Carbon Nanohybrid Research Articles

Electrochemical Determination of Hydrogen Peroxide Based on the Synergistic Effect of Nitrogen-Doped Porous Carbon/Carbon Nanohybrid Aerogel

In this paper, a new hydrogen peroxide electrochemical sensor based on the synergistic modification of nitrogen-doped porous carbon (NPC) and carbon nanohybrid aerogel (CNA) is proposed. NPC has been successfully synthesized from porous polyacrylonitrile (PAN) precursor by pre-oxidation to obtain adequate pyridinic-N, which contributes to enhance the electrocatalytic activity. Simultaneously, CNA has been also prepared by self-assembly in a hydrothermal environment without any interference followed by vacuum freeze drying. The final products were characterized by diversiform techniques including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD). The results showed that the NPC with 23.18% pyridinic-N exhibited well-defined and interconnected three-dimensional (3D) porous microstructure and CNA which encapsulates [Formula: see text]-Fe2O3 particles was obtained. The sensor fabricated by NPC and CNA delivered a wide linear range from 60[Formula: see text][Formula: see text]M to 1680[Formula: see text][Formula: see text]M ([Formula: see text]) and 1680[Formula: see text][Formula: see text]M to 3335[Formula: see text][Formula: see text]M ([Formula: see text]) with sensitivities of 3.98[Formula: see text][Formula: see text]A mM[Formula: see text] and 5.56[Formula: see text][Formula: see text]A mM[Formula: see text], respectively. Furthermore, the obtained sensor showed low detection limit (4.478[Formula: see text][Formula: see text]M, [Formula: see text]/[Formula: see text]), good selectivity and repeatability, rapid response and satisfying practicability.

Performance evaluation of PV-TEC coupling device for power production with improved hybrid nanocarbon based thermal material interface

The waste heat harnessing from photovoltaic module (PV) with the thermoelectric device (TE) is considered as an ideal solution for effective thermal management of PV technologies. However, idealized operating conditions for lossless device coupling and reduction in thermal contact resistance need to be investigated further to expedite PV-TE device efficiency. Our simple approach to tandemly attach a low-cost thermoelectric cooling device (TEC) to PV module has improved its power output and electrical efficiency by 1.02% and 1.1% respectively (No. of TEC device-1, 720 W/m2 and 20 °C of water-cooling). Herein, we explored the TEC device for power production as a cost-effective alternative to the traditional thermoelectric (TEG) devices. To facilitates the facile heat transport among the PV-TEC interface, the thermal interface material (TIM) has been applied on TEC devices. The hybridized paste of nanocarbon and thermal grease (NC-TG) was used as a TIM material, morphologically evident the linear alignment between NC in TG matrix has ameliorated the uniform heat conduction. It was observed that the application of hybrid Carbon TIM materials enhances the power generation by 10.65% compared to PV-TG-TEC. The physicochemical analysis and evaluation results indicated that the low-cost synthesized hybrid carbon-based TIM material is efficient in the reduction of thermal contact resistance. Concomitantly, the high heat absorption capacity of nanocarbon accelerated the TEC performance by creating a sufficient temperature gradient across TEC ends. The present work proposed a simple and low-cost pathway for the improvement of TEC performance using hybrid carbon-based TIM material.

A high‐performance hybrid supercapacitor electrode based on ZnO/nitrogen‐doped carbon nanohybrid

