Three-dimensional Carbon Nanotube Research Articles

Electrochemical reductive removal of trichloroacetic acids by a three-dimensional binderless carbon nanotubes/ CoP/Co foam electrode: Performance and mechanism

Numerous chlorinated disinfection by-products (DBPs) are produced during the chlorination disinfection of water. Among them, chloroacetic acids (CAAs) are of great concern due to their potential human carcinogenicity. In this study, effective electrocatalytic dechlorination of trichloroacetic acids (TCAA), a typical CAAs, was achieved in the electrochemical system with the three-dimensional (3D) self-supported CoP on cobalt foam modified by carbon nanotubes (CNT/CoP/CF) as the cathode. At a 10 mA cm−2 current density, 74.5% of TCAA (500 μg L−1) was converted into AA within 100 min. In-situ growth of CoP increased the effective electrochemical surface area of the electrode. Electrodeposited CNT promoted electron transfer from the electrode surface to TCAA. Therefore, the production of surface-adsorbed atomic hydrogen (H*) on CNT/CoP/CF was improved, further resulting in excellent electrochemical dechlorination of TCAA. The dechlorination pathway of TCAA proceeded into acetic acids via direct electronic transfer and H*-mediated reduction on CNT/CoP/CF electrode. Additionally, the electroreduction efficiency of CNT/CoP/CF for TCAA exceeded 81.22% even after 20 cycles. The highly efficient TCAA reduction performance (96.57%) in actual water revealed the potential applicability of CNT/CoP/CF in the complex water matrix. This study demonstrated that the CNT/CoP/CF is a promising non-noble metal cathode to remove chlorinated DBPs in practice.

Tailoring Interfaces of All-Carbon Electromagnetic Interference Shielding Materials for Boosting Comprehensive Performance.

Electromagnetic interference (EMI) shielding materials with lightweight, high shielding effectiveness, excellent chemical stability, especially minimized secondary electromagnetic pollution, are urgently desired for integrated electronic systems operating in harsh working environments. Here in this study, by systematically engineering and matching the interfacial properties of carbon-based membrane materials, i.e., graphite paper, whisker carbon nanotube paper (WCNT paper), carbon nanotube film (CNT film), bucky paper (BP), and carbon cloth (CC) with three-dimensional (3D) porous carbon nanotube sponge (CNTS), we successfully constructed a series of multifunctional all-carbon EMI shielding materials, which exhibit excellent average shielding effectiveness of over 90 dB with a thickness of about 1 mm and dramatically minimized secondary electromagnetic reflection. Moreover, benefiting from the all-carbon nature and engineered interfaces, our CMC materials also exhibit excellent photothermal and Joule heating performances. These results not only provide guidance for designing advanced multifunctional all-carbon EMI shielding materials but also shed light on the hidden mechanism between interfaces and performances of composite materials.

Doped Micron Silicon and Mxene Based Composite Anodes for High-Performance Li-Ion Batteries

With the world's energy needs constantly increasing, renewable energy sources must be technologically advanced and integrated with energy storage devices to ensure their uninterrupted operation. In recent decades, researchers have devoted substantial efforts to improve the energy density of lithium-ion batteries (LIBs) [1]. While graphite remains the commercial anode in LIBs, it’s very low theoretical capacity (372 mAh g-1) restricts its use in high-energy applications. Silicon (Si), owing to its high theoretical capacity of 4200 mAh g-1, natural abundance, and appropriate Li uptake potential (0.4 V vs Li/Li+), is a promising anode material [2]. However, its massive volume expansion restricts its practical use.In this study, micron-sized Si particles are combined with graphite. Micron Si is less expensive, and the synthesis process is simpler. The well-ground mixture (Si-G) is mixed with a polymer solution to generate pyrolytic carbon (upon carbonising). This aids in the buffering of mechanical stresses caused by Si volume expansion. Furthermore, direct exposure of Si to the electrolyte is avoided, stabilising the solid electrolyte interphase (SEI). The addition of a dopant improves the intrinsic conductivity of the material, resulting in increased capacity by providing electron and Li-ion transport channels. To further enhance the composite's performance, synthesized Mxene is added to promote the charge transport between micron Si. Using various techniques such as SEM-EDAX, XRD, Raman, and XPS spectroscopy, the composite's morphology and structure is studied which reveals uniformly distributed Si, C, and Mxene sheets that retain the sheet architecture.As an anode, the composite exhibits outstanding electrochemical performance which was evident by its impressive lithium storage specific capacity of 2003 mAh g-1 (based on weight of Si) even after long term cycling (at 1C rate). Additionally, the composite demonstrates superior rate performance with a specific capacity of 2439 mAh g-1 at 10 C rate, highlighting its potential for high-power applications. Moreover, the electrode displayed a low charge transfer impedance and fast electron transport, which improved the electrochemical performance. The reason for this improved performance is the unique structure consisting of Mxene and doping, which significantly increased the Li ion diffusion and the active sites. Also, low-cost micron Si is used which has a high tap density. Thus, this work provides an approach to develop high-capacity LIBs based on silicon. Keywords: Lithium-ion battery, micron silicon anode, Mxene, doping. References Liu, L. Kang, J. Hu, E. Jung, J. Zhang, S.C. Jun, Y. Yamauchi, Unlocking the Potential of Oxygen-Deficient Copper-Doped Co 3 O 4 Nanocrystals Confined in Carbon as an Advanced Electrode for Flexible Solid-State Supercapacitors, ACS Energy Lett. 6 (2021) 3011–3019. https://doi.org/10.1021/acsenergylett.1c01373.Zhou, Y. Liu, C. Du, Y. Ren, T. Mu, P. Zuo, G. Yin, Y. Ma, X. Cheng, Y. Gao, Polyaniline-encapsulated silicon on three-dimensional carbon nanotubes foam with enhanced electrochemical performance for lithium-ion batteries, Journal of Power Sources. 381 (2018) 156–163. https://doi.org/10.1016/j.jpowsour.2018.02.009.

