Nitrogen-doped Carbon Nanotubes Research Articles

Ni-Cu bimetallic alloy anchored on nitrogen-doped carbon nanotubes for CO2-to-CH4 electrochemical conversion

Ni-Cu bimetallic alloy anchored on nitrogen-doped carbon nanotubes for CO2-to-CH4 electrochemical conversion

Highly Dispersed Mn-Doped Ceria Supported on N-Doped Carbon Nanotubes for Enhanced Oxygen Reduction Reaction.

The weak adsorption of oxygen on transition metal oxide catalysts limits the improvement of their electrocatalytic oxygen reduction reaction (ORR) performance. Herein, a dopamine-assisted method is developed to prepare Mn-doped ceria supported on nitrogen-doped carbon nanotubes (Mn-Ce-NCNTs). The morphology, dispersion of Mn-doped ceria, composition, and oxygen vacancies of the as-prepared catalysts were analyzed using various technologies. The results show that Mn-doped ceria was formed and highly dispersed on NCNTs, on which oxygen vacancies are abundant. The as-prepared Mn-Ce-NCNTs exhibit a high ORR performance, on which the average electron transfer number is 3.86 and the current density is 24.4% higher than that of commercial 20 wt % Pt/C. The peak power density of Mn-Ce-NCNTs is 68.1 mW cm-2 at the current density of 138.9 mA cm-2 for a Zn-air battery, which is close to that of 20 wt % Pt/C (69.4 mW cm-2 at 106.1 mA cm-2). Density functional theory (DFT) calculations show that the oxygen vacancy formation energies of Mn-doped CeO2(111) and pure CeO2(111) are -0.55 and 2.14 eV, respectively. Meanwhile, compared with undoped CeO2(111) (-0.02 eV), Mn-doped CeO2(111) easily adsorbs oxygen with the oxygen adsorption energy of only -0.68 eV. This work provides insights into the synergetic effect of Mn-doped ceria for facilitating oxygen adsorption and enhancing ORR performance.

Metal-support interface engineering for stable and enhanced hydrogen evolution reaction

Hydrogen has emerged as a green and sustainable pathway towards achieving global decarbonization and net-zero emissions, intensely driving the need for efficient hydrogen production protocols. Electrocatalytic hydrogen evolution reaction (HER) holds great potential as a scalable, eco-friendly and safe avenue for efficient hydrogen production. However, the large-scale implementation of electrocatalytic HER is substantially challenged by the high-cost and unstable materials that are mainly fabricated from noble metals, e.g., Pt and Pd. Given this challenge, we adopted an interface engineering strategy to immobilize nanoscale Pt particles within the framework of nitrogen-doped CNTs, namely Pt@N-CNTs, where electronic metal-support interaction (EMSI) plays an important role in enabling orbital rehybridization and regulating the charge transfer through the metal-support interface, thereby considerably improving the electrocatalytic activity. With limited content of noble metals, our developed Pt@N-CNTs delivered superior HER performance with an ultralow overpotential of 5.8 mV at 10 mA cm−2 and demonstrated a high mass activity of 12.72 A mgPt−1 at an overpotential of 50 mV as well as excellent stability under harsh acidic conditions. At 500 mA cm−2, Pt@N-CNTs surprisingly exhibited an overpotential of 55.2 mV, outperforming that of commercial 20 wt% Pt/C catalysts (131.5 mV). Importantly, we established a straightforward, scalable, and time-saving microwave reduction strategy, alluding to its promising commercial viability. This work therefore sheds light on the development of high-performance electrocatalysts for hydrogen evolution and water electrolysis.

