Carbon Nanoshells Research Articles

Engineering peripheral S-doped atomic Fe-N4 in defect-rich porous carbon nanoshells for durable oxygen reduction reaction and Zn-air batteries

Iron-nitrogen-carbon (Fe-N-C) single-atom materials have emerged as the most promising catalysts for the oxygen reduction reaction (ORR), which yet suffers from inadequate stability arising from the attack of ·OH and HO2· radicals generated by H2O2. In this study, density functional theory (DFT) calculations reveal that the presence of peripheral S atoms can regulate the electronic structure of the Fe center and suppress the formation of H2O2 to enhance the catalyst's durability. Thereafter, atomic Fe-N4 with peripheral S doping is intricately engineered in defect-rich porous carbon nanoshells (Fe-NS-C) through an adsorption-pyrolysis method. The incorporation of S not only optimizes the coordination microenvironment of Fe-N4 but also induces a larger specific surface area and richer defects. The Fe-NS-C catalyst displays remarkable ORR performance, featuring a half-wave potential (E1/2) of 0.90 V. Its low H2O2 yield (below 1.1 %) and excellent stability (10 mV day in E1/2 after 10,000 cycles) further underscore the superiority of Fe-NS-C. When employed as the cathode for Zn-air battery, Fe-NS-C achieves an impressive peak power density of 230.1 mW cm−2 and stable charge/discharge potentials over an extended duration of 150 h. This study presents an effective strategy for engineering efficient and durable single-atom electrocatalysts for ORR and Zn-air batteries.

Internal Space Modulation of Yolk-Shell FeSe2@Carbon Anode with Peanut-Shaped Morphology Enabling Ultra-Stable and Fast Potassium-Ion Storage.

The poor cycling stability and rate performance of transition metal selenides (TMSs) are caused by their intrinsic low conductivity and poor structural stability, which hinders their application in potassium-ion batteries (PIBs). To address this issue, encapsulating TMSs within carbon nanoshells is considered a viable strategy. However, due to the lack and uncontrollability of internal void space, this structure cannot effectively mitigate the volume expansion induced by large K+, resulting in unsatisfactory electrochemical performance. Herein, peanut-shaped FeSe2@carbon yolk-shell capsules are prepared by modulation of the internal space. The active FeSe2 is encapsulated within a robust carbon shell and an optimal void space is retained between them. The outer carbon shell promotes electronic conductivity and avoids FeSe2 aggregation, while the internal void mitigates volume expansion and effectively ensures the structural integrity of the electrode. Consequently, the FeSe2@carbon anode demonstrates exceptional rate performance (242 mAh g-1 at 10 A g-1) and long cycling stability (350 mAh g-1 after 500 cycles at 1 A g-1). Furthermore, the effect of internal space modulation on electrochemical properties is elucidated. Meanwhile, ex situ characterizations elucidate the K+ storage mechanism. This work provides effective guidance for the design and the internal space modulation of advanced TMSs yolk-shell structures.

Unveiling the dual tunability of dimension and pore structure in MAX-derived carbon via molten salt electrolysis

3D construction or pore-forming of carbon nanosheets brings the materials exceptional energy storage performance. However, these strategies involve complicated procedures and challenging conditions. Herein, based on the structural regulation of a MAX phase, a facile method was proposed to prepare MAX-derived carbon (MDC) with dual tunability of dimension and pore structure via molten salt electrochemical etching-gaseous sulfur delamination coupling. Polyhedral structure Ti2SC and highly oriented structure Ti2SC were transformed into 3D Mesopore carbon nanoshells (3D Meso-CNSL) and 2D Mesopore carbon nanosheets (2D Meso-CNST) in one step. By matching the decomposition voltage of TiClx with that of PS-Ti2SC, Cl2 gas generated in situ was employed to enhance the porosity of the 3D Meso-CNSL, resulting in the formation of 3D meso/macro-porous carbon nanoshells (3D Meso/Macro-CNSL) with doubled pore volume (1.45 cm3 g−1) and specific surface area (649.97 m2 g−1). The 3D Meso/Macro-CNSL exhibits excellent capacity performance and cycle stability under high current density. The capacities are 674.8 mAh g−1 and 501.5 mAh g−1 after 1000 cycles at 5 A g−1 and 10 A g−1, respectively. It is the first report on the direct delamination of MAX phases into 3D nanomaterials, presenting a new pathway for the precise regulation of the nanostructure of the MDCs.

