light absorbance (>90%) in an ultra-broad spectrum (200–2500 nm), and an extraordinarily high efficiency in heat transfer. Through further combinations with other techniques, such surfaces can be used for capillary assembling soft electronics, surface self-cleaning, and so on. Furthermore, such an approach can be transferred to other materials with minor modifications. For instance, by doping carbon in polymer matrix, a silicone surface with hierarchical micro–nano structures can be obtained. By selectively patterning such hierarchical structures, we obtained an ultra-high sensitivity bending sensor. We believe that such a fabrication technique of self-similar hierarchical micro–nano structures may encourage researchers to deeply explore the unique features of functional surfaces with such structures and to further discover their potentials in various applications in diverse directions.

scholarly journals Three-Dimensionally Ordered Macroporous ZnO Framework as Dual-Functional Sulfur Host for High-Efficiency Lithium–Sulfur Batteries

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2267
Author(s):  
Haisheng Han ◽  
Tong Wang ◽  
Yongguang Zhang ◽  
Arailym Nurpeissova ◽  
Zhumabay Bakenov
Keyword(s):  
High Efficiency ◽  
High Capacity ◽  
Active Surface ◽  
Active Surface Area ◽  
Shuttle Effect ◽  
Dual Functional ◽  
Lithium Sulfur Batteries ◽  
Sulfur Host ◽  
Ordered Macroporous ◽  
Lithium Sulfur

A three-dimensionally ordered macroporous ZnO (3DOM ZnO) framework was synthesized by a template method to serve as a sulfur host for lithium–sulfur batteries. The unique 3DOM structure along with an increased active surface area promotes faster and better electrolyte penetration accelerating ion/mass transfer. Moreover, ZnO as a polar metal oxide has a strong adsorption capacity for polysulfides, which makes the 3DOM ZnO framework an ideal immobilization agent and catalyst to inhibit the polysulfides shuttle effect and promote the redox reactions kinetics. As a result of the stated advantages, the S/3DOM ZnO composite delivered a high initial capacity of 1110 mAh g−1 and maintained a capacity of 991 mAh g−1 after 100 cycles at 0.2 C as a cathode in a lithium–sulfur battery. Even at a high C-rate of 3 C, the S/3DOM ZnO composite still provided a high capacity of 651 mAh g−1, as well as a high areal capacity (4.47 mAh cm−2) under high loading (5 mg cm−2).

Synthesis of Novel Pd Nanosponges for Non-Enzymatic Glucose Sensor

2020 ◽  
Vol 20 (12) ◽  
pp. 7333-7341
Author(s):  
Feng Chen ◽  
Jing-Hao Li ◽  
Yu-Chen Chi ◽  
Zhen-Hua Dan ◽  
Feng-Xiang Qin
Keyword(s):  
Glucose Sensor ◽  
High Sensitivity ◽  
Cost Effective ◽  
Active Surface ◽  
Glucose Sensing ◽  
Active Surface Area ◽  
Long Term Stability ◽  
High Uniformity ◽  
One Step ◽  
The Cost

A unique nanostructured electrocatalyst based on Palladium (Pd) nanosponge architecture is synthesized by one-step dealloying of the amorphous alloy precursor with low Pd concentration. The sponge-like nanostructure with hollow interiors enables sufficient contact between reactants andboth the interior and exterior surfaces. The results of cyclic voltammetry reveal that the as-prepared Pd nanosponge exhibits high sensitivity of 32 μA mM−1 cm−2 in a wide linear range (1–18 mM), and long-term stability toward glucose electro-oxidation. The Pd nanosponge also manifests detection limit as low as 2.0 μM (S/N = 3) and high selectivity for glucose sensing. The enhanced catalytic activity of the Pd nanosponge is attributed to the bimetallic synergistic effect and the large active surface area of the high-uniformity porous structure. The facile synthesis of the cost-effective Pd nanosponge with superior electrocatalytic performance makes it hold great potentials for biosensor and other catalysis applications.

scholarly journals Exploring the effect of Ni/Cr contents on the sheet-like NiCr-oxide-decorated CNT composites as highly active and stable catalysts for urea electrooxidation

