CuO Nanotubes Research Articles

Enhancing the heat transfer in CuO-MWCNT oil hybrid nanofluid flow in a pipe

In this study, three-dimensional steady-state laminar flow simulations were conducted in a horizontal pipe using CuO and multi-walled carbon nanotubes (MWCNT) nanoparticles with engine oil as the base fluid. Various nanoparticle volume fractions were examined under a constant heat flux boundary condition applied to the pipe wall. The main goal was to assess and compare the effects of different nanoparticle volume concentrations, including CuO and MWCNT in ratios of 1:1 and 1:2, on convective heat transfer. A second-order discretisation method was employed for solving the equations, and the SIMPLE algorithm was used for pressure–velocity coupling in the CFD code. The study focused on the impact of nanoparticle volume fraction on the convective heat transfer coefficient and the Nusselt number at a Reynolds number of 750. The findings indicate that increasing the nanoparticle volume fraction enhances both the convective heat transfer coefficient and the Nusselt number, with MWCNT having a more pronounced effect compared to CuO. Specifically, adding 2% CuO increases the heat transfer coefficient by 65%, while a mixture of 1% CuO and 1% MWCNT boosts it by 75%. The thermal boundary layer thickness also grows with higher nanoparticle concentrations, with 1% CuO and 3% CuO increasing the thickness by 1.5% and 3.6%, respectively. A formula for the thermal boundary layer thickness in CuO-oil nanofluids is provided based on volume fraction, and a scale analysis of the average heat transfer coefficient confirms that the simulation results are consistent with this analysis.

Room temperature hydrogen sulfide gas detection using copper oxide nanotube/indium tin oxide nanoparticle heterojunctions

Various copper oxide nanotube/indium tin oxide (CuO/ITO) nanocomposite-based chemiresistive gas sensors were fabricated and tested toward hydrogen sulfide (H2S) in the presence and absence of ultra-violet (UV) light excitation at room temperature. Among these different combinations, 60:40 wt.% of CuO:ITO showed the highest sensing performance toward H2S gas (i.e., sensor response (S) = 5.7 toward 40 ppmm (parts per million by mass) H2S gas), which is ̴5.7 times higher than pristine CuO and ITO counterparts. The enhancement in the gas sensing performance by mixing ITO and CuO nanostructures might be due to the formation of p/n heterojunction between ITO nanoparticles and CuO nanotubes. The low limit of detection (LLOD) of 500 ppbm (part per billion by mass) of S = 1.2 was experimentally achieved by photo exciting sensing materials using 400 nm UV light. This might be attributed to the faster adsorption of H2S molecules and higher carrier concentration under light illumination. These sensors also maintained good H2S sensing performance in the presence of water vapors which makes these sensors suitable for practical application. This work paves a way to fabricate low-power H2S gas sensors by eliminating heaters.

Study on heat transfer and pressure drop characteristics for nanofluids in microchannel heat exchangers

The microchannel heat exchanger (MCHE) is considered the next-generation heat exchanger owing to its high-performance thermal management systems and fabrication processes. The MCHE is used in many cooling applications, such as x ray medical devices, high-power microelectronics, and high-heat flux devices. Comprehensive exploration of different nanofluids, their concentrations, and impacts on pressure drop and heat transfer within the context of MCHEs was the main focus of the current study. The experiments were conducted at Reynolds numbers ranging from 100 to 500 for laminar flow. Additionally, nanoparticles (np) such as Al2O3, CuO, and carbon nanotubes (CNT) were added to de-ionized water at weight percentages of 0.01, 0.03, and 0.05. The results indicated that heat transfer significantly increased at a particle concentration 0.05 by wt. % for all nanofluids (nf). Furthermore, at a particle of 0.05 by wt. %, the heat transfer of the CNT-based nf increased by 37%, whereas those of the Al2O3- and CuO-based nf increased by 24.01% and 6.23%, respectively. The nanofluid pressure drop (PD) increases with an increase in the Reynolds number owing to the increase in the viscosity of the liquid compared to de-ionized water (base fluid) and requires more pumping power.

