Amino-functionalized Carbon Nanotubes Research Articles

Catalytic activities of tannase covalently linked to amino-functionalized carbon nanotubes

Immobilized Aspergillus ficuum tannase on amino-functionalized multiwalled carbon nanotubes (A-MWCNT) was assembled through glutaraldehyde-mediated covalent coupling to produce a stable biocatalyst nanocomposite. The effective binding of tannase on the surface of A-MWCNT was evaluated and authenticated by spectroscopic signature signals and morphological differences, before and after enzyme coupling. Both free- and immobilized tannase showed optimal catalytic activities at pH 5.0 and 35 °C, with the immobilized tannase exhibiting enhanced thermostability compared to the soluble enzyme. The immobilized tannase preparation was also found to be reusable up to five cycles, with 66% of initial enzyme activity retained thereafter. The enzyme-carbon nanotube composite preparation allows for bioconversion to be accomplished in a bioreactor with a smaller footprint.

A multifunctional coating toward wearable superhydrophobic fabric sensor with self-healing and flame-retardant properties with high fire alarm response

The design of wearable fabric with ultrasensitive fire alarm response and piezoresistive sensor capabilities is urgently imperative to prevent burn injuries to people in the fire accident. Herein, a novel cotton fabric-based piezoresistive sensor comprising hydrophobic waterborne polyurethane, polyphosphazene (PPZ) microspheres encapsulated 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS), and amino-functionalized carbon nanotubes (A-CNTs) was proposed via a roll coating approach, which achieve self-healing, flame-retardant property, and intelligent fire alarm response. The fabric sensor exhibited prominent flame retardancy because of the synergistic formation of a dense flame-retardant layer on the fabric surface by A-CNTs and PPZ. The char residue of the fabric sensor reached 20.4 wt% at 800 °C, and the limiting oxygen index was as high as 27.4 %. Interestingly, benefiting from the thermoelectric characteristic of A-CNTs, the fabric sensor triggered the fire alarm system within 2 s. More importantly, since the resistance changed with their deformations, the fabric sensor can also monitor a variety of human motions, and its sensitivity (GF) can reach 4.79. Additionally, the resulting fabric sensor exhibited self-healing performance. After physical damage, under near-infrared light irradiation, the healing agent FAS spontaneously migrates towards the surface of the fabric, effectively restoring the superhydrophobic property of the fabric. This work provides new insight into the design and application of multifunctional fabric sensors.

Shape memory polyimide/carbon nanotube composite aerogels with physical and chemical crosslinking architectures for thermal insulating applications

The development of lightweight smart materials with exceptional shape memory and thermal insulation properties is highly important in the aerospace industry. The reported shape memory polymer aerogels (SMPAs) are restricted to harsh environments because of their poor high-temperature resistance and large volume shrinkage at elevated temperatures. Herein, shape memory polyimide (PI) composite aerogels with superior thermal insulation were fabricated by combining molecularly designed PI chains with amino-functionalized carbon nanotubes (NH2-CNTs) through freezing gelation and subsequent thermal imidization. Because shape memory behavior was thermally triggered, the thermal conductivity associated with the shape memory mechanisms of the aerogels was comprehensively explored. The presence of CNTs promoted heat transfer in the aerogel skeleton, facilitating the shape recovery response. Benefiting from chemical-crosslinked and physical-crosslinked structures, the fabricated PI composite aerogels demonstrated desirable thermo-mechanical properties, exceptional shape memory and superior thermal insulation performance. This study may provide guidelines for designing shape memory PI composite aerogels for harsh environment applications in aerospace engineering.

Electrostatically self-assembled three-dimensional conductive network for highly sensitive and reliable skin-like strain sensor

