In this work, carbon nanotubes (CNTs) synthesized by low-pressure chemical vapor deposition (LPCVD) on silicon (Si), quartz, gallium arsenide (GaAs), and gallium nitride (GaN) substrates are examined for their growth, field emission (FE), and gas sensing performance. Field emission scanning electron microscopy (FESEM) and Raman spectroscopy were used to examine the CNTs surface morphology, alignment, and structural quality of as prepared samples. The results showed notable substrate-dependent differences in growth behavior. Because of their dense, vertically aligned structure, which facilitates effective electron transport, FE experiments showed that CNTs grown on Si substrates have a superior electron emission property which is very low turn on 0.9 V/µm threshold 1.175 V/µm and high current density 13.56 mA/cm2 as compared to other. On the other hand, CNTs emitting on GaN substrates had better turn-on properties but a somewhat lower emission current. Different substrate-dependent sensing behavior was found in gas sensing investigations toward ammonia (NH₃), with CNTs on GaN substrates exhibiting quicker response 6s and recovery 12s than those on other substrates growing CNTs. The findings demonstrate how important substrate engineering is for modifying the morphology and functional performance of CNTs. This comparative analysis offers fresh perspectives on how to optimize CNTs-substrate systems for specific uses in gas sensing and field emission devices.

In this study, the electron field emission properties of carbon nanotubes (CNTs) were enhanced by decorating them with indium (In) nanoparticles. The structural and morphological characteristics of pristine and In-decorated CNTs were analyzed using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). Field emission parameters such as turn-on field (Eto), threshold field (Eth), field enhancement factor (β), and maximum current density (Jmax) were thoroughly investigated. Results revealed that In decoration reduced the Eto from 1.25 V/μm to 1.0 V/μm and decreased the Eth from 1.4 to 1.36 V/μm, indicating lower voltage requirements for electron emission. The field enhancement factor (β) significantly increased from 2730 to 5230, while the Jmax rise from 238.33 to 333.3 μA/cm2. These improvements demonstrate that In-decorated CNTs exhibit superior electron emission performance, making them promising for advanced electron emission applications.

This study examined a room temperature operative, highly sensitive, stable, and selective PANI ammonia (NH3) gas sensor using multiwalled carbon nanotubes (MWCNTs) and copper nanocomposites (Cu). The silicon substrate was coated with the sensing materials using the drop casting technique. To synthesize PANI, PANI@Cu@MWCNT nanocomposites chemical polymerisation method and ultrasonication techniques were used. In comparison to three PANI nano-composite sensor, which demonstrated sensing responses of 18%, 28%, and 43%, respectively, the PANI@Cu3@MWCNT3-based sensor demonstrated a greater sensing response of 116% under the room temperature conditions of NH3 (100 ppm). The resistance variation of all the sensors is 62 kΩ, 78 kΩ, 89 kΩ, and 90 kΩ respectively. The PANI@Cu3@MWCNT3 based sensor exhibited excellent results in term of resistance (90 kΩ). The stability, response time (10 s), and recovery time (13 s) of PANI@Cu2@MWCNT2 is measured and has better results in terms of time than all other sensors. Pure PANI nano-composite sensor has shown the sensing response of 18%, resistance variation of 62 kΩ, response time (45 s), recovery time (48 s) respectively. The sensing materials were characterized using FTIR, XRD, EDX, and FESEM techniques. PANI and PANI@Cu@MWCNT nanocomposites' gas sensing capabilities were examined using a Keithley 6514 multimeter.