AbstractHybrid nanomaterials offer promising properties to serve as an electrode for hybrid supercapacitors. Herein, dye (rhodamine B, RhB) encapsulated zeolitic imidazolate frameworks (RhB@ZIF‐8) was synthesized at room temperature via triethylamine (TEA)‐assisted method. The material was used as a precursor for synthesizing zinc oxide embedded nitrogen‐doped carbon (ZnO@N‐doped C) via the carbonization at different temperatures (400°C, 600°C, and 800°C). The materials were characterized using X‐ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermal analysis (DTA), high‐resolution transmission electron microscope (HR‐TEM), energy‐dispersive X‐ray mapping (EDX), nitrogen adsorption–desorption isotherm, and X‐ray photoelectron microscope (XPS). ZnO@N‐doped C nanocrystals (15–20 nm) were used as an electrode for a hybrid supercapacitor. ZnO@N‐doped C exhibited a high capacitance of 1200 F·g−1 at a current density of 1 A·g−1 without losing any capacitance (87.7% of initial capacitance) even after 1000 galvanostatic charge–discharge cycles (GCDCs). The presence of a guest molecule such as RhB improved the capacitance of the carbonized ZIF‐8 two‐fold compared with the carbonized materials using conventional ZIF‐8.

Improvements in the thermomechanical and electrical behavior of hybrid carbon-epoxy nanocomposites

• Chemical functionalization on reinforcements produces good dispersion in epoxy matrix. • Slight amounts of hybrid reinforcement generate better performance than only one nanomaterial. • Hybrid nanocarbons contribute outstandingly in the thermomechanical and electrical properties. • Raman mapping on composites fracture surface evidenced the contribution of nanomaterials. In this work, polymeric composites of epoxy matrix reinforced with 1D and 2D nanocarbon allotropes are reported. Hybrid 3D nanostructures formed from 1D multi-walled carbon nanotubes and 2D graphene derivatives improve the electrical and thermomechanical response of the synthesized nanocomposites. Additionally, oxygenated moieties in the surface of the sp 2 carbon allotropes positively influences the dispersion of nanomaterials in the matrix and promote better interfaces among the polymeric matrix and reinforcements. Raman spectroscopy detects the different interactions of polymeric chains with carbon nanomaterials in different loads. Furthermore, Raman mapping shows the carbon dispersion regions and the influence on the final mechanical properties of the materials. The viscoelastic response evaluated by Dynamical Mechanical Analysis shows improvements of up to 138% in the storage modulus of nanocomposites with oxidized nanostructures in comparison to neat epoxy. 3D nanostructures changed the insulating nature of epoxy when the carbon nanomaterials formed the interconnected network. Some nanocomposites show an abrupt change from the insulator epoxy resin toward a semiconductor response, mainly in hybrids reinforced with pristine multi-walled carbon nanotubes and reduced graphene oxide. The TEM images of the nanocomposites showed interconnections between the 1D-2D hybrid carbon nanomaterials, which suggest a synergetic effect.

Self-standing graphitized hybrid Nanocarbon electrodes towards high-frequency supercapacitors

Carbon materials are considered as the ideal electrode materials for supercapacitors due to their diverse structure and nature. However, their poor frequency response is an obstacle to their application in high-frequency supercapacitors. Herein, an ultra-high temperature graphitization process at 2800 °C is proposed to fabricate carbon nanotubes/graphene hybrid films that are successfully employed as the electrode materials of high-frequency supercapacitors. By rational hybridization, the carbon nanotubes/graphene interlinked networks offer fast ion transport paths. Importantly, via a graphitization process at 2800 °C, the as-obtained hybrid films exhibit an ultrahigh in-plane conductivity of 491.81 S cm−1 and favorable out-plane conductivity of 27.98 mS cm−1. Such design brings the as-constructed high-frequency supercapacitors an unprecedented phase angle (up to −56.23°) and area capacitance (up to 230.56 μF cm−2) at 120 Hz, and their cut-off frequency can be nearly 30 times higher than that of films carbonization at 1600 °C. Such increases, further supported by density functional theory (DFT) calculations, are partly attributable to enhancements of ion response arising from the repair of edge defects of graphene. These findings will provide a new method in designing the structure of carbon electrodes for enhancing SCs frequency response performances.