In-situ confining selenium within bubble - like carbon nanoshells for ultra-stable Li-Se batteries.

Lithium-selenium (Li-Se) batteries are promising energy storage devices. However, the long-term durability and high-rate performance of the Se cathode have been limited by significant volume expansion and the troublesome shuttle effect of polyselenides during repeated charging/discharging processes. To revolutionize these issues, we applied a top-down strategy through the in-situ trapping of amorphous Se within bubble-like carbon (BLC) frameworks, which can radically minimize the presence of surface-absorbed Se while enhancing Se loading capacity. This ingenious technique successfully encapsulates all Se species within carbon nanoshells, creating a distinct half-filled core-shell structure known as Se@void@BLC. This in-situ trapping approach ensures the efficient management of Se volume changes during repeated discharge and charge cycles. Moreover, an extraordinary Se loading capacity of up to 65.6 wt% is reached. Using the Se@void@BLC as cathode for Li-Se battery, we achieve a high initial Columbic efficiency of 84.2 %, a high reversible capacity of 585 mAh g-1 , and an ultralow capacity decay of only 0.0037 % per cycle during 4000 cycles at 10 A g-1 .

Cubic-like SnO2/ZnS Hollow Heterojunction Encapsulated in Carbon Nanoshell as Cathode for Advanced Aluminum Batteries

Cubic-like SnO₂/ZnS Hollow Heterojunction Encapsulated in Carbon Nanoshell as Cathode for Advanced Aluminum Batteries

Carbon-shell-encapsulated gold–palladium nanoreactors for highly efficient 5-hydroxymethylfurfural oxidation: Confinement and alloy effects study

Encapsulating noble metal nanoparticles in carbon nanoshells is an emerging and efficient way to enhance the activity and stability of noble metal species. A novel type of hollow rod-shaped carbon-shell-encapsulated gold–palladium (AuPd) alloy nanoreactor (AumPdn@CT) was designed and constructed. The Au2Pd1@C800 nanoreactor afforded a satisfactory 2,5-furandicarboxylic acid (FDCA) yield of 99.9 % from 5-hydroxymethylfurfural (HMF) oxidation using O2 as the oxidant in water. Remarkably, carbon-shell-encapsulated only 1.0 wt% AuPd alloy could offer an outstanding FDCA formation rate of 2003.6 mmol·g−1·h−1. Mechanistic studies demonstrated that the generated confinement and AuPd alloy species not only improved the adsorption capacity of the HMF substrate and the key intermediate 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), but also facilitated the adsorption and activation of molecular oxygen to generate oxygen active species of superoxide radicals. Constructing a carbon shell around AuPd alloy active sites provided effective physical protection for the metal core, thus enhancing the catalyst stability and reusability.

Ruthenium nanoparticles incorporated hollow carbon nanoshells for improved hydrogen evolution reaction

The development of efficient and stable catalyst is crucial for hydrogen evolution reaction (HER) in water electrolysis. The rational design of porous supports can effectively improve the exposure of active sites and increase the electrochemically active surface area of catalysts. In this study, a nanostructured carbon nanoshell (CS) is proposed for the synthesis of ruthenium and nitrogen incorporated carbon catalyst (CS@N-Ru) catalysts. Physicochemical characterization show that the prepared catalyst exhibits a hollow structure and abundant nitrogen/ruthenium related active sites, which enables the improvement of mass transfer and the catalytic activity. The electrochemical tests show that the prepared CS remarkably facilitates the performance of catalyst, the CS@N-Ru500 synthesized at 500 °C exhibits the best catalytic activity with a low overpotential of 35 mV at 10 mA/cm2 and Tafel slope of 38 mV/dec, attributing to the increased electrochemically active surface area, reduced electron/ion transfer resistance, and accelerated kinetics of HER. These findings suggest that the CS@N-Ru can be a promising alternative to Pt/C for HER in water electrolysis.

