Carbon Core Research Articles

A nanosized photothermal responsive core-shell carbonized polymer dots based on poly(N-isopropylacrylamide) for light-triggered drug release

Core-shell nanocomposites are one of the most important achievements in the fast-growing field of nanotechnology. The combination of multi-responsive nano-shell with luminescent and photothermal core has led to promising applications in various fields such as optics, electronics and medicine. In this work, a nanosized core-shell system composed by carbonized dots core and poly(N-isopropylacrylamide) shell was developed and the photothermal triggered release of doxorubicin was demonstrated. The system was fully characterized by H1-NMR, DLS, Z-potential, AFM, optical absorption and fluorescence measurements. A photothermal conversion efficiency (η) value of about 67.9% and a doxorubicin photo-release rate value of about 1.0% min−1 were measured. Molecular dynamic (MD) simulations data were in agreement with experimental results, at 310 K the coil-to-globule transition and a consequent desorption of doxorubicin from the polymer were observed. Both the radius of gyration and the fluctuation of the distance doxorubicin-PNIPAM pointed that the temperature above the LCST and the acid pH facilitated the polymer transition. Moreover, MD simulations and experimental data suggested an influence on the lower critical solution temperature (LCST) exerted by the number of polymer chains anchored to the carbon core.

Tunable photoluminescence emission from surface-state to carbon core-state of PAMAM carbonized polymer dots and its high-sensitive detection of copper(II)

Carbon dots (CDs) are important zero-dimensional materials with excellent luminescent properties. However, the mechanism of CDs photoluminescence is still an open debate, which significantly hinders the development of CDs with desired optical properties. In this work, bright blue fluorescent carbonized 1.0 G polyamine-amine polymer dots (NCPDs) has been prepared by a simple hydrothermal method, with a quantum yield of 57 %. The dominant luminescence of the NCPDs is attributed to the surface states based on synergistic hybridization between the carbon backbones and connected functional groups at below 120 °C. Photoluminescence transforms from the surface states to the surface - carbon core states, and then to carbon core states from 120° to 150 °C. Meanwhile, the degree of carbonization increases along with the size of NCPDs growing from 1.36 to 3.20 nm, and the NCPDs present excitation-dependent emission properties. Due to the remarkable fluorescence property of NCPDs, Cu2+ determination has been carried out in the aqueous phase, and the detection limit is 9 nM, which is much lower than the international minimum standard (20 μM). NCPDs present high selectivity and sensitivity toward detecting Cu2+, and provide potential applications in detecting metal pollution in the environmental water.

Electron–phonon coupling-assisted universal red luminescence of o-phenylenediamine-based carbon dots

Due to the complex core–shell structure and variety of surface functional groups, the photoluminescence (PL) mechanism of carbon dots (CDs) remain unclear. o-Phenylenediamine (oPD), as one of the most common precursors for preparing red emissive CDs, has been extensively studied. Interestingly, most of the red emission CDs based on oPD have similar PL emission characteristics. Herein, we prepared six different oPD-based CDs and found that they had almost the same PL emission and absorption spectra after purification. Structural and spectral characterization indicated that they had similar carbon core structures but different surface polymer shells. Furthermore, single-molecule PL spectroscopy confirmed that the multi-modal emission of those CDs originated from the transitions of different vibrational energy levels of the same PL center in the carbon core. In addition, the phenomenon of “spectral splitting” of single-particle CDs was observed at low temperature, which confirmed these oPD-based CDs were unique materials with properties of both organic molecules and quantum dots. Finally, theoretical calculations revealed their potential polymerization mode and carbon core structure. Moreover, we proposed the PL mechanism of red-emitting CDs based on oPD precursors; that is, the carbon core regulates the PL emission, and the polymer shell regulates the PL intensity. Our work resolves the controversy on the PL mechanism of oPD-based red CDs. These findings provide a general guide for the mechanism exploration and structural analysis of other types of CDs.