In this work, the fabrication and comparison of distinct types of multi-walled carbon nanotube-based gas sensing devices on N type (100) silicon substrates for the detection of low ammonia concentrations are reported. Every measurement was made at room temperature. The whole process was tested at 10 ppm of ammonia gas. We have noticed the characteristics of fast response/recovery time (1-9 s) in pristine and (1-5 s) in Manganese metal (Mn) nanoparticles (99.99% purity) decorated MWCNT. The high-quality sensor response of roughly 82% has been found in pristine,177% in 2 min decorated, 73% in 4 min decorated and 130% in 6 min decorated respectively. The sensitivity of the as prepared samples comes to be 14% for the pristine, 35%, 37%, and 43% for rest of the sensors on percentage bases respectively. 75%-85% recovery was attained based on the obtained sensor response graph. The stability was also measured for a period of 7 days at constant concentration. A Keithley 6514 source meter was used for the resistance variation measurements. FESEM (Gemini 500), Raman spectroscopy (Renishaw), XRD, EDS and FTIR have been used to examine the different morphologies of the as prepared materials.

In vacuum and display electronics, field emission (FE) electron sources are becoming increasingly common because of their low energy consumption, high efficiency, and fast reaction when compared to thermionic emission sources. Since the 1990s, carbon nanotubes (CNTs) have emerged as promising electron field emitters because of their small size, high aspect ratio, chemical stability, and excellent electrical and thermal conductivity. Recent studies show that CNT-based FE exhibits superior properties in practical applications and may replace conventional thermionic emission in various sectors. This paper offers a thorough analysis of the latest advancements in CNT field emitters, examining the factors influencing their performance, including type (single-walled versus multi-walled), vertical alignment, and work function. Single-walled CNTs (SWCNTs) often demonstrate superior FE properties due to their higher aspect ratio and smaller diameter. Vertical alignment enhances electron emission by maximizing the aspect ratio and reducing the screening effect. Lower-work-function materials result in better performance, while impurities like amorphous carbon degrade emission properties by increasing defects and work function. Additionally, the cathode–anode distance and gaseous environment significantly impact FE properties, with certain gases either enhancing or degrading performance. Optimizing patterned growth techniques to reduce the screening effect ensures effective emission from each CNT. Despite ongoing challenges, the advancements in CNT-based FE indicate a promising future for this technology.

The work reports on the degradation of isoniazid drug by using polyvinyl alcohol (PVA)/polyethylene glycol (PEG) with MWCNTs and V 2 C (MXene) as the nanocomposite materials. Using different ratios of vanadium carbide, the nano composites (MWCNTs@V 2 C) were created by sonication. 0.4 g of PEG and 1.6 g of PVA were sonicated in 20 mL of DMF together with 0.01 g of vanadium carbide or 0.5% of the total weight of the two polymers, PVA and PEG. The same weight % was used to prepare each of the four samples. When MWCNT was absent from the first sample, the weight percentage of MWCNT was altered by 0.1% of PVA/PEG/V 2 C@MWCNT in the second sample (i.e., 0.0020 g), 0. 15% of PVA/PEG/V 2 C@MWCNT in the third sample (i.e., 0.0030 g), and 0.20% of PVA/PEG/V 2 C@MWCNT in the fourth sample (i.e., 0.0040 g), respectively. The use of pure polymers and the nanocomposite V 2 C/MWCNT( x ) ( x = 2, 3, and 4 mg) as microwave‐active catalysts promoted the breakdown of isoniazid drug. In comparison to the other three samples, the fourth sample at 150 mg showed the greatest degradation of 93%, concentration of (60 ppm) ISN. PVA/PEG/V 2 C@MWCNT of 0.004 g showed maximum degradation of 93% when vanadium carbide and different MWCNT concentrations were used as catalyst.