Efficient activation of peracetic acid by cobalt modified nitrogen-doped carbon nanotubes for drugs degradation: Performance and mechanism insight

Peracetic acid (PAA) has garnered significant attention as a novel disinfectant owing to its remarkable oxidative capacity and minimal potential to generate byproducts. In this study, we prepared a novel catalyst, denoted as cobalt modified nitrogen-doped carbon nanotubes (Co@N-CNTs), and evaluated it for PAA activation. Modification with cobalt nanoparticles (∼4.8 nm) changed the morphology and structure of the carbon nanotubes, and greatly improved their ability to activate PAA. Co@N-CNTs/PAA catalytic system shows outstanding catalytic degradation ability of antiviral drugs. Under neutral conditions, with a dosage of 0.05 g/L Co@N-CNT-9.8 and 0.25 mM PAA, the removal efficiency of acyclovir (ACV) reached 98.3% within a mere 10 min. The primary reactive species responsible for effective pollutant degradation were identified as acetylperoxyl radicals (CH3C(O)OO•) and acetyloxyl radicals (CH3C(O)O•). In addition, density functional theory (DFT) proved that Co nanoparticles, as the main catalytic sites, were more likely to adsorb PAA and transfer more electrons than N-doped graphene. This study explored the feasibility of PAA degradation of antiviral drugs in sewage, and provided new insights for the application of heterogeneous catalytic PAA in environmental remediation.

Tailoring the high-density active sites via metal-coordinated ionic liquid encapsulated trimetallic core-shell MOF-derived catalysts for superior ORR in flexible Al-air batteries

The attainment of practicality in flexible Al-air batteries is impeded by the need for efficient air cathodes. To address this challenge, we systematically engineered the trimetallic (ZnCoFe)NC catalyst with a unique morphology of nitrogen-doped carbon nanotubes (NCNTs) on the 3D polyhedral structure (IL-ZnCoFe@CNT/NC) as an effective cathode. The augmented growth of NCNT facilitated by the metal-coordinated ionic liquid enhances both the specific surface area and the electrochemically active surface area (ECSA). As a result, IL-ZnCoFe@CNT/NC material exhibits a higher onset (1.0 V vs RHE) and half-wave potential (E1/2 = 0.89 V vs. RHE) as well as low Tafel slope (61 mV/dec) and surpassed the bare MOF-derived catalysts and Pt/C. E1/2 decreased by only 7 mV after the stability test describes the durability and fast reaction kinetics in the ORR. Upon testing on flexible Al-air with IL-ZnCoFe@CNT/NC cathode catalysts, it exhibited an OCV of 1.49 V and a peak power density of 34.7 mW cm−2 with 1.3 times higher power performance than the commercial Pt/C along with 3 times longevity than bare catalysts. Additionally, the Density-functional theory (DFT) calculations provide rational evidence that the IL-ZnCoFe@CNT/NC catalyst has an upshifted d-band center, which, in turn, enhances the adsorption of reaction intermediates, making the catalyst highly promising towards ORR.

N-doped clay-like Ti3C2Tx MXene/N-doped CNTs composites for ethylene glycol detection in ambient air and exhaled breath

Ethylene glycol is odorless and harmful to humans. Each year, a large number of fatal cases are caused by ethylene glycol poisoning. Therefore, rapid identification of ethylene glycol is crucial. In this study, clay-like Ti3C2Tx MXene exhibits a larger interlayer spacing compared to accordion-like Ti3C2Tx MXene, which enhances the gas diffusion channels. Nitrogen doping can increase the active sites of clay-like Ti3C2Tx MXene. The introduction of nitrogen-doped carbon nanotubes into N-Ti3C2Tx was carried out to enhance selectivity towards ethylene glycol, leading to the formation of N-Ti3C2Tx MXene/N-CNTs. The N-Ti3C2Tx MXene/N-CNTs exhibits significant selectivity towards the ethylene glycol at room temperature. Meanwhile, the detection limit was 0.3484 ppm, with a shortened response/recovery time of 10.57/6.29 s. Meanwhile, the ethylene glycol sensor device has been prepared through custom-made circuit boards and sensing programs. Moreover, the adsorption and oxidation process of ethylene glycol on N-Ti3C2Tx MXene/N-CNTs was explored through in-situ infrared spectroscopy testing. This study revealed that the oxygen vacancies on the surface of N-Ti3C2Tx MXene/N-CNTs play a crucial role in the oxidative catalytic detection of ethylene glycol. The strategy of N-Ti3C2Tx MXene/N-CNTs provides a new avenue for the detection of ethylene glycol.