In recent years, flexible strain sensors have garnered significant attention in industrial manufacturing and daily life. Sensitivity and reliability are two crucial characteristics of flexible strain sensors in practical applications, and they depend on the development of the sensor's internal conductive network. However, the aggregation phenomenon of conductive fillers in the elastic matrix has a serious impact on the construction of a developed conductive network. In this work, we have designed electropositive amino-functionalized carbon nanotubes (CNTs-p) based on the electrostatic self-assembly of electronegative MXene in the aqueous phase. Compared to the use of surfactants, the electrical modulation of carbon nanotubes through chemical bonding modification is more robust and the electrostatic self-assembly with MXene is more stable. CNTs-p and MXene were self-assembled by electrostatic attraction in butyl latex and uniformly dispersed in the latex. Following demulsification, the polymer composite film (MXene&CNTs-p/IIR) with a three-dimensional conductive network was obtained. The skin-like strain sensor, which utilizes the conductive composite film, demonstrates high sensitivity (gauge factor (GF) = 35137 that is among the highest values for the reported strain sensor), remarkable reliability (The signal monitoring capability remains after 15000 cycles), and excellent responsiveness (62 ms). Additionally, the skin-like strain sensor boasts a wide detection range (0–431%) and unprecedented stability, enabling strain sensing functionality in a wide temperature range of -10—100 °C, as well as strong acid (pH = 1) and strong alkali (pH = 11) environment. The preparation of MXene&CNTs-p/IIR provides a safe, environmentally friendly and effective method for improving the sensitivity and reliability of flexible sensors in wearable intelligent electronics and health detection.

Effect of NH2-MWCNTs/CF anodes on the power generation performance of SMFCs

The carbon nanotube-modified anodes have been widely recognized as one of the most effective methods to improve the conductivity of the anode and enhance the performance of microbial fuel cells. And there are few studies on the effect of amino-functionalized carbon nanotube-modified anodes on the performance of sediment microbial fuel cells (SMFCs) systematically. In this paper, we prepared amino-functionalized carbon nanotube-modified electrodes and constructed SMFCs using them to study the effect of amino-functionalized carbon nanotubes on the power generation performance of SMFCs. The results showed that the highest output voltage of NH2-functionalized multi-walled carbon nanotube (NH2-MWCNT)-modified carbon felt (CF) SMFCs (529.15 mV) was significantly higher than that of CF (474.5 mV). And the power density of SMFCs with 10% NH2-MWCNTs/CF reached a maximum of 58.3 mW/m3. There are because NH2-MWCNTs surface has a larger specific surface area and a porous structure, enhancing electron conduction pathway helps to improve the conductivity of the anode. Therefore, the modification of CF surfaces with NH2-MWCNTs can be used to improve the interfacial properties and positively enhance the power generation performance of SMFCs. This study provides a novel and effective approach to enhance the performance of SMFCs and contributes to the international research on carbon nanotube-modified anodes for energy and environmental applications.

Thermal properties and mechanical behavior of functionalized carbon nanotube-filled polypropylene composites using molecular dynamics simulation

Polypropylene (PP) is widely recognized as an environmentally friendly material for cable insulation due to its good insulation performance and environmental friendliness. One common method for enhancing the overall performance of PP is the addition of nanoparticles. To analyze the influence of different functionalized multi-walled carbon nanotubes (MWCNT) fillers on the properties of PP/MWCNT composite materials from a microscale perspective, molecular dynamics is used to construct pure PP models and models filled with untreated carbon nanotubes (UFCNT), amino-functionalized carbon nanotubes (AFCNT), carboxyl-functionalized carbon nanotubes (CFCNT), and hydroxyl-functionalized carbon nanotubes (HFCNT) (functionalized MWCNT with 4 or 8 functional groups grafted onto them). The simulation results indicate that the doping of nanotubes can effectively enhance the thermodynamic properties of PP. Among them, PP/CFCNT-8 exhibits the most significant improvement in melting temperature and mechanical properties, with an increase in melting temperature of 88.85 K and a 184.52 % increase in Young's modulus. The melting temperature of PP/HFCNT-8 is second only to PP/CFCNT-8, with an increase of 82.59 K. The results indicate that the thermodynamic properties of PP nanocomposites filled with functionalized MWCNT are improved with the grafting rate. The filling of functionalized MWCNT alters the microscale properties of PP composites, with a significant decrease in root mean square displacement (RMSD), and improvement in free volume fraction (FFV) as well as interfacial binding energy, which can better maintain the electrical properties of PP insulation materials. Applying functionalized carbon nanotubes to filled PP can significantly increase the electrical insulation properties of PP cable materials, which provides meaningful guidance for adopting polypropylene cable insulation materials.