Comparison and evaluation of energetic and exergetic performance of an evacuated tube solar collector using various nanofluid

There is a growing interest in renewable energy sources cause the worsening impact of fossil fuel development and abuse on the ecological environment. Solar collectors are major facilities that utilize solar energy, many studies and techniques have been employed to increase the efficiency of the collectors. This paper aims to evaluate the thermal performance of an evacuated tube solar collector(ETSC) in the solar thermal system by using Al2O3, CuO, Fe3O4 and Multi-walled carbon nanotube(MWCNT) nanofluid as working fluids. An evaluation approach for the energy, exergy and entropy of ETSC were proposed. Furthermore, the energy gained and stored by nanofluid in the solar collector was also been studied. The ETSC shown highest energy and exergy efficiency when the 0.01 vol%-MWCNT nanofluid was used which was 33.1% higher than that of water, and it was the same situation of exergy efficiency while the highest was 3.17 under the optimum situation. In addition, the energy gained by 0.01 vol%-MWCNT nanofluid showed the highest potential of energy absorption than other nanofluid, the maximum exergy destruction and entropy generation were achieved when water was used as working fluid of solar collector while the lowest were observed when MWCNT nanofluid with 0.01 vol% was used. Compared to normal working fluid in the ETSC, the use of nanofluid with high thermal conductivity can save more fossil fuels and coals which have a positive effect on protecting the environment.

Surfactant‐Mediated Synthesis of Novel Mesoporous Hollow CuO Nanotubes as an Anode Material for Lithium‐Ion Battery Application

AbstractIn this work, the hollow mesoporous CuO nanotubes are synthesized using a surfactant‐assisted soft template approach. It is believed that the surfactant used during the synthesis provides a skeleton for the rearrangement of nanoparticles, resulting in the formation of hollow nanotubes. Furthermore, the sample becomes mesoporous during the calcination at 500 °C due to the removal of the surfactant template. On the other hand, the porous nanostructure efficiently improves the reaction kinetics of the electrode material, which offers excellent electrochemical performance. The obtained hollow mesoporous CuO nanotube electrode manifests high Li‐ion storage such as ∼253 mAh g−1 at 1 C and 118 mAh g−1 at 3 C after 150 cycles. It is significant to highlight that the current synthesis process is straightforward, affordable, time‐efficient and environment friendly as compared to tedious physical approaches. In addition, the proposed strategy in this work also demonstrates a window for the development of new advanced nanomaterials for post‐lithium‐ion battery applications.

Preparation of CuO@humic acid@carbon nanotube composite material using humic acid as a coupling agent and its lithium-ion storage performance.

The conventional Li-ion battery composite electrode material composed of CuO and carbon nanotubes (CNTs) suffer from poor contact between CuO and CNTs. This results in high electrode resistance and poor electrochemical performance. To solve this problem, CuO@humic acid (HA) @CNT anode material with cross-linked network structure was generated by linking CuO and CNT with HA as a coupling agent. For comparison, CuO@HA or CuO@CNT were also prepared in the absence of CNT or HA, respectively. The results showed that CuO@HA@CNT had lower charge transfer resistance, higher conductivity, lithium-ion diffusion coefficient, specific capacity, and rate capability than CuO@HA and CuO@CNT. The specific capacity of the CuO@HA@CNT electrode was significantly better than that of the composite electrode materials of CuO and CNT, which have been prepared by scientists using various methods. Due to the introduction of HA, not only was the uniformly distributed flower-like CuO obtained, but also the specific capacity and rate capability of the electrode material were substantially improved. This study thus provides a good strategy to optimize the capability of transition metal oxide lithium-ion anode materials.