Activation of peroxymonosulfate and peroxydisulfate by nitrogen-doped carbon nanotubes for effective degradation of neonicotinoid insecticides

Nitrogen-doped carbon nanotubes (N-CNTs) have been considered as an excellent metal-free activator for persulfate-based advanced oxidation processes. However, the critical role of N-doping in the activation of peroxymonosulfate (PMS) and peroxydisulfate (PDS) remains a significant difference even opposed in scientific understanding. Herein, the CNTs and N-CNTs were used to active PMS and PDS for degradation of neonicotinoid insecticides (NNIs), one of the emerging refractory organic pollutants. The N-CNTs achieve 92.6% of nitenpyram (Nit) degradation within only 10min under PMS system, much higher than that of CNTs/PMS system (~10%). Moreover, the N-CNTs can active PMS to conduct degradation through a combined 1O2 and electron transfer process with k of 4.94 × 10-2L·mg-1·min-1, which was quite different from N-CNTs/PDS system (single electron transfer process, k = 1.84 × 10-3 L·mg-1·min-1). A positive correlation between degradation rates of five NNIs and their electron-donating ability is established, further verifying the importance of electron transfer in NNIs degradation. This study proves the superiority of N-CNTs/PMS over N-CNTs/PDS in Nit degradation and the underlying mechanisms, and reveals the importance of electron-donating ability of NNIs in their degradation by N-CNTs/PMS. These findings are of great significance for their removal from the environment.

Enhanced activity and durability of Pt nanoclusters catalyst by using nitrogen-doped carbon layer coated carbon nanotubes as anchors and nanowires for ORR

Platinum-based catalysts remain the top choice for oxygen reduction reaction (ORR) in fuel cells. However, their activity and durability in the acidic medium are still under improvement. In this work, the Pt nanoclusters anchored the nitrogen-doped carbon nanotubes (Pt-NCNTs) have been synthesized by using a series process of pyrrole coating on the CNTs and subsequent pyrolysis to the chemical immersion reduction of Pt ions. The inner CNTs of Pt-NCNTs function as the nanowires offering a high-speed pathway for electron transport, and the Pt nanoclusters increases the active sites. The theoretical calculation demonstrates that the local structural defects and the uneven charge distribution induced by nitrogen-containing functional groups and porous structure are favorable to capture Pt ions for the nucleation of Pt nanoclusters. Compared with the commercial 40wt% Pt/C (0.94 and 0.80V), the Pt-NCNTs-1000 with Pt loading amount of 33.0wt% owns the more positive onset potential and half-wave potential of 0.97 and 0.81V in the sulfuric acid medium. Meanwhile, the strong attachment of Pt nanoclusters on the nitrogen-doped porous carbon layer results in a stable interface to effectively prevent the metallic species from migration and agglomeration during the electrode reactions. Therefore, the ORR current of Pt-NCNTs-1000 retained 84.3% of the initial value after 50000s operation superior to the commercial Pt/C (64.6%).

Metal–organic framework–derived trimetallic particles encapsulated by ultrathin nitrogen-doped carbon nanosheets on a network of nitrogen-doped carbon nanotubes as bifunctional catalysts for rechargeable zinc–air batteries

Economical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional catalysts with high activity aimed at replacing precious metal catalysts for rechargeable zinc-air batteries (ZABs) must be developed. In this study, a multiple hierarchical-structural material is developed using a facile dielectric barrier discharge (DBD) plasma surface treatment, solvothermal reaction, and high-temperature carbonization strategy. This strategy allows for the construction of nanosheets using nitrogen-doped carbon (NC) material-encapsulated ternary CoNiFe alloy nanoparticles (NPs) on a network of NC nanotubes (NCNTs), denoted as CoNiFe–NC@p–NCNTs. Precisely, the presence of abundant CoNiFe alloy NPs and the formation of M–N–C active sites created by transition metals (cobalt, nickel, and iron) coupled with NC can provide superior OER/ORR bifunctional properties. Moreover, the prepared NC layers with a multilevel pore structure contribute to a larger specific surface area, exposing numerous active sites and enhancing the uniformity of electron and mass movement. The CoNiFe0.08–NC@p–NCNTs show remarkable dual functionality for electrochemical oxygen reactions (ORR half-wave potential of 0.811 V, limiting current density of 5.73 mA cm−2 measured with a rotating disk electrode at a rotation speed of 1600 rpm, and OER overpotential of 351 mV at 10 mA cm−2), which demonstrates similar ORR performance to 20 wt% Pt/C and better OER performance than the commercial RuO2. A liquid ZAB prepared using the proposed material has excellent bifunctionality with an open-circuit voltage of 1.450 V and long-term cycling stability of 230 h@10 mA cm−2.