Bacterial pigments coupled $$\hbox {TiO}_2$$-carbon nanohybrid: understanding the interfacial effect on enhanced Fluorescence

Bacterial pigments coupled $$\hbox {TiO}_2$$-carbon nanohybrid: understanding the interfacial effect on enhanced Fluorescence

Electrical conductivity of poly(methyl methacrylate) nanocomposites containing interconnected carbon nanohybrid network based on Pickering emulsion strategy

ABSTRACT The formation of three-dimensional (3D) interconnected carbon network throughout insulative polymer matrix is advantageous to elaborating electrically conductive nanocomposites. Herein, oil-in-water (O/W) Pickering emulsion stabilized by carbon nanohybrids assembled with reduced graphene oxide (RGO) and carbon nanotubes (CNTs) was utilized as a template to achieve core-shell structured poly(methyl methacrylate) (PMMA) microsphere. The effect of synthesis time on the amphiphilicity of carbon nanohybrid stabilizer is studied. Investigations on the as-prepared Pickering emulsion and the electrical conductivity of the derived carbon nanohybrid composites were directed with respect to the concentration and formulation of carbon nanohybrid stabilizer, respectively. Considering a balance between electrical and mechanical properties, 0.74 wt% of carbon nanohybrid stabilizer was used to form O/W Pickering emulsion, which was responsible for the electrical conductivity of 4 × 10−8 S m−1 for the resulting RGO/CNTs/PMMA nanocomposites. The processing-structure-property relationship of carbon nanocomposites based on O/W Pickering emulsion strategy is further demonstrated in scanning electron microscopy (SEM) observation and thermo-mechanical analysis. The processing and functional synergies between GO and CNTs are identified to efficiently construct interconnected electrically conductive pathway in polymer matrix.

Sustained-Release Method for the Directed Synthesis of ZIF-Derived Ultrafine Co-N-C ORR Catalysts with Embedded Co Quantum Dots.

M-N-C catalysts with optimized local and external structures offer great potential for replacing expensive and labile Pt-based catalysts for the oxygen reduction reaction (ORR) in fuel cells. Herein, we report a novel and facile strategy of synthesizing ultrafine ZIF-derived Co-N-C catalysts by precisely controlling the crystallization rate of ZIFs. The employment of meta-soluble Co-doped basic zinc acetate (Co-BZA), which shows a sustained-release effect in solvents, allows for the control of the solubility of Co-BZA in solvents. Detailed investigations suggest that the solubility of Co-BZA in the solvent is the key for governing the grain size of the resulting Zn/Co bimetallic ZIFs. Therefore, the self-assembly process between ligands and metal ions can be regulated by tuning the composition of mixed solvents, thus enabling rational tuning of the grain size of the resulting ZIFs. One-step pyrolysis of the ultrafine Zn/Co bimetallic ZIF precursor leads to Co and N co-doped carbon with an ultrafine grain size (termed UF Co-N-C). The Co centers that are uniformly distributed in the carbon matrix possess a quantum-dot-level grain size. Furthermore, this type of carbon nanohybrid exhibits a hierarchical pore structure, as well as a high surface area. When used as an ORR catalyst, the UF Co-N-C catalyst possesses high ORR activity (with an E1/2 of 0.9 V) that can rival 20 wt % commercial Pt/C (with an E1/2 of 0.835 V) in alkaline media. Notably, this catalyst also displays strong ORR performance similar to that of Pt/C in acidic media. The superior durability and methanol tolerance in both alkaline and acidic media for UF Co-N-C compared to Pt/C illustrate its great potential in replacing commercial Pt/C catalysts. The outstanding ORR performance of UF Co-N-C could be attributed to the simultaneous optimization of both external structures and active sites, demonstrating the effectiveness of this strategy in constructing ORR catalysts with controlled structures and desired functionalities.