Metal-organic framework-assisted Co3O4/CuO@CoMnP with core-shell nanostructured architecture on Cu fibers for fabrication of flexible wire-typed enzyme-free micro-sensors

Flexible fiber-based sensors have recently received increasing interest for real-time monitoring personal health, owing to their small size, high flexibility, lightweight, and application potentials in next-generation wearable electronics. Herein, we report a flexible wire-typed micro-sensor based on CoMnP@Co3O4/CuO core–shell nanohybrid array on 1D Cu wire substrate for sensitive detection of glucose. The synthesis process involves in-situ growth of ZIF-67 rhombic dodecahedron on the surface of CuO nanotubes, followed by thermal annealing and electrodeposition of CoMnP nanoparticles to form core–shell nanostructured architectures. Benefiting from desirable hybrid nanostructures, the as-made binder-free fiber microelectrode exposes more electroactive sites for transport of ions and electrons during the catalytic process and provides strong adhesion between electroactive species and metal fiber substrate. As a glucose sensor, the CoMnP@Co3O4/CuO fiber microelectrode displays favorable analytical properties, including two linear dynamic ranges of 0.001 mM – 0.55 mM and 0.55 mM – 3.03 mM with the sensitivities of 2445 μA mM−1cm−2 and 1774 μA mM−1cm−2, respectively, fast response time (1.62 s), excellent selectivity toward glucose at the presence interfering substances, and a low detection limit of 11.42 μM (S/N = 3). Moreover, the proposed wire-typed micro-sensor was successfully applied for measurement of glucose in human blood serum and saliva samples. Taking advantage of the versatility of 1D metal fiber current collector, MOF-assisted strategy and transition metal phosphides, the presented protocol here can be extended to the construction of other wearable and implantable sensing micro-devices.

Carbon-Based Ternary Nanocomposite: Bullet Type ZnO-SWCNT-CuO for Substantial Solar-Driven Photocatalytic Decomposition of Aqueous Organic Contaminants.

A facile two-step synthesis of ternary hetero-composites of ZnO, CuO, and single-walled carbon nanotubes (SWCNTs) was developed through a recrystallization process followed by annealing. A series of nanocomposites were prepared by varying the weight ratio of copper(II) acetate hydrate and zinc(II) acetate dihydrate and keeping the weight ratio of SWCNTs constant. The results revealed the formation of heterojunctions (ZnO-SWCNT-CuO, ZSC) of three crystal structures adjacent to each other, forming a ternary wurtzite-structured nanoparticles along with defects. Enhanced charge separation (electron-hole pairs), reduced band gap, defect-enhanced specific surface area, and promoted oxidation potential were key factors for the enhanced photocatalytic activity of the ternary nanocomposites. OH• radicals were the main active species during dye degradation, and O2-• and h+ were also involved to a lesser extent. A type II heterojunction mechanism approach is proposed based on the charge carrier migration pattern. Among the synthesized nanocomposites, the sample prepared using copper(II) acetate hydrate and zinc(II) acetate dihydrate in a 1: 9 ratio (designated a ZSC3) showed the highest photocatalytic activity. ZSC3 achieved 99.2% photodecomposition of methylene blue in 20 min, 94.1% photodecomposition of Congo red in 60 min, and 99.6% photodecomposition of Rhodamine B in 40 min under simulated sunlight. Additionally, ZSC3 showed excellent reusability and stability, maintaining 96.7% of its activity even after five successive uses. Based on overall results, the ZSC sample was proposed as an excellent candidate for water purification applications.