Multifunctional carbon aerogels loaded with pea-pod-like carbon nanotubes for outstanding electromagnetic wave absorption performance

Although ordered porous carbon materials (PCMs) have shown promising potential in the field of electromagnetic wave absorption (EWA), creating multifunctional PCMs with outstanding microwave absorption performance remains a significant challenge. Herein, ordered porous carbon aerogels loaded with pea-pod-like nitrogen-doped carbon nanotubes (CNTs) were fabricated via orientation freeze-drying followed by high-temperature pyrolysis. The optimized aerogel exhibits extraordinary EWA performance with a broad effective absorption bandwidth of 7.68 GHz and exceptionally strong absorption of −91.58 dB at a low filling ratio of only 3 wt%, which is the largest absorption strength among all known aerogels to date. The exceptional EWA performance is attributed to the synergistic effect of abundant loss mechanisms resulting from a unique pod-like structure in ordered porous carbon aerogel, where nitrogen-doped CNTs encapsulate magnetic alloy nanoparticles. Optimized aerogel exhibits superior compressive elasticity, thermal insulation, and light weight, laying the groundwork for designing practical next-generation EWA materials.

Enhancing the performance of catalytic membranes for simultaneous degradation of dissolved organic phosphonates and phosphorous recovery: A fit-for-purpose loose nanofiltration design

In this study, we developed a loose nanofiltration catalytic membrane (LNCM) by incorporating nitrogen-doped carbon nanotubes (NCNT) into graphene oxide (GO) membrane (NCNT@GO-M) to activate peroxymonosulfate for efficient phosphonates degradation into phosphate, reducing phosphorus-based pollution and facilitating P recovery. The NCNT@GO-M exhibited superior permeability (76.7 L m−2 h−1 bar−1) due to its expanded pore size (1.60 nm). It integrated nanoconfinement and surface catalysis, improving the availability of surface-bound sulfate radicals for rapid Orth-P generation (kobs, 1.93 s−1), with the kobs being 2.4 times higher than that of the NCNT membrane catalytic system and 2626 times higher than the NCNT@GO heterogeneous catalytic system. The NCNT@GO-M also demonstrated excellent antifouling, self-cleaning, and anti-interference ability, effectively retaining humic acid with a molecular weight exceeding 3.6 kDa (∼62% removal of dissolved organic carbon), making it suitable for real-water applications. The development of LNCM shows great potential for transforming and recovery of the nutrients in wastewater.

Interface Engineering of MOF-Derived Co3O4@CNT and CoS2@CNT Anodes with Long Cycle Life and High-Rate Properties in Lithium/Sodium-Ion Batteries.

Metal-organic framework materials can be converted into carbon-based nanoporous materials by pyrolysis, which have a wide range of applications in energy storage. Here, we design special interface engineering to combine the carbon skeleton and nitrogen-doped carbon nanotubes (CNTs) with the transition metal compounds (TMCs) well, which mitigates the bulk effect of the TMCs and improves the conductivity of the electrodes. Zeolitic imidazolate framework-67 is used as a precursor to form a carbon skeleton and a large number of nitrogen-doped CNTs by pyrolysis followed by the in situ formation of Co3O4 and CoS2, and finally, Co3O4@CNTs and CoS2@CNTs are synthesized. The obtained anode electrodes exhibit a long cycle life and high-rate properties. In lithium-ion batteries (LIBs), Co3O4@CNTs have a high capacity of 581 mAh g-1 at a high current of 5 A g-1, and their reversible capacity is still 1037.6 mAh g-1 after 200 cycles at 1 A g-1. In sodium-ion batteries (SIBs), CoS2@CNTs have a capacity of 859.9 mAh g-1 at 0.1 A g-1 and can be retained at 801.2 mAh g-1 after 50 cycles. The unique interface engineering and excellent electrochemical properties make them ideal anode materials for high-rate, long-life LIBs and SIBs.