Surface amino group modulation of carbon dots with blue, green and red emission as Cu2+ ion reversible detector

The surface functional groups of carbon dots (CDs) play a significant role in the luminescence performances, but it is still unclear about the effects of special groups on the luminescence mechanism since there are different groups on the surface of prepared CDs. Here, electrochemical method was adopted to synthesize initial CDs and graphite rods served as raw materials, and initial CDs were only modified with amino groups to regulate their surface states, which lead to the blue, green and red luminescence for the modified CDs. The amino groups with different contents are only introduced on the surface of CDs without affecting carbon core. With the increased contents of amino groups, the luminescence spectra of CDs can be successfully modulated from blue to red emission. In addition, the blue emitting carbon dots (B-CDs) have a specific response to Cu2+ ions and can be applied as a fluorescent probe to detect Cu2+ ions in the solution. Moreover, the addition of DL-serine can restore the blue emission of B-CDs quenched by Cu2+ ions. Therefore, the B-CDs have great potential application as a fluorescent reversible ion detector.

Nitrogen input enhances microbial carbon use efficiency by altering plant–microbe–mineral interactions

Microbial growth and respiration are at the core of the soil carbon (C) cycle, as these microbial physiological performances ultimately determine the fate of soil C. Microbial C use efficiency (CUE), a critical metric to characterize the partitioning of C between microbial growth and respiration, thus controls the sign and magnitude of soil C-climate feedback. Despite its importance, the response of CUE to nitrogen (N) input and the relevant regulatory mechanisms remain poorly understood, leading to large uncertainties in predicting soil C dynamics under continuous N input. By combining a multi-level field N addition experiment with a substrate-independent 18 O-H2 O labelling approach as well as high-throughput sequencing and mineral analysis, here we elucidated how N-induced changes in plant-microbial-mineral interactions drove the responses of microbial CUE to N input. We found that microbial CUE increased significantly as a consequence of enhanced microbial growth after 6-year N addition. In contrast to the prevailing view, the elevated microbial growth and CUE were not mainly driven by the reduced stoichiometric imbalance, but strongly associated with the increased soil C accessibility from weakened mineral protection. Such attenuated organo-mineral association was further linked to the N-induced changes in the plant community and the increased oxalic acid in the soil. These findings provide empirical evidence for the tight linkage between mineral-associated C dynamics and microbial physiology, highlighting the need to disentangle the complex plant-microbe-mineral interactions to improve soil C prediction under anthropogenic N input.

Unraveling the origin of photoluminescence in dual emissive biogenic carbon dot

There has been considerable interest in dual emissive carbon quantum dots because of their exciting photoluminescence properties for varied applications. This work demonstrates a dual emissive system derived from a biogenic source, betalain extracted from beetroot. Different betalain carbon dots were prepared utilizing varying temperatures and time. The photoluminescence properties of BT−CD5160 (betalain carbon dots prepared at 160 ℃ for 5 min) and BT−CD10180 (betalain carbon dots prepared at 180 ℃ for 10 mins) were investigated in detail using photoluminescence (PL) spectroscopy and time-resolved PL decay studies. Interestingly the emission spectra are different and possess multi-emissive nature owing to the involvement of different surface states on the CDs. Further the PL response of BT−CD5160and, BT−CD10180in the presence of triethylamine (TEA), an aliphatic amine and, diphenylamine (DPA), an aromatic amine was found to be different when studied for both λext < 400 nm and > 400 nm. While the emission obtained from BT−CD5160 emerges from the aromatic carbon core and also from the functional groups attached to the carbon dots’ surface, the emission in BT−CD10180 is fully governed by the surface traps and defects obtained from the functionalities present. Hence, such investigated photoluminescence studies of the origin of emission will help exploit the dual emissive behaviour of biogenic carbon dots for extensive application in ratiometric sensing and optoelectronic devices.

Back Cover: Carbon dots: An innovative luminescent nanomaterial

Carbon dots (CDs) attract a mounting interests as readily accessible, nontoxic, and relatively inexpensive carbon-based nanomaterials. This review systematically summarizes the recent developments in the structural design of CDs, including internal carbon core and external carbon shell, and related optical properties from singlet and triplet states. Their practical applications in optoelectronic devices and biology are also highlighted.

Pressure-Induced Bifurcation in the Photoluminescence of Red Carbon Quantum Dots: Coexistence of Emissions from Surface Groups and Nitrogen-Doped Cores.