Clean Energy ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 58-66
Author(s):  
Qiuping Gan ◽  
Benzhi Wang ◽  
Judan Chen ◽  
Jianniao Tian ◽  
Tayirjan Taylor Isimjan ◽  
...  
Keyword(s):  
Surface Area ◽  
Current Density ◽  
High Efficiency ◽  
Catalytic Mechanism ◽  
Low Cost ◽  
Scale Up ◽  
Active Surface ◽  
Environmental Crisis ◽  
Active Surface Area ◽  
Defect Sites

Abstract The developing high-efficiency urea fuel cells have an irreplaceable role in solving the increasingly severe environmental crisis and energy shortages. The sluggish six-electron dynamic anodic oxidation reaction is the bottleneck of the rapid progress of urea fuel-cell technology. To tackle this challenge, we select the NiCr bimetallic system due to the unique synergic effect between the Ni and the Cr. Moreover, better conductivity is assured using carbon nanotubes (CNTs) as the support. Most importantly, we use a simple hydrothermal method in catalyst preparation for easy scale-up at a low cost. The results show that the hybrid catalysts of NiCrx-oxide-CNTs with different Ni/Cr ratios show much better catalytic performance in terms of active surface area and current density as compared to that of Ni-hydro-CNTs. The optimized NiCr2-oxide-CNTs catalyst exhibits not only the largest electrochemically active surface area (ESA, 50.7 m2 g−1) and the highest urea electrocatalytic current density (115.6 mA cm−2), but also outstanding long-term stability. The prominent performance of the NiCr2-oxide-CNTs catalyst is due to the combined effect of the improved charge transfer between Ni and Cr species, the large ESA, along with an elegant balance between the oxygen-defect sites and hydrophilicity. Moreover, we have proposed a synergistically enhanced urea catalytic mechanism.

Graphene Role as Platinum Support for CO and Formic Acid Electrooxidation

2011 ◽  
Vol 1326 ◽  
Author(s):  
Shirui Guo ◽  
Huseyin Sarialtin ◽  
Shaun Alia ◽  
Hayri Engin Akin ◽  
Yushan Yan ◽  
...  
Keyword(s):  
Particle Size ◽  
Fuel Cell ◽  
Formic Acid ◽  
High Efficiency ◽  
Chemical Reduction ◽  
Pt Nanoparticles ◽  
Active Surface ◽  
Active Surface Area ◽  
Support Materials ◽  
Loading Amount

AbstractThe direct methanol fuel cell (DMFC) is a promising power source for electronic applications due to its high efficiency and compactness. To improve the efficiency, many support materials have been developed. We investigated uniform graphene nanoflake films as a support for catalytic Pt nanoparticles in direct carbon monooxide and formic acid electro-oxidation. Pt nanoparticles were deposited on the surface of graphene films with chemical reduction method. Chemical functionalization of graphene with ethylenediamine enables Pt nanoparticles mobilize on graphene uniformly. By simply changing the loading amount of Pt precursor, various particle sizes were achieved. The particle size of Pt plays prominent role in fuel cell test. The electrochemically active surface area of different sample are 6.3 (5 wt% Pt/G), 4.1 (20 wt% Pt/G), and 3.0 (50 wt% Pt/G) cm2mg-1 corresponding to the particle size 3±1nm, 10±2nm, 20±2nm respectively. The results obtained are ascribed to a uniform network made of 2-4 nm Pt monolayer nanopaticles on the surface of graphene flakes. Graphene will play significant role in developing next-generation advanced Pt based fuel cells and their relevant electrodes in the field of energy.

scholarly journals High-Index-Faceted Ni3S2 Branch Arrays as Bifunctional Electrocatalysts for Efficient Water Splitting

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Shengjue Deng ◽  
Kaili Zhang ◽  
Dong Xie ◽  
Yan Zhang ◽  
Yongqi Zhang ◽  
...  
Keyword(s):  
Water Splitting ◽  
Active Sites ◽  
Large Scale ◽  
High Efficiency ◽  
Hydrogen Generation ◽  
Metal Sulfide ◽  
Value Added ◽  
Active Surface ◽  
High Index ◽  
Active Surface Area