Enhanced mechanical properties of nanocrystalline B4C–SiC composites by in-situ high pressure reactive sintering

A unique optimized of core–shell structural B4C nanopowder, sintering aid additive of Si, and high-pressure sintering technique has been used to process nanocrystalline B4C–SiC ceramics with enhanced mechanical properties. C-coated B4C nanopowder was initially uniformly mixed with micron Si of different content by ball-milling. B4C–SiC composites with a homogenous distribution of SiC in B4C matrix were subsequently obtained by sintering the mixed powders at 6 GPa and 1600 °C. The added Si reacted with submicron amorphous carbon layer and amorphous carbon nanoshell to form dispersed SiC nanocrystals and Si–C phase filled at B4C grain boundaries and pores, respectively. The prepared composite had the most outstanding mechanical properties when the Si content in the precursor was 15 wt%, with a hardness reaching 37.8 GPa and a fracture toughness reaching 7.3 MPa·m1/2. Microstructural characterizations indicated that the multi deflection of nanoscale crack caused by intergranular fracture, the covalent bonding of Si–C phase at the grain boundary, and the abundant nanotwin substructure were jointly responsible for the superior performance in hardness and fracture toughness.

Influence of alloying and surface overcoating engineering on the electrochemical properties of carbon-supported PtCu nanocrystals

Designing nanostructured Pt-based materials with unique properties as electrocatalyst attracts great research interests to achieve clean and sustainable energy. Herein, we investigate nanoscale engineering of carbon-supported PtCu nanocrystals (NCs) through tailoring their electronic and geometry properties by means of alloying and surface overcoating. Alloying Pt with Cu enhances the catalytic efficiencies for the acidic hydrogen evolution reaction (HER). Subsequent surface overcoating of PtCu nanostructures with carbon nanoshells endows a decreased mass activity towards the HER catalysis compared to the uncoated counterparts, this can be mainly associated with annealing-induced sintering of small metal nanoparticles and the surface site-blockage of metal active sites. These results indicate that breaking activity-stability trade-off remains to be challenging for efficient HER catalysis on carbon-supported PtCu nanostructures. Our case study on the limitations of fabricating PtCu nanodendrites with varied loadings of carbon nanoshells on the surface demonstrates the necessity to explore the design of advanced and high-performing metal-based catalysts.

Enhanced electromagnetic wave absorption, thermal conductivity and flame retardancy of BCN@LDH/EP for advanced electronic packing materials

The limited functionalization of current electronic packaging materials has restricted their use in advanced smart electronic devices with high energy density and low signal delay. In this study, we propose a novel strategy for developing an electronic packaging material (BCN@LDH/EP) that possesses exceptional electromagnetic wave (EMW) absorption, thermal management, and flame-retardant capabilities. BCN@LDH/EP is the double-level hollow core–shell structure (BCN@LDH) composed of a bowl-shaped carbon nanoshell (BCN) and a layered double hydroxide (NiAl-LDH). This structure offers rich heterogeneous interfaces and high specific surface area, thereby generating abundant polarization sites and favorable impedance matching. Consequently, the epoxy resin (EP) shows outstanding EMW absorption performance, with a maximum effective absorption band (EAB) of 6.43 GHz and a minimum reflection loss (RL) value of −55.75 dB at a filling amount of only 10 wt%. Moreover, the closely packed thermally conductive filler BCN@LDH provides a broad pathway for heat transfer within the EP, resulting in a significant thermal conductivity improvement efficiency (η) of ∼170%. Notably, the high-temperature cooling and barrier effects of BCN@LDH also confer excellent flame retardancy to the EP composite, reducing the total heat release (THR) rate by up to 44.9%.

Heavily heteroatoms doped carbons with tunable microstructure as the iodine hosts for rechargeable zinc-iodine aqueous batteries