Carbon quantum dots (CDs) with favorable fluorescent properties have stimulated considerable effort to modulate their photoluminescence (PL) for bioimaging and sensing. However, the fluorescent mechanisms are still only partially understood due to the diverse physicochemical properties of CDs prepared by various synthesis methods and postpreparation processes. In this report, pressure-induced bifurcation of PL is reported in red carbon quantum dots (R-CDs) for the first time. The splitting of PL into an irreversible blue-shifted peak and a reversible red-shifted peak under pressure suggests the coexistence of multiple fluorescent mechanisms in R-CDs, i.e., emissions from surface groups and nitrogen-doped cores. The concentration and excitation laser energy dependencies of pressure-induced bifurcation, as well as the time-resolved PL, further support the coexistence of multiple emitters. Our results provide a method for distinguishing between the different fluorescent mechanisms related to surface groups and carbon cores in CDs.

One-step green synthesis of oil-dispersible carbonized polymer dots as eco-friendly lubricant additives with superior dispersibility, lubricity, and durability

Chemical functionalization provides effective protocols for inorganic nanomaterials as oil-dispersible lubricant additives. Nevertheless, harsh reaction conditions and arduous post-processing are frequently encountered when adopting this approach. Herein, four types of carbonized polymer dots (CPDs) with admirable dispersibility and long-term stability (more than 6 months without any sediments) in polyethylene glycol (PEG200) were synthesized by a one-step and green solvothermal route using saccharides as the single precursors. The tribological behaviors of CPDs as the lubricant additives of PEG200 were systematically evaluated and compared, confirming that the anti-wear and friction-reducing performances of PEG200 can be effectively enhanced after blended with CPDs. Clarified by the friction evaluations and worn surface detections, the superior lubricity and durability of CPDs-c are mainly attributed to the synergy between the interfacial adsorption of polymeric shells, the nano-lubrication effects of carbon cores, and the establishment of CPDs-inserted tribofilm with a uniform thickness of about 86 nm. This work explores a green and facile strategy for synthesizing the CPDs toward oil lubrication and reveals the lubrication mechanism of CPDs, which facilitates the practical application of CPDs in tribology.

Biobased PET from lignin using an engineered cis, cis-muconate-producing Pseudomonas putida strain with superior robustness, energy and redox properties

Polyethylene terephthalate (PET), the most common synthetic polyester today, is largely produced from fossil resources, contributing to global warming. Consequently, sustainable sources must be developed to meet the increasing demand for this useful polymer. Here, we demonstrate a cascaded value chain that provides green PET from lignin, the world's most underutilized renewable, via fermentative production of cis, cis-muconate (MA) from lignin-based aromatics as a central step. Catechol, industrially the most relevant but apparently also a highly toxic lignin-related aromatic, strongly inhibited MA-producing Pseudomonas putida MA-1. Assessed by 13C metabolic flux analysis, the microbe substantially redirected its carbon core fluxes, resulting in enhanced NADPH supply for stress defense but causing additional ATP costs. The reconstruction of MA production in a genome-reduced P. putida chassis yielded novel producers with superior pathway fluxes and enhanced robustness to catechol and a wide range of other aromatics. Using the advanced producer P. putida MA-10 catechol, MA could be produced in a fed-batch process from catechol (plus glucose as additional growth substrate) up to an attractive titer of 74 g L−1 and a space-time-yield of 1.4 g L−1 h−1. In terms of co-consumed sugar, the further streamlined strain MA-11 achieved the highest yield of 1.4 mol MA (mol glucose)−1, providing a striking economic advantage. Following fermentative production, bio-based MA was purified and used to chemically synthetize the PET monomer terephthalic acid and the comonomer diethylene glycol terephthalic acid through five steps, which finally enabled the first green PET from lignin.

Carbon Dots in Bioimaging, Biosensing and Therapeutics: A Comprehensive Review

Carbon dots (CDs), comprising crystalline graphitized carbon cores and polymer surface groups, are currently attracting a lot of interest in biological fields owing to their fluorescent properties, high photostability, biocompatibility and low toxicity. In addition, the easy preparation and functionalization of CDs stimulate the development of CDs‐based composite materials with specific functions. Presently, the biological applications of CDs are growing at a remarkable speed, justifying the need for up‐to‐date review articles that capture recent progress in this blossoming field. In this review, breakthroughs in the synthesis, modification, optical properties, toxicology and biocatalytic platforms of CDs are described. Further, recent research related to bioimaging, biosensing, drug delivery, antibacterial, anticancer (photothermal therapy, photodynamic therapy and synergistic therapy) and antiviral therapies involving CDs are discussed in detail. Finally, a perspective on the prospects and challenges of CDs in the fields of biomedicine and biotechnology is provided.