Dimetallic praseodymium-cobalt carbon nanotubes as highly efficient electrocatalyst for oxygen reduction reaction

In this study, six bimetallic rare earth (RE = La, Ce, Pr, Nd, Sm, Eu) cobalt nitrogen doped carbon nanotubes (RECo-NCNTs) were synthesized with g-C3N4 derivative method. These RECo-NCNTs were characterized by SEM, BET, XPS, XRD and Raman. In addition, their catalytic performances for oxygen reduction reaction (ORR) had also been tested. The introduction of rare earths did not destroy the structure of nanotubes but apparently change their ORR performances. The PrCo-NCNTs showed the significant improvement in catalytic ability for ORR (onset potential of 0.95 V and half-wave potential of 0.79 V), which is very close to that of commercial 20 % Pt/C. Moreover, PrCo-NCNTs exhibits an excellent catalytic stability (no activity decay after 10000st cycles) and an outstanding methanol toxic tolerance. Assembled in metal–air batteries (Zn-air, Al-air and Mg-air), the PrCo-NCNTs electrode also presents high power densities and discharge voltages.

Controllable fabrication of N-doped carbon nanotubes coated Co4N nanoparticles to boost hydrogen evolution reaction

Transition metal nitrides (TMNs) have attracted great attention as ideal active materials in the field of electrocatalysts in recent years due to their excellent electrical conductivity, wide band gap and adjustable morphology. Pure phase Co4N nanoparticles encapsulated nitrogen-doped carbon (NC) nanotubes (Co4N@NC) were in-situ synthesized by one-pot method. In this paper, the morphology of carbon nanotubes is controlled by adjusting the pyrolysis time, so that more active sites are exposed on carbon nanotubes. Thus, the cobalt nitride catalyst with excellent catalytic performance for hydrogen evolution reaction (HER) in acidic electrolyte was obtained. In summary, due to the protection of mesoporous nitrogen-doped carbon to Co4N nanoparticles, large electrochemically active surface area, good conductivity and more exposed active sites, Co4N@NC possesses excellent HER performance in acidic electrolytes. The overpotential of Co4N@NC at the current density of 10 mA cm−2 is 117 mV (η10), and it shows long-term stability in 0.5 M H2SO4 solution for 50 h. This study provides a strategy for the development of catalysts for the controllable synthesis of high-performance transition metal nitrides.

Engineering d-band center of cobalt active sites via dual coordination with nitrogen-doped carbon nanotube and Ti3C2Tx MXene toward electrocatalytic oxygen reduction for H2O2 production

Manipulating the selective adsorption of oxygen-containing species is crucial for tailoring the electrocatalyst to select dual-electron pathway in the oxygen reduction reaction (2e- ORR). Herein, dual-coordination electrocatalyst structure (Co-NCNT/MXene) is proposed based on the modulation of oxygenated species adsorption by coordination microenvironment at the interface of metal nanocatalysts. The Co-NCNT/MXene achieves excellent H2O2 selectivity (95.25 %), yield (162 mg L-1h−1) and Faraday efficiency (94.81 %) for ORR, surpassing the most Co-based-electrocatalysts. In-situ EPR techniques reveal the selective *OOH desorption dynamic process on Co-NCNT/MXene. Density functional theory calculations confirm that asymmetric coordination of Co nanoparticles by oxygen-terminated Ti3C2-MXene and NCNT modulates the delocalized state of Co extranuclear electrons, resulting in a reduction of the d-band center of Co, thus turning the adsorption energy of *OOH within the Co-NCNT/MXene interface towards a path more conducive to H2O2 electrosynthesis. In-situ H2O2 generated in the ORR is applied to achieve excellent degradation of organic pollutants.