Rechargeable zinc-iodine aqueous batteries are promising energy storage technology by virtue of their natural abundance, low costs, and high safety. However, it is still restricted to the sluggish electrochemical reaction kinetics and lack of high-performance host materials. Here, four types of porous carbons including carbon nanosheets, carbon nanoshells, carbon skeletons, and carbon dodecahedrons have been produced with ZIF-8 as the precursor by simply changing the additives. Not only the morphologies but also the specific surface area as well as the pore size distributions of the resulting samples can be well regulated while maintaining a high heteroatomic content, which affords a multifunctional platform to explore the structure-electrochemical performance relationship when serving as the iodine hosts for zinc-iodine aqueous batteries. Moreover, the plentiful of heteroatomic functional groups and inorganic species can shift the weak van der Waals force between hosts and iodine species to strong chemical interaction through halogen bonds. Therefore, the maximum specific capacity can reach 313.6 mAh g−1 (at 0.5 C), good rate capability at 100 C, and long cycle life. Furthermore, the interaction between iodine and host as well as the energy storage mechanism has been explored based on s series of spectral analysis techniques. This work offers the possibility to design high-performance aqueous zinc-based batteries via the optimization of suitable carbon hosts.

A microstructure tuning strategy on hollow carbon nanoshells for high-efficient oxygen reduction reaction in direct formate fuel cells

The microstructure of carbon supports for electrocatalysts plays a crucial role in dispersing active sites, establishing oxygen/ion transport channels, and thus determining the oxygen reduction reaction (ORR) activity. A facile and simple microstructure tuning strategy is adopted to synthesize hollow carbon nanoshells (CNSs) with tuneable microstructure in this study. The CNSs with expected macroporous (300–966 nm) and mesoporous (2–5 nm) structures were achieved by adjusting heating ramp rates during pyrolysis. The CNS prepared at 1 °C min−1 (CNS-1) possesses a well-developed mesoporous/macroporous structure, which is conducive to dispersing iron phthalocyanine during the synthesis and establishing triple-phase interfaces in the catalyst layer during the ORR. Therefore, the electrocatalyst (Fe–N/CNS-1), derived from the CNSs-1, exhibits a 44 mV higher half-wave potential (0.879 V vs. RHE) in a rotating disk electrode and a 14% higher maximum power density (16.1 mW cm−2) in a membrane-less direct formate fuel cell than that of Pt/C. This study delivers a promising microstructure tuning strategy for carbon supports to construct high-efficient ORR electrocatalysts.

Collaborative integration of ultrafine Fe2P nanocrystals into Fe, N, P-codoped carbon nanoshells for highly-efficient oxygen reduction

The rational design and facile synthesis of cost-effective and high-performance carbon-based catalysts for oxygen reduction reaction (ORR) is of great significance but remain challenging. Herein, we report the crafting of a robust Fe,N,P-codoped, ultrafine Fe2P nanocrystals decorated, highly hierarchical porous carbon nanoshells (denoted Fe,N,P-CNSs/Fe2P) via a simple yet robust one-step synergetic phosphorization and pyrolysis approach for highly-efficient ORR. Specifically, well-defined polypyrrole-co-polyaniline hollow nanospheres with a shell thickness of ≈ 43 nm (PPy-co-PANI-HNs) are first elaborately synthesized via a facile soft-templating (Triton X-100 micelles) copolymerization of pyrrole and aniline monomers. Subsequent one-step synergetic phosphorization and pyrolysis of PPy-co-PANI-HNs pre-impregnated with NaH2PO2·H2O and FeCl3 (H2PO2-,Fe3+@PPy-co-PANI-HNs) yields Fe,N,P-CNSs/Fe2P with a well-crafted ultrathin nanoshell (shell thickness of ≈13 nm) architecture containing abundant hierarchical porosity. Remarkably, an alkaline electrolyte capitalizing on the resulting Fe,N,P-CNSs/Fe2P manifests excellent ORR performance with the half-wave and onset potentials (E1/2 of 0.854 V and Eonset of 0.955 V) comparable to Pt/C, diffusion limited current density (JL of −5.98 mA cm−2) higher than Pt/C, and long-time durability and methanol resistance better than Pt/C, demonstrating great potential as air cathode in zinc-air batteries (maximum power density of 170 mW cm−2 and specific capacity of 824.5 mA h g−1). Combined experimental and theoretical studies reveal that the impressive ORR performance of Fe,N,P-CNSs/Fe2P originates from simultaneous compositional (i.e., Fe,N,P-codoping and ultrafine Fe2P nanocrystals decorating) and structural (i.e., hierarchically porous ultrathin nanoshell architecture) tailoring enabled by the judicious one-step synergetic phosphorization and pyrolysis.