We have studied the response behaviour of bare and embellished Multiwalled Carbon Nanotubes (MWCNTs) in gas sensing, as well as their gas sensing properties have been thoroughly analysed. Pure tantalum oxide (Ta2O5) metal nanoparticles are deposited onto carbon nanotubes using the RF-sputtering technique. In terms of sensing response, the response in a decorated sensor was 565

In this study, diverse thicknesses of zinc oxide (ZnO)-decorated multi-walled carbon nanotubes (MWCNTs) were prepared. The surface of MWCNTs was coated with ZnO nanoparticles during deposition times of 0, 2, 4, and 6 min at 100 Watts (W) power by using the RF-Sputtering technique, with the aim of enhancing both field emission and gas-sensing properties. Comprehensive characterization techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy, were employed to MWCNT growth and the attachment of ZnO nanoparticles to MWCNTs. Field emission studies of ZnO(x)/MWCNTs (where x = 0, 2, 4, and 6 min) indicated a significant increase in current density. Notably, the ZnO(4)/MWCNTs field emitter exhibited superior performance, featuring a lower turn-on voltage (0.83 V/µm), a higher current density (80.03 mA/cm2), and a larger field enhancement factor (27,101). Moreover, this field emitter demonstrated exceptional stability over a 30-h period, outperforming its counterparts, ZnO (0, 2, and 6)/MWCNTs.In addition to the field emission properties, the gas-sensing capabilities of the as-prepared ZnO(x)/MWCNTs were evaluated, particularly focusing on sensitivity towards NH3 gas. The ZnO(4)/MWCNTs sample exhibited remarkable resistance variation, resulting in an outstanding sensor response (1.9 s), rapid response time (4 s), swift recovery time (5 s), and excellent repeatability when compared to other samples. Overall, this study not only elucidates the synthesis and characterization of ZnO-decorated MWCNTs but also highlights the superior field emission and gas-sensing performances of the ZnO(4)/MWCNTs composite, establishing it as a promising candidate for various applications.

In this work, we compared the gas sensing behaviors of pristine and decorated multi-walled carbon nanotubes (MWCNTs) and examined the response behavior of bare and adorned MWCNTs in gas sensing. According to the data, the decorated response was 144%, which is higher than the bare CNT response of 117% in terms of the sensing response. The RF-sputtering method is used to decorate the carbon nanotubes by pure Indium (In) metal nanoparticles. Every measurement was performed in a temperature-controlled environment. Tests of the entire procedure were conducted at a 10 ppm concentration of ammonia gas. We have observed the quick reaction time (1-10 s) in pristine and (1-7 s) in decorated MWCNTs. The response was obtained 117% for the pristine and 144, 115, and 73% for the second (3 min decoration), third (6 min decoration), and fourth (9 min decoration) MWCNTs, respectively. The as-prepared pristine samples and all the decorated sensors had sensitivity values of 0.45, 0.50, 0.51, and 0.57 for time intervals of 0, 3, 6, and 9 min, respectively. It amounted to 45% for the pure and 50, 51, and 57% for the remaining as-prepared decorated sensors, respectively. Based on the measured sensor response graph, a recovery of between 80 and 85% was achieved. For a period of 10 days at a constant concentration, the stability was also assessed and we have analyzed the structural, electrical, and elemental composition of the prepared CNTs by FESEM, EDX, Raman spectroscopy, FTIR, and XRD.

Carbon nanotubes have a large surface area and are porous in nature so they can be highly useful in gas sensing and field emission applications. CNT have advanced electrical properties due to π-π conjugated configuration. In this present work, we have prepared the Fe catalyst and Fe/Cu catalyst via a chemical route. CNTs were synthesized on Fe and Fe/Cu coated silicon substrates using the low-pressure CVD at different gas flow ratios. The growth of CNTs was performed at 700 ℃ temperature by feeding the acetylene gas along with hydrogen as a carrier gas. The growth of CNTs completed in 25 min. Ammonia is a poisonous gas that is renowned as a silent killer. Long-term ammonia gas exposure damages the sensory tissue and promotes headaches. In this work, we study the gas sensing and field emission properties of the as-prepared CNTs in the presence of ammonia gas. The as-prepared samples were characterized by several techniques like scanning electron microscope (SEM) for morphology analysis, Raman spectroscopy to analyse signature peaks and quality of the as-prepared samples. The role of ammonia gas in gas sensing and the change in electronic characteristics in the presence of ammonia gas are being investigated.