Improving the mechanical characteristics of well cement using botryoid hybrid nano-carbon materials with proper dispersion

As a key barrier to ensure zonal isolation and wellbore integrity, well cement is required to have good flexibility and higher strength to withstand increasingly hostile downhole conditions. Nano-carbon materials are promising fillers to endow significant improvement in mechanical properties, anti-crack abilities, and durability of well cement. In this study, botryoid hybrid nano-carbon materials (BHNCMs) are introduced into wellbore cement at different concentrations (0.5% to 3% by weight of cement) for the first to formulate more flexible wellbore cement composites. The density, rheological properties, thickening time, fluid loss, and free fluid of the slurries of neat cement and cement composites were measured to evaluate the impact of the addition of BHNCMs on the workabilities of neat cement slurry. The triaxial compressive strength tests, which simulate more realistic downhole stress conditions, were performed to investigate the mechanical properties of hardened BHNCM cement composites. The results show that BHNCMs only need a simple preparation method to be effectively dispersed due to their self-assembled botryoid structure, which help manage the problem of agglomeration of nanocarbon materials. The addition of BHNCMs significantly improves the flexibility of oil well cement and enhances its strength. The optimal concentration of BHNCMs for successful improvement of well cement properties is found to be 1% by weight of cement (BWOC). At the optimum concentration, the compressive strength and flexibility of neat cement improve by 20%. The SEM-based microstructural analysis of cement composites showed various mechanical property enhancement mechanisms (filling effect, nano-core effect, bridge effect, and pinning effect) of BHNCMs.

Three-Dimensional Ni Foam-Supported CoO Nanoparticles/N-Doped Carbon Multilayer Nanocomposite Electrode for Oxygen Evolution

Metal–organic complex (MOC) multilayers are, for the first time, conformally constructed on Ni foam (NF) via a three-component sequential layer-by-layer (LbL) self-assembly approach and converted to three-dimensional (3-D) NF-supported interconnected CoO nanoparticles (NPs)/N-doped carbon nanohybrid multilayers via calcination. The obtained nanoarchitecture delivers an overpotential of 318 mV to achieve 10 mA cm–2 and a Tafel slope of 46.1 mV dec–1. This activity is superior to most reported oxygen evolution reaction (OER) catalysts, and even much better than those of Ir- and Ru-based ones measured under the same conditions (0.1 M KOH). Additionally, this electrode undergoes negligible potential and current change after 19.8 h chronopotentiometric measurement and 300 cyclic voltammetry cycles. The outstanding catalytic performance is mainly attributed to the ultrasmall and high-density CoO NPs embedded in N-doped carbon uniformly assembled on the 3-D substrate significantly increasing electrochemically accessible active sites and durability and the N-doped carbon greatly promoting intrinsic activity of CoO. This work not only creates 3-D highly tunable networked nanostructured electrodes with excellent durability for high-efficiency electrocatalysis but also develops a facile, economical, and extremely versatile strategy to controllably self-assemble conformal MOC-based multilayers with multifunctionality and superior performance on essentially any substrate at the molecular level for broad applications.

Synergistic interaction of graphene-amorphous carbon nanohybrid with thin metal loading for enhanced polymer electrolyte fuel cell performance and durability

In this communication, a synergistic interaction of the graphene- amorphous carbon (CG) nanohybrid support framework is configured, leading to excellent activity and stability in polymer electrolyte fuel cells. Graphene-amorphous carbon nanohybrid-Pt matrix is synthesized by a versatile chemical method. The optimum composition of CG nanohybrid with thin Pt loading of 50 μg cm−2 shows excellent catalytic activity. Besides, synergistic interaction between graphene and amorphous carbon nanohybrid results in enhanced stability of Pt and retains about 50% initial performance even after 5000 cycles.

PtNi Nanoparticles Loading on Sandwich-Like Hybrid Nanocarbon Support for Methanol Oxidation