Abstract For efficient electrolysis of water for hydrogen generation or other value-added chemicals, it is highly relevant to develop low-temperature synthesis of low-cost and high-efficiency metal sulfide electrocatalysts on a large scale. Herein, we construct a new core–branch array and binder-free electrode by growing Ni3S2 nanoflake branches on an atomic-layer-deposited (ALD) TiO2 skeleton. Through induced growth on the ALD-TiO2 backbone, cross-linked Ni3S2 nanoflake branches with exposed {$$\bar{2}10$$ 2 ¯ 10 } high-index facets are uniformly anchored to the preformed TiO2 core forming an integrated electrocatalyst. Such a core–branch array structure possesses large active surface area, uniform porous structure, and rich active sites of the exposed {$$\bar{2}10$$ 2 ¯ 10 } high-index facet in the Ni3S2 nanoflake. Accordingly, the TiO2@Ni3S2 core/branch arrays exhibit remarkable electrocatalytic activities in an alkaline medium, with lower overpotentials for both oxygen evolution reaction (220 mV at 10 mA cm−2) and hydrogen evolution reaction (112 mV at 10 mA cm−2), which are better than those of other Ni3S2 counterparts. Stable overall water splitting based on this bifunctional electrolyzer is also demonstrated.

High Efficiency for Methanol Electrooxidation of Self-Supporting 3D Nanoporous PdAg Alloy Foams

NANO ◽  
2021 ◽  
Author(s):  
Yanyan Song ◽  
Ying Chen ◽  
Lizhong He ◽  
Yunlong Wu ◽  
Xinhai He ◽  
...  
Keyword(s):  
High Efficiency ◽  
Three Dimensional ◽  
Active Surface ◽  
Atomic Ratio ◽  
Active Surface Area ◽  
Moderate Amount ◽  
Intermediate Products ◽  
Electrocatalytic Performance ◽  
One Step ◽  
Electrochemical Active Surface Area

The self-supporting three-dimensional (3D) nanoporous PdAg alloy (NP–PdAg) foams have been prepared by a simple one-step dealloying melt-spun Al–Pd–Ag ribbons in a 20[Formula: see text]wt.% NaOH aqueous solution at 90∘C for 1.5[Formula: see text]h. The structure is advantageous to the diffusion and removal of the intermediate products and the transmission of the methanol molecules. The NP–PdAg foams exhibit better electrocatalytic performance than the NP-Pd foam toward the methanol oxidation in potassium hydroxide (KOH) solution. The optimal atomic ratio of Pd to Ag in the NP–PdAg foams is 1:1, and its electrocatalytic activity is about 2.6 times that of the NP–Pd foam. The significant improvement in the electrocatalytic performance is attributed to the addition of a moderate amount of Ag. In the whole electrocatalytic process, Ag can provide OHads to oxidize the intermediate products on the surface of active Pd sites into carbon dioxide or other cleaning products. Also, the Ag can increase electrochemical active surface area and the adsorption energy of Pd to methanol molecules and OHads. These significantly prevent the accumulation of poisoning intermediates on the surface of Pd and quickly release more active Pd sites.

scholarly journals Comparative Study on the Effect of Protonation Control for Resistive Gas Sensor Based on Close-Packed Polypyrrole Nanoparticles

2020 ◽  
Vol 10 (5) ◽  
pp. 1850 ◽  
Author(s):  
Wooyoung Kim ◽  
Sunghun Cho ◽  
Jun Seop Lee
Keyword(s):  
Conducting Polymer ◽  
High Sensitivity ◽  
Active Surface ◽  
Chain Structure ◽  
Polymer Chains ◽  
Active Surface Area ◽  
Recovery Times ◽  
Response And Recovery ◽  
Polypyrrole Nanoparticles ◽  
Sensor Transducer

Conducting polymers are often used as sensor electrodes due to their conjugated chain structure, which leads to high sensitivity and rapid response at room temperature. Numerous studies have been conducted on the structures of conducting polymer nanomaterials to increase the active surface area for the target materials. However, studies on the control of the chemical state of conducting polymer chains and the modification of the sensing signal transfer with these changes have not been reported. In this work, polypyrrole nanoparticles (PPyNPs), where is PPy is a conducting polymer, are applied as a sensor transducer to analyze the chemical sensing ability of the electrode. In particular, the protonation of PPy is adjusted by chemical methods to modify the transfer sensing signals with changes in the polymer chain structure. The PPyNPs that were modified at pH 1 exhibit high sensitivity to the target analyte (down to 1 ppb of NH3) with short response and recovery times of less than 20 s and 50 s, respectively, at 25 °C.