This study evaluates the dynamic performance of carbon nanotube field-effect transistors (CNTFETs) incorporating zinc oxide (ZnO) as the gate dielectric material. Multi-walled carbon nanotubes (MWCNTs) were synthesized via low-pressure chemical vapor deposition (LPCVD) to form the channel, while ZnO thin films were deposited using RF sputtering at varying thicknesses (10 nm, 20 nm, 30 nm, and 40 nm). Gold (Au) was utilized for source, drain, and gate contacts due to its superior conductivity and compatibility with carbon nanotubes. Structural characterization using SEM revealed well-aligned CNT channels and robust CNT-metal contacts, ensuring minimal resistance. Electrical characterization highlighted the impact of ZnO thickness on device parameters, with the CNTFET exhibiting a threshold voltage (VTH) of 1 V for a 10 nm ZnO dielectric. The study underscores ZnO's potential as a gate dielectric material, offering a high dielectric constant and compatibility with CNTs, which enhances electrostatic control and reduces short-channel effects. Variations in ZnO thickness significantly influenced key device metrics such as current-voltage characteristics, transconductance, and power dissipation. Thinner ZnO layers (10 nm) demonstrated superior switching performance and energy efficiency, while thicker layers exhibited reduced leakage currents. These findings demonstrate that tuning ZnO gate dielectric properties can optimize CNTFET performance, paving the way for high-speed, energy-efficient nanoscale devices.

The objective of this work was to improve the capacitive behavior of rGO-CNTs composite electrode. The prepared composite has been examined for electric double layer capacitor (EDLCs) devices. The structural and chemical properties of the composite has been validated by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscope (SEM). We performed the cyclic voltammetry (CV) and measured specific capacitance of 54 Fg−1at 10 ​mV/s for 1 ​M ​H2SO4 and 36.25 ​F ​g−1 for 1 ​M KOH liquid electrolyte. From galvanostatic charge-discharge (GCD) studies, 1 ​M H2SO4 electrolytes we obtained the energy density and power density as 10.67 ​Wh kg−1 and 2400 ​W ​kg−1 respectively at 6 A/g. However, 1 ​M KOH electrolytes has an energy density and power density of 1.7 ​Wh kg−1 and 1600 ​W ​kg−1 at 4 A/g. Therefore, the performance of 1 ​M ​H2SO4 electrolytes shows better results as compared to the 1 ​M KOH. Hence, we conclude that rGO-CNTs electrode is an interesting material for supercapacitor applications.

In this study, we propose a new, simple technique for raising the efficiency of field emission devices based on metal organic framework composites. Multi-walled carbon nanotubes (MWCNTs) and ZnO are used in the fabrication of metal-organic frameworks (MOFs) in this technique. This is explained by the composites unique structural structure, which offers a lot of easily available electro active sites, low surface work function, and improved electronic conductivity. One of the less complicated and more economical synthesis methods is used to synthesize the ZnO@MOF/MWCNTs composite. The material's precise morphological and structural features have all been investigated using Raman, FE-SEM, EDX, FTIR, and UV-Visible investigations. The ZnO@MOF/ MWCNTs field emitter show impressive and stable field emission properties, such as a low turn-on electric field 0.50 V/mu m and a high emission current density 219.15 mA/cm2.Our research revealed an easier way for boosting the electron field emission utilized in different field emission display systems that are based on MOF composites.