A novel electrocatalyst, PtNi-graphene/carbon dots/graphene (PtNi/GCG), for methanol oxidation was prepared onto the glassy carbon electrode (GCE). The GCG hybrid nanocarbon support with sandwich-structure was dried onto GCE surface. Then, PtNi bimetallic nanoparticles were modified loaded on the GCG hybrid nanocarbon support via electrodeposition to obtain PtNi/GCG electrocatalyst. The as-prepared PtNi/GCG electrocatalyst was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and electrochemical analysis. The structure of PtNi/GCG shows that the PtNi nanoparticles were dispersed between the layered graphene. From electrochemical analysis, compared with Pt and PtNi/graphene catalysts, the as-prepared PtNi/GCG in this work has much better electrocatalytic properities towards methanol oxidation and shows better stability. The sandwich-structured electrocatalyst showed improved performance towards the methanol oxidation. The reason can be attributed to the synergistic effect between metals and the introduction of carbon dots between graphene layers. What’s more, carbon dots loading onto graphene layers effectively, which not only can increase the electrical conductivity, make available more active sites and reactive surface area, but also can enhance the dispersion of PtNi nanoparticles in the composite catalyst.

Photocatalytic degradation of antibiotic and hydrogen production using diatom-templated 3D WO3-x@mesoporous carbon nanohybrid under visible light irradiation

Synthesis of highly efficient 3D photocatalysts offers unique abilities for hydrogen production and chemical conversion to find a solution for energy shortage and environmental pollution issues. However, current strategies for production of ordered nanohybrid photocatalysts usually involve complex procedures and the use of expensive templates, which limit their practical applications. In this work, 3D WO3-x@mesoporous carbon photocatalyst was fabricated through one-pot evaporation-induced self-assembly (EISA) process using Cyclotella sp. as natural template. During heat-treatment, the precursor of carbon could partially reduce tungsten oxide under N2 atmosphere leading to the embedding of WO3-x in conductive mesoporous carbon structure. The diatom templated WO3-x@mesoporous carbon (DT-WO3-x@MC) nanohybrid exhibited high surface area (195.37 m2 g−1) and narrowed band gap (2.67 eV). Integration of tungsten oxide with mesoporous carbon and formation of oxygen vacancies enhanced the absorption of visible light using DT-WO3-x@MC and limited the recombination of electron-hole pairs. 98.7% of cefazolin (CFZ) degradation efficiency and 85.5% of total organic carbon (TOC) removal efficiency were observed within 90 and 180 min under visible light irradiation, respectively. Scavenger quenching tests and electron spin resonance (ESR) analysis demonstrated thatO2•− played a main role in photocatalysis. CFZ degradation pathway was proposed via identification of conversion intermediates using GC-MS analysis. Photocatalytic hydrogen production rates of the pure WO3 and the DT-WO3-x@MC nanohybrid were determined as 746 and 1851 μmol g−1 h−1, respectively. This study presented a way to develop a high-performance and stable photocatalyst using diatom frustules as natural template which works under practical conditions for environmental remediation and energy production.

Fabrication of amperometric sensor for glucose detection based on phosphotungstic acid–assisted PDPA/ZnO nanohybrid composite

Amperometric sensor of polydiphenylamine (PDPA)/phosphotungstic acid (PTA)/zinc oxide (ZnO) on glassy carbon (GC) nanohybrid composite electrode (GC/PDPA/PTA/ZnO) fabricated via facile electrochemical deposition method. The structural geometry and surface morphology were recorded by X-ray diffraction spectrometer (XRD) and scanning electron microscopy (SEM). Electro-catalytic properties and performances of nanohybrid composite were recorded by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) methods. PTA-assisted PDPA/ZnO-ME shows linear steady-state response towards glucose with superior sensitivity of 20.30 μA μM−1 cm−2, lowest detection limit 0.1 μM, and rapid response less than 2 s. The improved electro-catalytic performance towards glucose by GC/PDPA/PTA/ZnO is due to the combined existence of diphenoquinone diamine (DPDI2+) and phosphotungstic acid anion which provides a higher electro-catalytic active spots leads to more electron transport pathway for the oxidation of glucose. Interference analyses confirm the prepared nanohybrid sensor is best apt for glucose detection claims its practical biomedical application.