Autophagy and lipid droplets are a defense mechanism against toxic copper oxide nanotubes in the eukaryotic microbial model Tetrahymena thermophila

The widespread use of inorganic nanomaterials of anthropogenic origin has significantly increased in the last decade, being now considered as emerging pollutants. This makes it necessary to carry out studies to further understand their toxicity and interactions with cells. In the present work we analyzed the toxicity of CuO nanotubes (CuONT) in the ciliate Tetrahymena thermophila, a eukaryotic unicellular model with animal biology. CuONT exposure rapidly induced ROS generation in the cell leading to oxidative stress and upregulation of genes encoding antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), metal-chelating metallothioneins and cytochrome P450 monooxygenases. Comet assays and overexpression of genes involved in DNA repair confirmed oxidative DNA damage in CuONT-treated cells. Remarkably, both electron and fluorescent microscopy revealed numerous lipid droplets and autophagosomes containing CuONT aggregates and damaged mitochondria, indicating activation of macroautophagy, which was further confirmed by a dramatic upregulation of ATG (AuTophaGy related) genes. Treatment with autophagy inhibitors significantly increased CuONT toxicity, evidencing the protective role of autophagy towards CuONT-induced damage. Moreover, increased formation of lipid droplets appears as an additional mechanism of CuONT detoxification. Based on these results, we present a hypothetical scenario summarizing how T. thermophila responds to CuONT toxicity. This study corroborates the use of this ciliate as an excellent eukaryotic microbial model for analyzing the cellular response to stress caused by toxic metal nanoparticles.

Self‐Supported CuO In‐Situ‐Grown on Copper Foil as Binder‐Free Anode for Lithium‐Ion Batteries

AbstractTransition metal oxides as anode materials for lithium‐ion batteries (LIBs) possess the advantages of high specific capacity and abundance. However, most reported transition metal oxides based active anode materials were coated on the copper current collector with the addition of inactive polymer binder and conductive agents, resulting in low utilization of active substances. To solve this problem, nanostructured CuO with different morphologies (CuO bunches, CuO nanosheets, CuO nanotubes) were in‐situ grown on the copper current collectors via a simple wet chemical oxidation method. The as‐obtained CuO@Cu foils were used directly as anode for LIBs. CuO nanotubes exhibited excellent electrochemical performance and sustained a reversible discharge specific capacity of 798 mA h g−1 after 60 cycles at 100 mA g−1. At current density of 1000 mA g−1, a high specific capacity of 758 mA h g−1 can be obtained after 200 cycles. The satisfying electrochemical performances of the CuO nanotubes anode indicated that a stable composite structure of CuO@Cu foils was achieved in the binder free electrode. This work demonstrated the feasibility of this binder free strategy in the development of electrode materials for high performance lithium‐ion batteries design.

Synthesis of dual-functional CuO nanotubes for high-efficiently photoelectrochemical and colorimetric sensing of H2O2

Among one-dimensional nanostructures, copper oxide nanotubes (CuO NTs) have aroused wide attention due to their prominent performance in electronic, optical and energy conversion devices. However, the lack of suitable synthetic methods limits its large-scale production and broad application. Here, a new method for preparing well-dispersed CuO NTs with simple operation, mild conditions and low cost was established by integrating the synergy effect of H+ corrosion with the protection of CH3COO− and surfactant. Different surfactants were applied to regulate the synthetic process and polyvinylpyrrolidone-protected CuO NTs (PVP-CuO NTs) owned the best uniform morphology and dispersibility. The synthesis mechanism was deeply investigated to provide guidance for the synthesis of other oxide nanotube structures. As an excellent semiconductor material, CuO NTs can be excited to produce multiple electron-hole pairs under light irradiation, thus catalyzing the reduction of H2O2. CuO NTs modified photocathode realized photoelectrochemical sensing of H2O2 in the range of 1 μM-1 mM. Interestingly, the prepared CuO NTs exhibited wonderful mimic enzyme properties, providing the possibility of colorimetric sensing and point-of-care detection. The colorimetric sensor for H2O2 detection had a linear relationship from 2 μM to 150 μM with a detection limit of 0.62 μM. The successful construction of the two sensing modes not only demonstrated the excellent performance of multifunctional CuO NTs, but also indicated its great promise in practical application.