Self-assembled composite Langmuir-Blodgett films of carbon nanotubes: An approach to enhance surface-enhanced Raman scattering and photoelectric performance

Self-assembly is a technique that utilizes non-covalent interactions between molecules to assemble into ordered nano-scale aggregates from disordered states. Langmuir-Blodgett (LB) technique is one of the commonly applied methods for constructing molecular assemblies at gas-liquid interfaces. In this study, a series of ordered composite films of amino-functionalized carbon nanotubes (MWCNTs-NH2) and different dye molecules were prepared using LB technique. The surface-enhanced Raman scattering (SERS) performance of MWCNTs-NH2/dye composite films was investigated. The experimental results showed that MWCNTs-NH2/Methylene blue (MB) composite film exhibited good SERS enhancement performance for Rhodamine 6 G (R6G) molecules with an enhanced factor (EF) of 2.16 × 105, and had certain repeatability and uniformity, making it suitable for the detection of trace molecule. The photoelectric conversion efficiency of MWCNTs-NH2/dye composite films were also explored. MWCNTs-NH2/MB composite film not only exhibited the highest photocurrent value but also had the smallest impedance compared with the other films, indicating that it had lower impedance, better carrier transport rate, and more stable performance. This work provides an effective method for fabricating the composite LB films based on the carbon nanotubes with great SERS and photoelectric conversion efficiency.

Insight into the enhancement effect of amino functionalized carbon nanotubes on the H2S removal performance of nanofluid system

By constructing nanofluid system, trace functionalized nanoparticles can significantly enhance the absorption performance of basic liquid. In this work, amino functionalized carbon nanotubes (ACNTs) and carbon nanotubes (CNTs) were introduced into alkaline deep eutectic solvents to build nanofluid systems and used for the dynamic absorption of H2S. The experiment results showed that the introduction of nanoparticles can significantly enhance the H2S removal performance of original liquid. When performing H2S removal experiments, the optimal mass concentrations of ACNTs versus CNTs were 0.05 % and 0.01 %, respectively. The characterization showed that the surface morphology and structure of the nanoparticles unchanged significantly during the absorption-regeneration process. A double mixed gradientless gas-liquid reactor was used to explore the gas-liquid absorption kinetics characteristics of the nanofluid system. It was found that the gas-liquid mass transfer rate increased significantly after the addition of nanoparticles. The highest total mass transfer coefficient of the nanofluid system of ACNTs was increased to more than 400 % of the value before the addition of nanoparticles. The analysis showed that the shuttle effect and hydrodynamic effect of nanoparticles play important role in the process of enhancing gas-liquid absorption, and the amino functionalization enhanced the shuttle effect of nanoparticles significantly.

Amino-functionalized carbon nanotubes stimulating γ-MnO2 to achieve high-performance zinc-ion batteries

With suitable operating voltage and high capacity, manganese dioxide (MnO2) shows great potential for the cathode of aqueous zinc ion batteries. However, its cycling stability is severely limited by the unstable host structure and inevitable dissolution of Mn2+. Herein, the amino-functionalized carbon nanotubes (MWCNTs-NH2) are introduced to construct the MWCNTs-NH2/γ-MnO2 nanocomposite (NCM) to significantly stimulate the cyclic stability of γ-MnO2. On the one hand, MWCNTs-NH2 can give impetus for stable integral structure and good overall electrical conductivity to γ-MnO2 through homogeneous three-dimensional mechanical and conductive networks. On the other hand, the amino groups of MWCNTs-NH2 can participate in the storage of Zn2+/H+ and, most importantly, boost the deposition of Mn2+ ions from the electrolyte to the cathode to inhibit the loss of active substance in the long-term cycle. Driven by these advantageous effects, the NCM cathode exhibits an ultra-high capacity of 417.9 mAh g−1 at 0.2 A g−1 and a long cycling life over 3500 cycles at 3.0 A g−1 with 91.4% capacity retention. This study reveals the importance of promoting Mn2+ deposition in Zn-MnO2 batteries and presents an effective strategy for achieving stable cycling of MnO2 cathodes.

A highly flame-retardant, agile fire-alarming and ultrasensitive cotton fabric-based piezoresistive sensor for intelligent fire system