Feeding a Molecular Squid: A Pliable Nanocarbon Receptor for Electron-Poor Aromatics

A hybrid nanocarbon receptor consisting of a calix[4]arene and a bent oligophenylene loop (“molecular squid”), was obtained in an efficient, scalable synthesis. The system contains an electron-rich cavity with an adaptable shape, which can serve as a host for electron deficient guests, such as diquat, 10-methylacridinium, and anthraquinone. The new receptor forms inclusion complexes in the solid state and in solution, showing a dependence of the observed binding strength on the shape of the guest species and its charge. The interaction with the methylacridinium cation in solution was interpreted in terms of a 2:1 binding model, with K11 = 5.92(7) × 103 M–1. The solid receptor is porous to gases and vapors, yielding an uptake of ca. 4 mmol/g for methanol at 293 K. In solution, the receptor shows cyan fluorescence (λmaxem = 485 nm, ΦF = 33%), which is partly quenched upon binding of guests. Methylacridinium and anthraquinone adducts show red-shifted emission in the solid state, attributable to the charge-transfer character of these inclusion complexes.

An atomistic perspective on lithiation kinetics and morphological evolution in void-involved silicon/carbon nanohybrid

Void-involved silicon (Si)/carbon (C) nanohybrid has been considered as a promising anode material for the lithium ion batteries (LIBs). However, further optimizing the design and improving the performance of the void-involved Si/C electrodes still remain challenging. Here, the lithiation kinetics and morphological evolution in lithiated Si@CNT nanohybrids are investigated using large-scale atomistic simulations based on reactive force field (ReaxFF), and the effects of both size of C shell and contact mode between Si and C phase on the lithiation behavior are explored systematically. The simulation results quantitatively reveal that the constraint effect of C shell causes the Li capacity loss, and the barrier function of the void space retards the lithiation rate. Regulating the size of coating layer can mediate the constraint effect and barrier function. Furthermore, regulating the contact mode between Si and C phase to form an eccentric structure can effectively enhance the lithiation capacity (up to 10%) and lithiation rate at initial stage. Besides, the malleability and deformability of the lithiated a-LixSi phase are investigated at atomic-level. The findings not only provide theoretical rational for the lithiation mechanism of core-hollow shell nanohybrid, but also open avenues for optimizing the void-containing electrode design for high-performance LIBs.

Fabrication of lanthanum methanoate on sucrose-derived biomass carbon nanohybrid for the efficient removal of arsenate from water

Herein, we have designed and synthesized a metal-organic framework (MOF)-like lanthanum–methanoate (LaMe) nanocomplex for the remediation of arsenate (AsO43−) from aqueous environment, in which AsO43− replaces the formic acid from LaMe through ligand exchange, partially disintegrates the crystal lattice, and is re-precipitated as LaAsO4. Consequently, the sucrose-derived biomass carbon (SBC) was utilized as supporting material to develop nanohybrid of LaMe@SBC to inhibit the solubility of lanthanum from LaMe, and enhance the adsorption ability towards AsO43− from water. The maximum adsorption densities of AsO43− on SBC and LaMe were (0.059 and 0.793) mmol/g, respectively. On the other hand, the synergistically re-constructed LaMe@SBC nanohybrid possesses AsO43− adsorption density of 0.918 mmol/g at 25 °C. The studies, including contact time, solution pH, competitive anions, and initial AsO43− concentration, were optimized for maximum AsO43− removal. The adsorption density of the LaMe@SBC for AsO43− removal was pH-dependent, and possesses the maximum adsorption density at pH (4.0 and 5.0); moreover, the removal process was highly selective in the presence of common co-existing anions, except PO43− ion. The adsorption isotherm and kinetics of the LaMe@SBC nanohybrid closely fitted the Langmuir isotherm and pseudo-second-order kinetic models, respectively. The surface interactions among the LaMe@SBC nanohybrid and AsO43− were revealed through FTIR and PXRD analyses. The adsorption of AsO43− on the LaMe@SBC nanohybrid was primarily a chemisorption, namely ligand exchange and electrostatic interactions. The results reported in this research work highlight the feasibility of the LaMe@SBC nanohybrid as a real adsorbent for the removal of AsO43− from aqueous environment.