A universal synthesis strategy for facile and scalable of magnetic biochar composite materials for PMS activation: Catalytic mechanisms

Biochar-based catalysts have shown great promise for application in AOPs due to their wide source and good performance, while its development is limited by its complicated preparation process and large variation in performance. Herein, a series of magnetic biochar composites(Fe@NC-XX) based on different biomass (duckweed, shrimp shell, peanut shell, corncob, and pomelo peel) were fabricated via one-pot pyrolysis method. The removal of sulfadiazine (SDZ) by all materials reached more than 90% within 20 min. The characterization results indicated that the special structure of Fe encapsulated in nitrogen-doped carbon nanotubes (CNTs) was the main reason why this approach is not limited to specific biomass. Acts as a catalytic center, Fe catalyzes the formation of CNTs during annealing. Meanwhile, graphene sheets and carbon nanoparticles formed by melamine and biomass decomposition migrate to the nucleus surface to form a hollow structure of CNTs. In addition, the results of quenching experiments and ESR tests elucidated that surface-bound radicals accumulated on the surface of CNTs, which can remarkably boost the efficient removal of SDZ. Consequently, the synthetic strategy of Fe nanoparticles anchored in N-doped CNTs that are not selective for biomass provides a new pathway for a universal synthesis method of biochar-based catalysts.

ZnO–ZrO2 coupling nitrogen-doped carbon nanotube bifunctional catalyst for co-production of diesel fuel and low carbon alcohol from syngas

Catalytic syngas conversion to liquid fuel is pivotal for biomass utilization, enhancing energy security, reducing carbon emissions and curbing reliance on petroleum imports. Herein, bifunctional catalysts comprising zinc-zirconium dioxide (ZnZrO2) dispersed on nitrogen-doped multi-walled carbon nanotubes (NCNT) (ZnZrO2/NCNT) were successfully designed, enabling the simultaneous production of both diesel fuels (C9–C16 hydrocarbon) and methanol through direct syngas conversion. Operating at 450 °C, 4.5 MPa, a gas hourly space velocity (GHSV) of 4800 mL h−1·gcat−1, the ZnZrO2/NCNT catalyst, featuring 2.6% nitrogen doping, exhibited exceptional performance, achieving a 50.3% selectivity for C9–C16 hydrocarbons and a 26.4% selectivity for methanol, while maintaining a 52.5% single-pass CO conversion rate. The C9+ selectivity significantly surpasses the bottleneck predicted by the ASF distribution theory (C9+ selectivity <36%). This starkly contrasts that of ZnO/NCNT (1.7% C9–C16 and 6.3% methanol) and ZrO2/NCNT (32.5% C9–C16 and 25.4% methanol) catalysts. Moreover, the ZnZrO2/NCNT catalyst still retained C9+ 51.5% selectivity and 25% methanol selectivity after 100 h of continuous operation. The synergistic effects resulting from the amalgamation of highly active nanostructured units with a well-encapsulation structure efficiently hinder active component migration during catalysis. This significantly enhances both the catalyst's activity and stability. Furthermore, nitrogen introduction serves as a key electron donor to ZnZrO2, thereby catalyzing the activation of CO dissociation. This activation step emerges as a pivotal factor crucial for enhancing selectivity in liquid fuel production.

Mechanism of NCNTs Growth on Foamed Nickel and Thus-Prepared PS Hydrogenation High-Performance Carrier NCNTs@FN.