With the high frequency of fires, multifunctional cotton fabrics with high flame retardancy and agile fire-warning ability are urgently needed. Herein, a newly cotton fabric-based piezoresistive sensor (denoted as CF@A-CNTs/APP) with intelligent fire protection and high sensitivity is proposed, which is composed of amino-functionalized carbon nanotubes (A-CNTs) and ammonium polyphosphate (APP) wrapped on cotton fabric (CF) using layer-by-layer self-assembly. The CF@A-CNTs/APP demonstrated excellent flame retardancy due to the synergistic formation of a dense flame retardant layer on the CF surface by A-CNTs and APP. The char residue of CF@A-CNTs/APP reached 44.0 wt% at 700 °C (nitrogen atmosphere), and the limiting oxygen index of CF@A-CNTs/APP was as high as 37.6%. More importantly, the CF@A-CNTs/APP triggered the fire-alarming system within 2 s. Benefiting from the pattern microstructures of double-layers CF and the high conductivity of A-CNTs, the CF@A-CNTs/APP has exhibited a high sensitivity of 3.8 kPa−1 (0 kPa-16.62 kPa). In view of outstanding flame retardancy, high sensitivity and robustness, the CF@A-CNTs/APPs could be integrated into firefighting suits or electronic skins to monitor the behavioral actions and equipment operating conditions. This work provides a novel strategy for a new generation of CF-based sensors with fire resistance and high sensitivity, and offers new insights into the preparation and application of smart fire-resistant materials in the field of the internet of things.

Temperature-triggered fire warning PEG@wood powder/carbon nanotube/calcium alginate composite aerogel and the application for firefighting clothing

The design and exploitation of highly fire-safe aerogel with ultrasensitive fire-warning response and highly efficient thermal management capabilities are urgently needed to protect firefighters from burn injuries during fire operations and rescue. Herein, an ultralight temperature-triggered fire-warning aerogel composited of polyethylene glycol (PEG)@modified wood powder (MW)/amino-functionalized carbon nanotube (A-CNT)/calcium alginate (CA) (abbreviated as P@MW-A-CA) was fabricated. Benefiting the rapid decrease in electrical resistance of A-CNT at high temperatures, P@MW-A-CA achieved an ultrafast fire warning response time of ∼2.03 s when exposed to fire. Meanwhile, PEG was encapsulated into MW and acted as microtubule phase-change material (P@MW) in aerogel to effectively delay the heat penetration into P@MW-A-CA. The stiff MW served as the backbone endowed the fire-warning aerogel a “stiff-soft” structure that increased the mechanical resilience. P@MW-A-CA achieve flyweight density (0.038 g/cm3), low thermal conductivity (0.06233 ± 0.0012 W/m⋅K), and outstanding self-extinguishment (<1.02 s). This work provides an environmental friendliness approach to design an ultralight early fire-warning aerogel in firefighting clothing for enhancing the fire safety of firefighters.

Effect of pH-Dependent Homo/Heteronuclear CAHB on Adsorption and Desorption Behaviors of Ionizable Organic Compounds on Carbonaceous Materials.

Herein, the adsorption/desorption behaviors of benzoic acid (BA) and phthalic acid (PA) on three functionalized carbon nanotubes (CNTs) at various pH were investigated, and the charge-assisted H-bond (CAHB) was verified by DFT and FTIR analyses to play a key role. The results indicated that the adsorption order of BA and PA on CNTs was different from Kow of that at pH 2.0, 4.0, and 7.0 caused by the CAHB interaction. The strength of homonuclear CAHB (≥78.96 kJ·mol−1) formed by BA/PA on oxidized CNTs is stronger than that of heteronuclear CAHB formed between BA/PA and amino-functionalized CNTs (≤51.66 kJ·mol−1). Compared with the heteronuclear CAHB (Hysteresis index, HI ≥ 1.47), the stronger homonuclear CAHB leads to clearly desorption hysteresis (HI ≥ 3.51). Additionally, the contribution of homonuclear CAHB (≥52.70%) was also greater than that of heteronuclear CAHB (≤45.79%) at pH 7.0. These conclusions were further confirmed by FTIR and DFT calculation, and the crucial evidence of CAHB formation in FTIR was found. The highlight of this work is the identification of the importance and difference of pH-dependent homonuclear/heteronuclear CAHB on the adsorption and desorption behaviors of ionizable organic compounds on carbonaceous materials, which can provide a deeper understanding for the removal of ionizable organic compounds by designed carbonaceous materials.