scholarly journals 3D Electrochemical Sensor and Microstructuration Using Aerosol Jet Printing

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7820
Author(s):  
Tiziano Fapanni ◽  
Emilio Sardini ◽  
Mauro Serpelloni ◽  
Sarah Tonello
Keyword(s):  
Electrochemical Sensor ◽  
Surface Area ◽  
Electrochemical Sensors ◽  
Basic Research ◽  
High Sensitivity ◽  
Active Surface ◽  
Active Surface Area ◽  
Contact Printing ◽  
Jet Printing ◽  
Aerosol Jet Printing

Electrochemical sensors are attracting great interest for their different applications. To improve their performances, basic research focuses on two main issues: improve their metrological characteristics (e.g., repeatability, reusability and sensitivity) and investigate innovative fabrication processes. In this work, we demonstrate an innovative microstructuration technique aimed at increasing electrochemical sensor sensitivity to improve electrode active area by an innovative fabrication technique. The process is empowered by aerosol jet printing (AJP), an additive-manufacturing and non-contact printing technique that allows depositing functional inks in precise patterns such as parallel lines and grids. The 3D printed microstructures increased the active surface area by up to 130% without changing the substrate occupancy. Further, electrochemical detection of ferro/ferri-cyanide was used to evaluate the sensitivity of the electrodes. This evaluation points out a sensitivity increase of 2.3-fold on average between bare and fully microstructured devices. The increase of surface area and sensitivity are well linearly correlated as expected, verifying the fitness of our production process. The proposed microstructuration is a viable solution for many applications that requires high sensitivity, and the proposed technique, since it does not require masks or complex procedures, turns out to be flexible and applicable to infinite construction geometries.

Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kailun Yang ◽  
Recep Kas ◽  
Wilson A. Smith
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Catalyst Layer ◽  
Active Surface ◽  
Active Surface Area ◽  
High Concentration ◽  
Copper Electrodes ◽  
Surface Enhanced ◽  
Local Current

<p>This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer. </p> <p> </p>

Trends in Diagnosis for Active Tuberculosis Using Nanomaterials

2019 ◽  
Vol 26 (11) ◽  
pp. 1946-1959 ◽  
Author(s):  
Le Minh Tu Phan ◽  
Lemma Teshome Tufa ◽  
Hwa-Jung Kim ◽  
Jaebeom Lee ◽  
Tae Jung Park
Keyword(s):  
Sensitivity And Specificity ◽  
High Efficiency ◽  
Point Of Care ◽  
High Sensitivity ◽  
Signs And Symptoms ◽  
Diagnostic Methods ◽  
Advantages And Disadvantages ◽  
Treatment And Prevention ◽  
Clinical Tools ◽  
Diagnostic Applications

Background:Tuberculosis (TB), one of the leading causes of death worldwide, is difficult to diagnose based only on signs and symptoms. Methods for TB detection are continuously being researched to design novel effective clinical tools for the diagnosis of TB.Objective:This article reviews the methods to diagnose TB at the latent and active stages and to recognize prospective TB diagnostic methods based on nanomaterials.Methods:The current methods for TB diagnosis were reviewed by evaluating their advantages and disadvantages. Furthermore, the trends in TB detection using nanomaterials were discussed regarding their performance capacity for clinical diagnostic applications.Results:Current methods such as microscopy, culture, and tuberculin skin test are still being employed to diagnose TB, however, a highly sensitive point of care tool without false results is still needed. The utilization of nanomaterials to detect the specific TB biomarkers with high sensitivity and specificity can provide a possible strategy to rapidly diagnose TB. Although it is challenging for nanodiagnostic platforms to be assessed in clinical trials, active TB diagnosis using nanomaterials is highly expected to achieve clinical significance for regular application. In addition, aspects and future directions in developing the high-efficiency tools to diagnose active TB using advanced nanomaterials are expounded.Conclusion:This review suggests that nanomaterials have high potential as rapid, costeffective tools to enhance the diagnostic sensitivity and specificity for the accurate diagnosis, treatment, and prevention of TB. Hence, portable nanobiosensors can be alternative effective tests to be exploited globally after clinical trial execution.

Sign in / Sign up

Export Citation Format

Share Document