Impacts of typical engineering nanomaterials on the response of rhizobacteria communities and rice (Oryza sativa L.) growths in waterlogged antimony-contaminated soils

The combined eco-risks of Sb (widely presented in soils, especially nearing mining areas) and the engineering nanomaterials (ENMs) (applied in agriculture and soil remediation) still remain uncovered. The current study investigated the impacts of single and combined exposure of CuO, CeO2 nanoparticles (NPs) and multi-walled carbon nanotube (MWCNTs) with Sb on rice growths and rhizosphere bacterial communities. The results showed that co-exposure of CuO NPs (0.075 wt%) with Sb (III) posed the most adverse impacts on root biomass and branches (up to 66.59% and 70.00% compared to other treatments, respectively). Treatments containing MWCNTs showed insignificant dose-dependent effects, while CeO2 NPs combined with Sb (III) showed significant synergistic stimulating effects on the fresh weights of root and shoot, by 68.30% and 73.48% (p < 0.05) compared to single Sb exposure, respectively. The rice planting increased the percentage of non-specifically sorbed Sb in soils by 1.50–14.49 than the no-planting stage. Analysis on microbial communities revealed that co-exposure of CuO NPs with Sb (III) induced the greatest adverse impacts on rhizobacteria abundances and community structures at both phylum and genus levels. Therein, significant decrease of Bacteroidetes, Acidobacteria and increase of Firmicutes abundance at the phylum level were observed. This study provided information about the risks of different ENMs released to Sb-contaminated soils under flooded condition on both crops and bacterial communities.

Template-assisted electrodeposited cupric oxide nanotubes and hierarchical nanospikes for tailoring electrode-electrolyte interfacial charge transfer

Morphological modification in materials aids multi-channel electron access sites for easier electrolyte ion access for many electrochemical devices including energy storage devices. Controlled synthesis of such multichannel morphologies of metal oxides offers significant challenges. Herein, we report a template-assisted electrodeposition technique for the synthesis of Cu nanowires, which are transformed into either CuO nanotubes by controlled annealing or CuO hierarchical nanospikes using a simple hydroxyl ion impregnation technique and subsequent annealing. These materials are tested as electrodes in charge storage systems in 6 M KOH electrolyte in a three-electrode system; both electrodes have shown battery-type charge storage behaviour. Despite the chemical similarity between the two materials, the CuO nanospikes electrodes showed improved charge transport between electrode-electrolyte interface compared to the CuO nanotubes. With the cost-effectiveness, easy availability, and multi-channel morphology of CuO nanospikes along with the promising performance of the electrode in a three-electrode system, the present research offers future potential in developing low cost and high performing energy storage devices.

Enhanced thermal management by introducing nanoparticle composite phase change materials for cooling multiple heat sources systems

In this paper, paraffin mixed with nanoparticles Al2O3, CuO, and multi-walled carbon nanotubes (MWCNTs) were prepared for cooling multiple heat sources. For thermal management of heat sources, performances of the composite phase change materials (PCMs) were investigated at different heating power. Enhanced performance in terms of heat sources temperature, temperature difference between two heat sources, and thermal resistance was experimentally tested and analyzed at various mass fractions of nanoparticle and various power levels. It is found that by using 1.0 wt% Al2O3 composite PCMs the minimal thermal resistance is achieved at the range from 0.63 °C/W to 0.71 °C/W for all power levels, and the heat storage and heat conduction of the presented composite PCMs are enhanced as well as the melting ratio. At 8 W power level, the temperature of the heat source 1 for 1.0 wt% Al2O3 composite PCMs decreases by 17.4% compared to that for pure paraffin.

Toxicogenomic Profiling of 28 Nanomaterials in Mouse Airways.