For vacuum-based electron field-emission device application, CNTs can be a promising field emitter candidate due to the high aspect ratio, superior electrical and thermal properties, and nanoscale tip geometry. In the present work, we study the growth temperature influence on the emission stability of CNT field emitters. The growth and quality of field emitters were controlled by the growth temperature confirmed by FESEM micrograph and Raman spectra. The present study reveals the decline in the turn-on $$({E}_{\mathrm{to}})$$ field (2.154 → 2.012 V/µm) and threshold $$({E}_{\mathrm{th}})$$ field (2.628 → 2.429 V/µm) on rising the growth temperature and increment in the emission current density $$(J)$$ (245.63 → 410.24 µA/cm2 @ 3.06 V/µm field) as well. Furthermore, as the growth temperature increased, the emission stability improved, which might be attributed to the controlled growth of field emitters and the screening effect diminishing with growth temperature.

In this paper, we are studying the effect of different concentrations of CuO on the activation energy of ZnO/Ag 2 O/CuO ternary metal oxide nanocomposites. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Raman spectroscopy were used to determine the structural and topographical features of the produced samples. XRD data indicates that crystalline size increases while crystalline % decreases as the concentration of CuO increases. A FESEM result shows that particle size increases as the CuO concentration increases in ternary metal oxides. Raman spectroscopy indicates that the peaks that are obtained are ZnO, Ag 2 O and CuO peaks. In a dc conductivity measurement, we have seen that when we increase the concentration of CuO in ternary metal oxide, the activation energy increases. We have found that the less concentrated CuO in ternary metal oxides ZnO/Ag 2 O/CuO which have low activation energies indicates that this may be a very stable catalyst with a high rate of activity.

Low-pressure chemical vapour deposition (LPCVD) has been used to grow multi-walled carbon nanotubes (MWCNTs) on a silicon (Si) substrate. The Si substrate is coated with iron (Fe) nanoparticles at different times of deposition at a power of 100 W (W) by using Radio Frequency (RF) sputtering. In this paper, we have prepared MWCNTs with different thicknesses of Fe nanoparticles. To enhance the field emission properties, we coat the surface of MWCNTs with Zinc oxide (ZnO) nanoparticles for 5 min at 100 W power by using the RF sputtering technique. The growth of MWCNTs and the attaching of ZnO nanoparticles on MWCNTs were substantiated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The field emission studies of ZnOx–Fex@MWCNTs (where x represents 5 min) nanostructures show that the current density increases remarkably. Compared to other field emitters such as MWCNTs and ZnO-attached MWCNTs, the ZnO attached MWCNTs had less iron thickness MWCNTs field emitters are better field emitters with lower turn-on voltage, higher current density, higher field enhancement factor, and better repeatability, and they also show good stability over a period of 15 h.

In this study, we have performed two properties (gas sensing and the field emission) of the MWCNTs simultaneously. We have first deposited the iron (Fe) catalyst on silicon (Si) substrate and have then used the low-pressure chemical vapour deposition (LPCVD) method to prepare the carbon nanotubes. We have decorated the CNTs by the metal (Cu) nanoparticles to enhance their electronic properties and to increase the surface area of the as prepared material. We have performed the gas sensing behaviour of the pristine/bare and decorated MWCNTs and compare the gas response behaviour of bare and decorated MWCNTs, a slightly high sensor response is obtained (Rg − Ra)/Ra × 100) of NH3 gas in decorated 65

In this study, silicon (Si) substrates were coated with nickel (Ni) and nickel–titanium (NiTi) using advanced RF sputtering, and carbon nanotubes (CNTs) were synthesized via low-pressure chemical vapor deposition (LPCVD) with precise acetylene/ammonia/hydrogen (C2H2/NH3/H2) flow ratios (30/40/100). The focus was on the remarkable field emission and gas-sensing properties of the resultant CNTs. Field emission scanning electron microscopy (FESEM) and Raman spectroscopy analyses unveiled surface features and structural qualities. Notably, NiTi@MWCNTs exhibited superior performance compared to Ni@MWCNTs, displaying higher current density 5.72mA2 and lower turn-on voltage 1.02 V/μm, indicating enhanced electron emission capability. This study highlights the effectiveness of NiTi@MWCNTs as field emitters due to their exceptional characteristics, underscoring their potential for various applications.