2,2,2-Trifluoroethanol-mediated hydroarylation of fluorinated alkynes with indoles: Application to diindolylmethanes.

A new mild and practically simple alkyne hydroarylation protocol for the synthesis of 3-(indol-3-yl)-3-(trifluoromethyl)acrylic acid esters by the reaction of indole derivatives with ethyl/methyl 4,4,4-trifluoro-3-(indol-3-yl)but-2-enoates in trifluoroethanol was developed. This method has the following advantages: no catalyst, atom economy, high yields, broad substrate scope, and large-scale synthesis. The potential application of this protocol was further demonstrated by the synthesis of a variety of CF3 -substituted synthons and a new class of (un)symmetrical 3,3'-diindolylmethanes with a quaternary carbon core that might be biologically active.

Seagrasses and local environment control the bacterial community structure and carbon substrate utilization in brackish sediments

Seagrasses are complex benthic coastal ecosystems that play a crucial role in organic matter cycling and carbon sequestration. However, little is known about how seagrasses influence the structure and carbon utilization potential of benthic bacterial communities. This study examined the bacterial communities in monospecific and mixed meadows of seagrasses and compared with bulk (unvegetated) sediments from Chilika, a brackish water coastal lagoon of India. High-throughput sequencing of 16S rRNA genes revealed a vegetation effect in terms of differences in benthic bacterial community diversity, composition, and abundances in comparison with bulk sediments. Desulfobacterales, Chromatiales, Enterobacteriales, Clostridiales, Vibrionales, and Acidimicrobiales were major taxa that contributed to differences between seagrass and bulk sediments. Seagrasses supported ∼5.94 fold higher bacterial abundances than the bulk due to rich organic carbon stock in their sediments. Co-occurrence network demonstrated much stronger potential interactions and connectedness in seagrass bacterial communities compared to bulk. Chromatiales and Acidimicrobiales were identified as the top two keystone taxa in seagrass bacterial communities, whereas, Dehalococcoidales and Rhizobiales were in bulk communities. Seagrasses and local environmental factors, namely, water depth, water pH, sediment salinity, redox potential, total organic carbon, available nitrogen, sediment texture, sediment pH, and sediment core depth were the major drivers of benthic bacterial community composition. Carbon metabolic profiling revealed that heterotrophic bacteria in seagrass sediments were much more metabolically diverse and active than bulk. The utilization of carbon substrate guilds, namely, amino acids, amines, carboxylic acids, carbohydrates, polymers, and phenolic compounds was enhanced in seagrass sediments. Metabolic mapping predicted higher prevalence of sulfate-reducer and N2 fixation metabolic functions in seagrass sediments. Overall, this study showed that seagrasses control benthic bacterial community composition and diversity, enhance heterotrophic carbon substrate utilization, and play crucial roles in organic matter cycling including degradation of hydrocarbon and xenobiotics in coastal sediments.

Temperature induced transformation of Co@C nanoparticle in 3D hierarchical core-shell nanofiber network for enhanced electromagnetic wave adsorption

Developing high-performance electromagnetic wave absorbing materials (EWAMs) with tunable nano-microstructures is of great significance for solving increased electromagnetic radiation pollution. Three-dimensional hierarchical networks within magnetic metal nanoparticles are promising candidates with the great balance of enhanced electromagnetic wave attenuation and impedance matching, but hard to construct. Herein, a two-step electrospinning/in-situ self-assembly strategy was employed, successfully synthesizing a 3D hierarchical core-shell NC@Co/NC nanofiber network (NC@Co/NC-900). The N-doped Carbon (NC) core fibers (diameter of ∼250 nm) built a 3D-conductive network, while the Co@C nanoparticles (diameter of ∼20 nm) embedded into N-doped Carbon (Co/NC) shell (thickness of ∼50 nm) enhanced the polarization loss and magnetic loss. More importantly, the controlled transformation of Co@C nanoparticles in the shell was realized by modulating the calcination temperature at 900 °C, showing an optimal homogeneously dispersion in a narrow particle size distribution in the range of 15–25 nm. Uniformly multiple reflection in core-shell NC@Co/NC-900 fiber network enhanced the electromagnetic wave attenuation with the optimal impedance matching, displaying excellent RLmin of −55.82 dB at 11.60 GHz and wide EAB of 7.44 GHz in a low filler loading of 15 wt %. The whole X and Ku bands could be fully covered in different thickness of 4.0 and 3.0 mm. This work presents a superior nano-micro structural design strategy on 3D hierarchical networks with multiple reflections.