Toxicogenomics opens novel opportunities for hazard assessment by utilizing computational methods to map molecular events and biological processes. In this study, the transcriptomic and immunopathological changes associated with airway exposure to a total of 28 engineered nanomaterials (ENM) are investigated. The ENM are selected to have different core (Ag, Au, TiO2, CuO, nanodiamond, and multiwalled carbon nanotubes) and surface chemistries (COOH, NH2, or polyethylene glycosylation (PEG)). Additionally, ENM with variations in either size (Au) or shape (TiO2) are included. Mice are exposed to 10 µg of ENM by oropharyngeal aspiration for 4 consecutive days, followed by extensive histological/cytological analyses and transcriptomic characterization of lung tissue. The results demonstrate that transcriptomic alterations are correlated with the inflammatory cell infiltrate in the lungs. Surface modification has varying effects on the airways with amination rendering the strongest inflammatory response, while PEGylation suppresses toxicity. However, toxicological responses are also dependent on ENM core chemistry. In addition to ENM‐specific transcriptional changes, a subset of 50 shared differentially expressed genes is also highlighted that cluster these ENM according to their toxicity. This study provides the largest in vivo data set currently available and as such provides valuable information to be utilized in developing predictive models for ENM toxicity.

Thermo-Hydraulic Performance Enhancement of Liquid He Based Cryogenic Nanofluid Flow in Laminar Region Through Rectangular Plate Fin Heat Exchangers -A Numerical Study

Cryogenic applications are increasing in recent times with the advancement of technology. This research work is focused to improve performance of cryogenic fluid in compact heat exchangers. Nanoparticles with high thermal conductivity is mixed with the cryogenic fluid to improve the thermo-hydraulic efficiency of the heat transfer fluid used in the compact heat exchangers. Liquid He has been used as base fluid and its performance has been compared using nanoparticles CuO, Al2O3, Fe3O4 and Single Wall Carbon Nanotube (SWCNT). A numerical analysis has been done in the laminar range of flows in a PFHE. Comparison of the nanofluids at cryogenic temperature is compared with heat transfer performance parameter Colburn j-factor and pressure drop performance parameter Fanning’s friction factor(f). It has been found that around 15-30% enhancement of thermal performance is achieved with nanoparticles in comparison to liquid He without any nanoparticles. It has also been observed that there is an improvement of j/f 1/3 factor representing heat transfer enhancement without much increasing pumping pressure.

Thermal Conductivity Enhancement via Synthesis Produces a New Hybrid Mixture Composed of Copper Oxide and Multi-walled Carbon Nanotube Dispersed in Water: Experimental Characterization and Artificial Neural Network Modeling

Nanofluid is a solid–fluid mixture. By using one solid nanoparticle or one fluid, mono-nanofluid (MN) forms, and by using two solid nanoparticles (NPs) or two fluids, hybrid-nanofluid (HN) forms. For this study, for MN, copper oxide (CuO) and for HN, two solids, which are CuO and multi-walled carbon nanotube (MWCNT) were dispersed in base fluid which is water. After nanofluid preparation, thermal conductivity was measured, and the achievements were numerically modeled. After that, XRD–EDX were performed for the phase-structural analysis. Then, FESEM was examined for NPs-microstructural study. Thermal conductivity (TC) of MN and HN were investigated at 0.2 % to 1.0 % volume fractions (Vf) in 25 °C to 50 °C temperature (T) ranges. Thermal conductivity enhancements of 19.16 % and 37.05 % were seen at the utmost Vf and T for mono-nanofluid and hybrid-nanofluid, respectively. New correlations have been presented with R2 = 0.9, and also Artificial Neural Network (ANN) has been done with R2 = 0.999. For the presented correlation, 0.86 %, and 0.51 % deviations, and for the trained model, 0.41 % and 0.51 % deviations were estimated for mono-nanofluid and hybrid-nanofluid, respectively. As a final result, by adding MWCNT to CuO–H2O mixture, thermal conductivity is raised by 17.89 %, and the hybrid-nanofluid has acceptable heat-transfer capability.