Facile adsorption-electroflotation method for the removal of heavy metal ions from water using carbon nanomaterials.

Due to the none-biodegradable and carcinogenic nature of toxic metal ions, a novel sorption-electroflotation method was developed using carbon nanomaterials. The metal ions removed were Ni(II), Co(II), Zn(II), Fe(II), and Cu(II) using carbon nanotubes (CNTs) and carbon nanoshells (CNSs). The porous structure, morphology, composition, and surface properties of carbon nanomaterials, viz. the presence and number of functional groups are characterized by methods of low-temperature nitrogen adsorption, scanning electron microscopy, Boem, X-ray photoelectron spectroscopy. The surface of the materials was rough with varied particle sizes. Regardless of the sorbed ion and the nature of the nanomaterial, the Langmuir, Temkin, Dubinin-Radushkevich, and Flory-Higgins models were applied to the data. The maximum sorption removal on CNTs were 15.0-69.0, 36.0-75.0, 33.0-72.0, 18.0-70.0, 29.0-69.0% for Fe(II), Zn(II), Co(II), Cu(II), and Ni(II) while these values on CNSs were 19.0-53, 23.0-58.0, 30.0-79.0, 12.0-46.0, and 41.0-86%. But after simultaneous sorption-electroflotation, the percentage removal was 99.0, 97.0, 95.0, 99.0, and 52% for these metal ions, indicating an excellent combination of sorption-electro flotation. The method is highly beneficial to work in varied pH ranges as sorption and electroflotation gave the best results in acidic and basic mediums. The method is very effective, efficient, and inexpensive and can be used for the removal of the reported metal ions in water.

Growing of ultra-thin Bi2MoO6 nanoflowers on Co/N-doped graphitic carbon nanoshells as attractive custom supports: Excellent photocatalytic degradation activity for pollutants

Ultra-thin Bi2MoO6 nanoflowers were grown on Co/N-doped graphitic carbon (Co/N-GC) nanoshells consisting of Co/N-doped layered GC to obtain Hierarchical Co/N-GC@Bi2MoO6 hollow heterostructures for visible light photocatalytic degradation of organic pollutants. The Schottky heterojunction, derived from the introduction of Co/N-GC nanoshells, could simultaneously boost photoinduced electron transport and limit photoexcited electron-hole recombination. Density functional theory (DFT) calculations, XPS, EPR methods confirmed the charge transfer mechanism of the structure, which would not only accelerate the charge separation but also improve the photocatalyst redox capability. This structural and compositional advantage accelerates charge separation and migration, as well as providing considerable surface areas and extensive reaction sites for several species of contaminant interpretation.

Engineering adjacent N, P and S active sites on hierarchical porous carbon nanoshells for superior oxygen reduction reaction and rechargeable Zn-air batteries

Heteroatom-doped carbon materials have been regarded as sustainable alternatives to the noble-metal catalysts for oxygen reduction reaction (ORR), while the catalytic performances still remain unsatisfactory. Herein, we develop a metal-free adjacent N, P and S-codoped hierarchical porous carbon nanoshells (NPS-HPCNs) through a novel layer-by-layer template coating method. The NPS-HPCNs is rationally fabricated by crosslinking of polyethyenemine (PEI) and phytic acid (PA) on nano-SiO2 template surface and subsequently coating of viscous sulfur-bearing petroleum pitch, followed by pyrolysis and alkaline etching. Soft X-ray absorption near-edge spectroscopy (XANES) analysis and density functional theory (DFT) calculations prove the engineering of adjacent N, P and S atoms to generate synergistic and reinforced active sites for oxygen electrocatalysis. The NPS-HPCNs manifests excellent ORR activity with a half-wave potential (E1/2) of 0.86 V, as well as promoted durability and methanol tolerance in alkaline medium. Remarkably, the NPS-HPCNs-based Zn-air battery delivers an open-circuit voltage of 1.479 V, a considerable peak power density of 206 mW cm−2 and robust cycling stability (over 200 h), even exceeding the commercial Pt/C catalyst. This study offers fundamental insights into the construction and synergistic mechanism of adjacent heteroatoms on carbon substrate, providing advanced metal-free electrocatalysts for Zn-air batteries and other energy conversion and storage devices.