Surface ionization-induced tunable dynamic phosphorescence colors from carbon dots on paper for dynamic multimode encryption

Stimuli-responsive phosphorescence materials with dynamic color-changing properties are highly promising for advanced information security. Herein, we demonstrate a novel strategy that effectively induces tunable dynamic phosphorescence color from carbon dots (CDs) on papers via surface ionization engineering for multimode encryption and information storage. Alkali-induced phenolic hydroxyl ionization on CDs can boost intersystem crossing rates, while surface-ionized groups with negative charges significantly passivate the surface defects and reduce non-radiative transitions, which can activate surface state-related blue phosphorescence emission. Combined with the carbon core state-related yellow-green phosphorescence, excitation/time-dependent phosphorescence color-changing from yellow-green to blue are realized from alkali (Na2CO3) treated CDs on paper. Furthermore, benefiting from the transition from NaHCO3 to Na2CO3 under thermal treatment, dynamic color-changing phosphorescence can also be activated by thermally stimulating NaHCO3-treated CDs on paper. Finally, multi-stimuli (alkali or thermal) and multi-modal dynamic phosphorescent colors from a single CDs system are realized for the first time. Based on these unique features, multimode encryption and smart 3D codes with anti-counterfeiting and monitoring functions for medicine during transport or storage are demonstrated by combining an inkjet printing technique using CD inks.

Core-shell heterogeneous graphene-based aerogel microspheres for high-performance broadband microwave absorption via resonance loss and sequential attenuation

Graphene-based aerogels have been attracted wide attention in microwave absorption (MA) for their lightweight and high-efficient absorption. However, the assembly design of their shape and structure is still lacking, bringing obstacles to the optimization of MA. Herein, we applied coaxial electrospinning to shape aerogel monoliths into aerogel microspheres (AMs) with core–shell bilayer structure, exhibiting distinguishing broadband and tunable high‐performance MA. The composite AMs including reduced oxide graphene/Fe3O4 shell layer and chitosan derived carbon core layer ([email protected]/Fe3O4) can be achieved via coaxial electrospinning-freeze frying followed by calcination. The core–shell structure can make electromagnetic wave sequential entry and attenuate, enhancing the impedance matching and electromagnetic wave propagation. Significantly, with a low loading of 5 wt%, the core–shell AMs exhibit a minimum reflection loss of − 61 dB at 13.84 GHz with the thickness of 2.5 mm, and the effective absorption bandwidth reach 6.88 GHz. More importantly, the corresponding absorption bandwidth is further widened to 7.52 GHz by adjusting the core–shell ratio. Electromagnetic simulation further indicate the core–shell bilayer coupling including electromagnetic wave sequential attenuation and cavity resonance loss can realize the enhanced broadband MA. The core–shell bilayer structure strategy paves a way to achieve graphene-based aerogel absorbers with high‐performance MA.

Fluorescent Mechanism in Zero-Dimensional Carbon Nanomaterials: A Review.

Fluorescent carbon dots (CDs) have acquired growing interest from different areas over decades. Their fascinating property of tunable fluorescence by changing the excitation wavelength has attracted researchers worldwide. Understanding the mechanisms behind fluorescence is of great importance, as they help with the synthesis and applications, significantly when narrowed down to applications with color-tunable mechanisms. But, due to a lack of practical and theoretical information, the fluorescence mechanisms of CDs remain unknown, preventing the production of CDs with desired optical qualities. This review focuses on the PL mechanisms of carbon dots. The quantum confinement effect determined the carbon core, the surface and edge states determined by various surface defects and the connected functional/chemical groups on the surface/edges, the molecular state solely determined the fluorophores in the interior or surface of the CDs, and the Crosslink Enhanced Emission Effect are the currently confirmed PL mechanisms.