Modulating the adsorption orientation of methionine-rich laccase by tailoring the surface chemistry of single-walled carbon nanotubes

Achieving fast electron transfer process between oxidoreductase and electrodes is pivotal for the biocathode of enzymatic biofuel cells (EBFCs). However, in-depth understanding of the interplay mechanism between enzymes and electrode materials remains challenging when designing and constructing EBFCs. Herein, atomic-scale insight into the direct electron transfer (DET) behavior of Thermus thermophilus laccase (TtLac) with a special methionine-rich β-hairpin motif adsorbed on the carboxyl-functionalized carbon nanotube (COOH-CNT) and amino-functionalized carbon nanotube (NH2-CNT) surfaces were disclosed by multi-scale molecular simulations. Simulation results reveal that electrostatic modification is an effective way to tune the DET behavior for TtLac on the modified-CNTs electrode surface. Surprisingly, the positively charged TtLac can be attracted by both negatively charged COOH-CNT and positively charged NH2-CNT surfaces, yet only the latter is capable to trigger the DET process due to the ‘lying-on’ adsorption orientation. Specifically, the T1 copper site is near the methionine-rich β-hairpin motif, which is the key binding site for TtLac binding onto the NH2-CNT surface via electrostatic interaction, π−π stacking and cation−π interaction. Moreover, TtLac on the NH2-CNT surface undergoes less conformational changes than those on the COOH-CNT surface, which allows the laccase stability and catalytic efficiency to be well preserved. These findings provide a fundamental guidance for future design and fabrication of methionine-rich laccase-based EBFCs with high power output and long lifespan.

Molecular modulating of cobalt phthalocyanines on amino-functionalized carbon nanotubes for enhanced electrocatalytic CO2 conversion

Molecular modulating of cobalt phthalocyanines on amino-functionalized carbon nanotubes for enhanced electrocatalytic CO2 conversion

Improving surface properties of cathode and increasing abundance of autotrophic bacteria for chromium reduction with amino functionalized carbon nanotubes

Chromium reduction by electrochemically active bacteria on the biocathode of bioelectrochemical systems is a promising bioremediation technology. However, the poor conductivity and surface properties of conventional carbon cathode materials greatly limit the adhesion and enrichment of Cr-reducing bacteria on the electrode surface. In our study, a conductive cathode with aminated surface was assembled layer-by-layer with polystyrene sulfonic acid and amino carbon nanotubes (NH2-CNT). The electrode displayed high chromate ions adsorption capacity, and the sediment microbial fuel cell (SMFC) with it as the cathode output the highest voltage of 241 mV and was able to remove 98 % of the Cr (VI) in the upper water. The attached NH2-CNT layer promoted the formation of biofilm on the cathode, as well as the secretion of extracellular protein. In addition, the relative abundances of Cr-reducing bacteria, such as Rhodobacter, Hyphomicrobium, Leucobacter, Sphaerotilus and Acetobacterium, were greatly enriched. This significantly increased the chromium reducing rate of the SMFC with NH2-CNT electrode by 2.06 times, compared with the control. These results suggested that the NH2-CNT modified cathode could improve the interfacial properties of SMFCs and promote the enrichment of Cr-reducing bacteria. This work provides a new strategy to increase the bioremediation efficiency of heavy metals.

Tailoring the permeability and flux stability of forward osmosis membrane with tert-butylamine functionalized carbon nanotubes for paracetamol removal

The discharge of pharmaceutical wastewater is an adversity to the nature. Some of the pharmaceutical product (PP) wastes are highly resistant towards bio-degradation hence physical-based separation technology such as forward osmosis (FO) has been introduced for the treatment. Despite exhibiting high water flux, commercial FO membrane often suffers from fouling and unsatisfactory solute rejection. In this study, carbon nanotubes (CNT) which has high self-bundling tendency was functionalized with tert-butylamine (TBA), a bulky tertiary amine. The agglomeration of the aminated CNT was suppressed via steric hindrance and surface charge repulsion. The nanofillers was then incorporated into the polyamide (PA) layer of thin film nanocomposite (TFN) during interfacial polymerization process to provide the required hydrophilicity and surface charges. Using synthetic paracetamol (PCT) solution as the feed solution (FS), the experimental outcome showed that the incorporation of amino-functionalized CNT (ACNT) successfully enhanced the hydrophilicity and flux stability of the FO membranes. Compared to the control thin film composite (TFC) membrane, ACNT-TFN membrane exhibited an improved water flux from 3.58 L.m−2.h−1 to 9.01 L.m−2.h−1, without sacrificing the PCT rejection (99.7 %). This study improves the understanding on the superior benefits of FO for enhancing the pharmaceutical waste removal and stimulates insight for more nanofillers-induced modification on the FO membrane, in order to make it truly useful for more water separation applications in the future.