Analytical determination of non-local parameter value to investigate the axial buckling of nanoshells affected by the passing nanofluids and their velocities considering various modified cylindrical shell theories

We analytically determine the nonlocal parameter value to achieve a more accurate axial-buckling response of carbon nanoshells conveying nanofluids. To this end, the four plates/shells’ classical theories of Love, Flügge, Donnell, and Sanders are generalized using Eringen’s nonlocal elasticity theory. By combining these theories in cylindrical coordinates, a modified motion equation is presented to investigate the buckling behavior of the nanofluid-nanostructure-interaction problem. Herein, in addition to the small-scale effect of the structure and the passing fluid on the critical buckling strain, we discuss the effects of nanoflow velocity, fluid density (nano-liquid/nano-gas), half-wave numbers, aspect ratio, and nanoshell flexural rigidity. The analytical approach is used to discretize and solve the obtained relations to study the mentioned cases.

Sintering behavior of carbon-supported Pt nanoparticles and the effect of surface overcoating

The significance of supported metal catalysts in heterogeneous catalysis calls for in-depth understanding of metal particle sintering behavior in order to rationalize the design of stable nanocatalysts. Here, we show that the sintering behavior of supported metal nanoparticles (NPs), exemplified by studying the carbon-supported Pt NPs, becomes markedly accelerated when the interparticle distance between neighboring metal NPs is shortened. Pt NPs with close proximity are prone to form aggregates and further coalescence to fewer, larger crystals under high temperature conditions. Enlarging interparticle distance on the support and engineering NP surface with overcoatings are beneficial for the preparation of sinter-resistant catalysts. The former can be achieved through reducing the metal loadings or utilizing suitable synthetic technologies that allow for the homogeneous distribution of supported metal particles. The surface overcoating engineering relied on the carbon nanoshell formed on the Pt particle surface by in situ pyrolysis of an organic polymer. The evolution of carbon nanoshell formation was visualized by in situ transmission electron microscopy measurements. We also show the potentials of surface overcoating for enhancing catalytic performance.

Anti‐Aggregation of Nanosized CoS2 for Stable K‐Ion Storage: Insights into Aggregation‐Induced Electrode Failures (Adv. Energy Mater. 29/2022)

Potassium-Ion Batteries In article number 2201259, Ming-Sheng Wang and co-workers reveal the mechanism of the aggregation of nanosized anode materials upon potassiation by in/ex-situ electron microscopies, which is found to be a crucial reason for serious electrode failures. An anti-aggregation strategy is further proposed through isolating the nanoparticles inside individual carbon nanoshells, which prevents their extensive aggregation across the electrode, resulting in superior electrochemical stability.

Construction of core-in-shell Au@N-HCNs nanozymes for tumor therapy

Noble metals act as nanozymes that can generate reactive oxygen species (ROS) by catalysis to induce apoptosis of tumor cells for cancer therapy. But they are easy to aggregate, which will affect their further application. Carbon materials are often used as the carrier of noble metals to improve their catalytic performance. However, designing a composite structure to build an efficient carbon/noble metal hybrid nanozyme with high catalytic performance for tumor therapy is still a significant challenge. In this work, a core-in-shell structure nanozyme composed of gold nanoparticles (AuNPs) embedded in nitrogen-doped hollow carbon nanoshells (AuNPs@N-HCNs) were fabricated, which exhibited peroxidase-like (POD-like) and oxidase-like (OXD-like) activity. Compared with core-out-of-shell structure composite, the AuNPs@N-HCNs showed a better ability to generate ROS to kill tumor cells. Furthermore, AuNPs@N-HCNs also exhibited satisfactory photothermal conversion properties, which helped build a platform for photothermal therapy. Meanwhile, the enzyme activity produced by AuNPs@N-HCNs increased significantly under light irradiation. Comparing the size of AuNPs in carbon shell, 15 nm AuNPs were better than 2 nm in both enzyme-like activities and in vivo therapeutic effect. In vitro and in vivo studies demonstrated that under the synergistic effect of light-enhancing nanozyme catalysis and photothermal therapy, AuNPs@N-HCNs could induce cancer cell apoptosis and destroy tumors effectively, which provided evidence for the feasibility of tumor catalytic-photothermal treatment.