Boosting Capacitive Deionization Performance of Commercial Carbon Fibers Cloth via Structural Regulation Based on Catalytic‐Etching Effect

Monolithic carbon electrodes with robust mechanical integrity and porous architecture are highly desired for capacitive deionization but remain challenging. Owing to the excellent mechanical strength and electroconductivity, commercial carbon fibers cloth demonstrates great potential as high‐performance electrodes for ions storage. Despite this, its direct application on capacitive deionization is rarely reported in terms of limited pore structure and natural hydrophobicity. Herein, a powerful metal‐organic framework‐engaged structural regulation strategy is developed to boost the desalination properties of carbon fibers. The obtained porous carbon fibers features hierarchical porous structure and hydrophilic surface providing abundant ions‐accessible sites, and continuous graphitized carbon core ensuring rapid electrons transport. The catalytic‐etching mechanism involving oxidation of Co and subsequent carbonthermal reduction is proposed and highly relies on annealing temperature and holding time. When directly evaluated as a current collector‐free capacitive deionization electrode, the porous carbon fibers demonstrates much superior desalination capability than pristine carbon fibers, and remarkable cyclic stability up to 20 h with negligible degeneration. Particularly, the PCF‐1000 showcases the highest areal salt adsorption capacity of 0.037 mg cm−2 among carbon microfibers. Moreover, monolithic porous carbon fibers‐carbon nanotubes with increased active sites and good structural integrity by in‐situ growth of carbon nanotubes are further fabricated to enhance the desalination performance (0.051 mg cm−2). This work demonstrates the great potential of carbon fibers in constructing high‐efficient and robust monolithic electrode for capacitive deionization.

Synthesis and photoluminescence properties of orange-red carbon dots from the paper tissues as the precursor.

In recent years, stable and photoluminescence (PL) tunable fluorescent materials known as carbon dots (CDs) have seen rapid development. Here, a simple, low-cost, and environmentally friendly approach has been developed to synthesize the orange-red CDs (OR-CDs) with paper tissues as the precursor in the presence of ethanol and concentrated sulfuric acid. The average diameter of the OR-CDs was measured at around 1.25 nm. The as-prepared OR-CDs are composed of carbon cores with the graphite structure distributed in the middle and wrapped or entangled by polymers for the outside. Moreover, the PL characteristics of the OR-CDs under the dilute solution state and the concentrated solution state, respectively, were explored. The former with the blue light showed prominent excitation-dependent characteristics in the range from 365 to 420 nm; the latter rendered the excitation-independent property with distinguished orange-red fluorescence emission. With an increase in the concentration, the emission fluorescence intensities gradually increased under the excitation wavelength of 540 nm, which can be attributed to the aggregation-induced emission property of the OR-CDs. By virtue of their excellent PL properties and low toxicity, we believe that the OR-CDs have potential applications in various optoelectronic areas, especially in white LED fields.

FeOx@graphitic carbon core–shell embedded in microporous N-doped biochar activated peroxydisulfate for removal of Bisphenol A: Multiple active sites induced non-radical/radical mechanism

The development of novel carbocatalysts with high activity and stability is important for the rapid degradation of emerging pollutants. Fe/N co-doped biochar (FeOx@GC-NBC) was innovatively synthesized with a pyrolytic carbonization method and then used as a functional peroxydisulfate (PDS) activator to degrade Bisphenol A (BPA). FeOx@GC-NBC with an optimized Fe/N ratio modification exhibited 23.16 and 8.65-fold great activity for BPA removal compared to pristine BC and N-doped BC, respectively. Approximately 93% of total organic carbon (TOC) could be removed in the heterogeneous activation system. We attributed theexcellent performance of FeOx@GC-NBC to the following attributes: i) a microporous carbon matrix with larger specific surface area (1691.81 m2·g−1) was favorable for adsorption, exposure of catalyst active sites (e.g., Fe-Nx, Graphitic N) and electron-transfer; ii) the C–O–Fe bond and highly core–shell structure of graphitic nanosheets (FeOx@GC) enhanced the N retention ability and durability of the catalyst; iii) organics adsorption dominated by a “pore-filling and π-π interaction” mechanism effectively promoted BPA oxidation. In acidic and neutral solutions, the radical oxidation (SO4•–and •OH) processes were responsible for BPA decomposition. In alkaline solution, electron transfer, instead of 1O2 or a high-valent iron species, was the dominant pathway. This study proposes a simple and feasible strategy to synthesize the FeOx@GC-NBC catalyst, which provides insights into catalyst design and the internal active sites involved in the purification mechanism of refractory organics.