Detection of Nitroaromatic Explosives in Air by Amino-Functionalized Carbon Nanotubes

Nitroaromatic explosives are the most common explosives, and their detection is important to public security, human health, and environmental protection. In particular, the detection of solid explosives through directly revealing the presence of their vapors in air would be desirable for compact and portable devices. In this study, amino-functionalized carbon nanotubes were used to produce resistive sensors to detect nitroaromatic explosives by interaction with their vapors. Devices formed by carbon nanotube networks working at room temperature revealed trinitrotoluene, one of the most common nitroaromatic explosives, and di-nitrotoluene-saturated vapors, with reaction and recovery times of a few and tens of seconds, respectively. This type of resistive device is particularly simple and may be easily combined with low-power electronics for preparing portable devices.

Multi-functional air filters with excellent flame retardancy and fire-warning capability

High fire-safe air filters are indispensable for indoor environments, such as vehicle interior, fresh air filtration system, and window screens. However, it is still challenging to afford both excellent flame retardancy and rapid fire-warning capability in air filters. In this study, we fabricate a type of high-efficient fiber filters with combined flame-retardant and fire-warning performance. Nanofibers with a specific tri-layer structure are designed to incorporate Polyacrylonitrile (PAN) matrix and two functional components, flame retardant ammonium polyphosphate (APP) and amino-functionalized carbon nanotube (A-CNTs). The resultant PAN/CNTs/APP fiber filters have high PM2.5-10 capture efficiency of > 99.99%. The filters can not be burnt in vertical burning test and exhibit high limiting oxygen index value of 30.9%. Moreover, the resultant PAN/CNTs/APP fiber filters achieve short fire-warning response time (∼5s) when encounters fire. This work offers a facile and cost-effective approach to fabricate multifunctional air filters, and shows promising applications in vehicle interior, firefighting, fresh air filtration and building materials.

Amino-functionalized carbon nanotubes/polyphosphazene hybrids for improving the fire safety and mechanical properties of epoxy

To expand further modern industrial applications of epoxy resin (EP), the urgent problems of flammability and poor mechanical properties have to be solved. Therefore, amino-functionalized carbon nanotubes (AFP@CNTs) was designed and successfully synthesized to enhance the comprehensive properties, including fire safety and mechanical properties. Especially, the flame retardant mechanism, the combustion and pyrolysis process of EP/AFP@CNTs were investigated as well. With the addition of 1.5 ​wt% AFP@CNTs, the peak heat release rate (PHRR) and total heat release (THR) of EP were reduced by 27.6% and 29.0%, respectively, which may due to the cooperative effect between the phosphorus-nitrogen synergistic flame retardant of polyphosphazene and the cohesive phase flame retardant of carbon nanotubes. In addition, the mechanical performance of EP/AFP@CNTs composites were also investigated. The results showed that the impact strength, tensile strength and the storage modulus effectively increased by 65.0%, 29.0% and 13.2%, respectively. Meanwhile, the change of the combustion and pyrolysis process of EP/AFP@CNTs may be attributed to the catalytic effect of the amino-functionalized polyphosphazene, which could participate in the formation of epoxy thermal curing crosslinking network and catalyze the degradation process of epoxy resin.

The enhanced activity of dinuclear metallophthalocyanines amino-functionalized carbon nanotube-based oxygen reduction reaction catalysts

Dinuclear metallophthalocyanines Fe2Pc2(CP)4 containing carboxyl substitutes were wrapped with amino-functionalized carbon nanotubes (MWCNTs-NH2) to enhance electrocatalytic activity for oxygen reduction reaction (ORR) using a facile “in situ” amidation reaction. The morphological characteristics and chemical environment of the Fe2Pc2(CP)4/MWCNTs-NH2 composites were characterized by scanning electron microscope (SEM), X-ray diffraction, Ultraviolet–visible (UV-Vis), Fourier Transform infrared (FTIR), and X-ray photoelectron spectroscopy. The electrocatalytic activity of ORR was tested and analyzed by cyclic voltammetry and linear sweep voltammetry. The results showed that the π–π interactions between the Fe2Pc2(CP)4 and MWCNTs-NH2 dramatically enhanced the π electron density in the conjugated structure, and oxygen could be reduced much more easily. Moreover, the oxygen reduction reactions mainly proceeded a one-step four electron process for Fe2Pc2(CP)4/MWCNTs-NH2 catalysts. The dispersion and electrocatalytic performance of M2Pc2Rn had be enhanced after being loaded on functionalized carbon nanotubes.