Eco-friendly magnetic activated carbon nano-hybrid for facile oil spills separation

This work focuses mainly on environmental concern and protection through providing beneficial use of waste biomass from water hyacinth to produce economical nano-magnetic adsorbent material-efficient for facile oil spill separation via an external magnetic field. The water hyacinth roots showed higher oil spills adsorption affinity of 2.2 g/g compared with 1.2 g/g for shoots. Nano-activated carbon was successfully extracted from the roots of water hyacinth after alkaline activation and followed by zinc chloride treatment before its carbonization. Nano-magnetite was induced into the activated carbonized nanomaterials to synthesized nano-magnetic activated carbon hybrid material (NMAC). X-ray diffraction elucidated the crystalline nature of both extracted activated carbon from water hyacinth and its magnetic hybrid material. Scanning electron microscopic micrographs implied the nano-size of both prepared activated carbon and the magnetite hybrid materials. The magnetic properties of the fabricated nano-magnetic activated carbon were evaluated using the vibrating sample magnetometer. The magnetic nano-hybrid material recorded a maximum oil adsorption affinity of 30.2 g oil/g. The optimum oil spill of 80% was established after 60 min in the presence of 1 g/L of magnetic nano-hybrid. The magnetic nano-hybrid material that absorbs oil spills was separated from the treatment media easily using an external magnetic field.

Nitrogen-doped carbon nanotube-encapsulated nickel nanoparticles assembled on graphene for efficient CO2 electroreduction

Exploring 3D hybrid nanocarbons encapsulated with metal nanoparticles (NPs) are recently considered as emerging catalysts for boosting CO2 electroreduction reaction (CRR) under practical and economic limits. Herein, we report a one-step pyrolysis strategy for fabricating N-doped carbon nanotube (CNT)-encapsulated Ni NPs assembled on the surface of graphene (N/NiNPs@CNT/G) to efficiently convert CO2 into CO. In such 3D hybrid, the particle size of Ni NPs that coated by five graphitic carbon layers is less than 100 nm, and the amount of N dopants introduced into graphene with countable CNTs is determined to 7.27 at%. Thanks to unique CNT-encapsulated Ni NPs structure and N dopants, the achieved N/NiNPs@CNT/G hybrid displays an exceptional CRR activity with a high Faradaic efficiency of 97.7% and large CO partial current density of 7.9 mA/cm2 at −0.7 V, which outperforms those reported metallic NPs loaded carbon based CRR electrocatalysts. Further, a low Tafel slope of 134 mV/dec, a turnover frequency of 387.3 CO/h at −0.9 V, and tiny performance losses during long-term CRR operation are observed on N/NiNPs@CNT/G. Experimental observations illustrate that the Ni NPs encapsulated by carbon layers along with N dopants are of great importance in the conversion of CO2 into CO with high current density.

Structural modal identification and health monitoring of building structures using self-sensing cementitious composites

Recently self-sensing cementitious composite has demonstrated its strong potentiality for structural health monitoring of civil infrastructures because of its low-cost, long-term stability and compatibility with concrete structures. In this paper, we propose novel hybrid nanocarbon materials engineered cement-based sensors (HNCSs) with high-sensitivity, which are fabricated with self-sensing cementitious composites containing electrostatic self-assembled CNT/NCB composite fillers. The mechanical property and sensing performance of the HNCSs are pre-characterized under static and dynamic compressive loadings. The HNCSs are then integrated into a five-story building model via custom-made clamps to verify the feasibility for dynamic response measurements. Results show that the developed sensors have satisfactory mechanical property and excellent pressure-sensitive reproducibility and stability. With clamps holding on the building model, the HNCSs perform satisfactorily under sinusoidal excitations in the frequency range from 2 to 40 Hz. In addition, the modal frequencies and their changes of the building model caused by ‘damage’ simulated through adding additional masses identified by the HNCSs are favorably consistent with the counterparts acquired by accelerometers and strain gauges, indicating that the developed HNCSs have great potential for structural modal identification and damage detection applications.