Traditional heterogeneous catalysts are affected in the catalytic hydrogenation of PS by the scale effect, viscosity effect, adhesion effect, and conformational effect, resulting in poor activity and stability. Monolithic Pd-CNTs@FN catalysts could eliminate or weaken the impact of these negative effects. We grew nitrogen-doped carbon nanotubes (NCNTs) on monolithic-foamed nickel (FN) and investigate their growth mechanism. Meanwhile, the feasibility of using the NCNTs@FN carrier for PS hydrogenation reaction was also verified. The growth of NCNTs on FN can be divided into 3 stages: initial growth stage, stable growth stage, and supersaturation stage. Finally, a three-layer structure of NCNT layer, dense carbon layer, and FN skeleton is formed. Two types of structures, nickel-doped carbon nanotubes (NiCNTs) and C-Ni alloy, are formed by combining C and Ni, while four nitrogen-doped structures, NPD, NPR, NG, and NO, are formed by C and N. The prepared carrier exhibited an extremely outstanding specific surface area (2.829 × 106 cm2/g) and strength (no NCNTs falling off after 24 h 500 rpm agitation), as well as high catalytic activity for PS hydrogenation after loaded with Pd (2.13 ± 0.95 nm), with a TOF of up to 27.6 gPS/(gPd•h). After 8 repetitions of the catalyst, there was no significant decrease in activity. This proves the excellent performance of Pd-NCNTs@FN in polymer hydrogenation reactions, laying a solid foundation for further research on the mechanism of NCNTs promoting PS hydrogenation and regulating the growth of NCNTs.

An ultrasensitive electrochemical immunosensor based on meso-PdN NCs and Au NPs/N-CNTs for quantitative cTnI detection

Electrochemical immunosensors have gained considerable attention in detecting human disease markers due to their excellent specificity, high sensitivity, and facile operation. Herein, a rational-designed sandwich-type electrochemical immunosensor is constructed for the sensitive detection of cardiac troponin I (cTnI) using nitrogen-doped carbon nanotubes loaded with gold nanoparticles (Au NPs/N-CNTs) as substrate and highly active mesoporous palladium-nitrogen nanocubes (meso-PdN NCs) as secondary antibody markers. Benefitting from its large specific surface area (638.04 m2 g−1) and high nitrogen content, novel polydopamine (PDA)/ halloysite nanotubes (HNTs) hybrid derived one-dimensional (1D) N-CNTs can provide more binding sites for the in-situ growth of Au NPs to connect Ab1. Furthermore, as an ideal substrate material, Au NPs/N-CNTs exhibit finely tuned mesoporous structures and outstanding conductivity, which facilitate the mass and electron transfer during the electrocatalysis process. Besides, highly concave surfaces and crystalline mesopores of meso-PdN NCs expose more surfaces and crevices, providing abundant reactive sites for H2O2 reduction. Remarkably, the as-obtained immunosensor presented a wide linear range (from 10 fg mL−1 to 100 ng mL−1) and an excellent low detection limit (9.85 fg mL−1). This study may offer new insights into the precise fabrication of efficient electrochemical immunosensors for various clinical diagnosis applications.

Nitrogen-doped carbon nanotube encapsulated Co9S8 composite cathode for high-selective capacitive extraction of uranium (VI) from radioactive wastewater

Selective extraction of uranium [U(VI)] from uranium containing nuclear wastewater is of great significance in alleviating the uranium resources shortages and eliminating the radioactive radiation. Benefited by the merits of cost-effectiveness and environment-friendliness, capacitive deionization (CDI) shows a great promise towards selective removal of U(VI). However, exploring novel electrode materials with high intrinsic affinity rather than the excessive assistance of external means faces challenges. Herein, a nitrogen-doped carbon tube encapsulated Co9S8 composite (CS-NCNT) was developed as a Faradic cathode for selective electrosorption of U(VI) from radioactive wastewater. This work mainly emphasized on these following results: (i) The electrochemical redox activity and high surface-controlled ratios endowed the optimized CS-NCNT-2 electrode a maximum electrosorption capacity (189 mg g−1) towards U(VI). (ii) Except that CS-NCNT-2 exhibited excellent selective electrosorption performance in U(VI)-containing spiked real seawater, an ultrahigh selectivity coefficient of 707 (UO22+ over Na+) was also achieved at a Na+: UO22+ molar ratio of 200. (iii) The valence state analysis and molecular dynamic simulation revealed the essence of the reversible electrosorption-desorption process and the preferable extraction towards UO22+ compared with Na+ ions, respectively. Overall, this work can be potentially expanded to other metal chalcogenides-based electrode materials for selective removal of UO22+ even other radionuclide in U(VI)-containing radioactive wastewater.