Performance of a Solar Absorption Cooling System Using Nanofluids and a Membrane-Based Microchannel Desorber

In this work, the performance of a single effect absorption cooling system fed by solar thermal energy is evaluated. The absorption chiller includes a membrane-based microchannel desorber using three types of nanoparticles: Al2O3, CuO, or carbon nanotubes (CNT). Correlations available in the open literature to calculate the thermal conductivity of nanofluids are reviewed. Using experimental data for the water-lithium bromide solution (H2O-LiBr) with Al2O3 and CNT nanoparticles, the most appropriate correlation for thermal conductivity is selected. Nanofluid properties are evaluated using a concentration of nanoparticles of up to 5% in volume. The largest increase in the desorption rate (7.9%), with respect to using pure H2O-LiBr solution, is obtained using CNT nanoparticles and the maximum concentration of nanoparticles simulated. The performance of the chiller is evaluated and the daily solar coefficient of performance (SCOP) for the solar cooling facility is obtained. The best improvement with respect to the conventional system (without nanoparticles) represents an increase in the cooling effect of up to 6%. The maximum number of desorber modules recommended, always lower than 50, has been identified.

Progress of MWCNT, Al 2 O 3 , and CuO with water in enhancing the photovoltaic thermal system

Hybrid photovoltaic thermal system is an effective method to convert solar energy into electrical and thermal energy. However, its effectiveness is widely affected due to the high temperature of photovoltaic panel, and it can be minimized by employing nanofluids to the PV/T systems. In this research, the effect of various nanoparticles on the PV/T systems was studied experimentally. The nanofluids Al2O3, CuO, and multiwall carbon nanotube (MWCNT) were dispersed with water at different volume fractions of 0, 0.5, 1, 2.5, and 5 (vol%) using ultrasonication process. The effect of nanomaterials on viscosity and density was classified. All tests were carried out in an outdoor laboratory setup for calibrating the PV temperatures, thermal conductivity, electrical power, electrical efficiency, and overall efficiency. In addition, the energy analyses were also made to estimate the loss of heat owing to the nanofluids. Results show that use of the nanofluid increased the electric power and electrical efficiency of PV/T compared with water. Furthermore, MWCNT and CuO reduced the cell temperature by 19%. Consequently, the nanofluids MWCNT, Al2O3, and CuO produced the impressive values of 60%, 55%, and 52% increase in an average electrical efficiency than conventional PV. Particularly, the MWCNT produced superior results compared with other materials. It is evidently clear from the result that the introduction of the nanofluid increases the thermal efficiency without adding any extra energy to the system. Moreover, insertion of Al2O3, CuO, and MWCNT on PV/T system increases the exergy efficiency more than conventional PV module.

Economical, green and rapid synthesis of CDs-Cu2O/CuO nanotube from the biomass waste reed as sensitive sensing platform for the electrochemical detection of hydrazine

Reeds live widely in swamp and wetland and have an important ecological balance functions in environmental protection. However, the use of reeds is not effectively. The carbon dots (CDs) have been developed as the family of 0D nanocarbon materials and have all the advantages of the carbon family. In this work, we prepared CDs via hydrothermal method using reed. It is surprising that the reed-derived CDs are an effective reducing agent. A highly catalytically active composite material CDs-Cu2O/CuO was synthesized using economical, green, one-step ultrasonic method and used for the detection of hydrazine. The electrochemical detection of hydrazine was investigated by cyclic voltammetry. The result shows that the CDs-Cu2O/CuO exhibited good electrocatalytic activity for the oxidation of hydrazine. The fabricated sensor presented a wide linear range from 0.99 μM to 5903 μM and a detection limit of 0.024 μM. In addition, the CDs-Cu2O/CuO exhibited good sensitivity, stability and repeatability. Therefore, the CDs-Cu2O/CuO provides a new idea for the utilization of reed and low-cost electrocatalytic nanocomposite.