Three-dimensional Architecture of Carbon Nanotube Transistors with High Speed and Performance

Transistors, essential components of contemporary electronics, are crucial in providing electricity for the technology-dependent society. Given the continuously growing need for enhanced speed capabilities in electronic devices, it has become crucial to investigate innovative materials and structures to fulfill these demands. Carbon Nanotubes (CNTs) have emerged as a desirable contender due to their remarkable electrical characteristics, characterized by elevated carrier mobility and nanoscale dimensions. This study explores the importance of high-speed performance in the contemporary technology-driven environment and emphasizes the crucial role played by transistors in attaining this objective. This research underscores the distinctive attributes of CNTs, including their exceptional electrical conductivity, mechanical robustness, and dimensions, making them a highly suitable contender for advanced transistors in future applications. The current transistor layouts encounter notable obstacles in effectively using the whole capabilities of CNTs, such as the difficulty associated with achieving accurate alignment and addressing connection concerns. To tackle the issues, this study presents a novel three-dimensional CNT Architecture (3D-CNTA) design that utilizes state-of-the-art Computer-Aided Design (CAD) software to achieve accurate spatial modeling. The 3D-CNTA that has been suggested exhibits exceptional performance in several aspects, encompassing power consumption (0.3 Watts), noise (2.6 microvolts), delay (6.6 nanoseconds), gain (36.25 dB), energy efficiency (2.13 femtojoules per transition), and simulation accuracy (95%).

CNTs/PVA Composite Aerogel for Efficient Microwave and Acoustic Absorption

The lightweight three-dimensional (3D) carbon nanotubes (CNTs) aerogel has garnered significant interest due to their exceptional characteristics, including high porosity, large specific surface area, and a 3D conductive network. These characteristics make it as a promising candidate for various applications in microwave absorption. However, to construct a multifunctional framework, that can swiftly adapt to complex real-world environments, remains a large challenge. In this study, we fabricated a multifunctional CNTs/polyvinyl alcohol composite aerogel (CPA). Integrating polyvinyl alcohol (PVA) into CNTs aerogel could effectively prevent CNTs aggregation, thus obtaining the remarkable electromagnetic absorption, acoustic, mechanical, and thermal properties. The minimum reflection loss (RL) of CPA achieved an outstanding value of -39.77 dB, measured with a thickness of 2 mm. In addition, CPA showed excellent sound absorption performance, with the highest sound absorption coefficient (SAC) of 0.981. Sound transmission loss (STL) could be improved by adjusting the ratio of CPA, the improvement of STL was 5-8 dB at the mid-high frequencies. Finally, CPA also exhibited excellent thermal insulation performance with the lowest thermal conductivity of 0.0297 W/m·k. The multifunctional capabilities of CPA position it as a highly promising material for various applications, such as microwave absorption, noise reduction, and heat preservation.

Three-dimensional nanostructured Co2VO4-decorated carbon nanotubes for sodium-ion battery anode materials

Three-dimensional nanostructured Co2VO4-decorated carbon nanotubes for sodium-ion battery anode materials

High performance flexible lithium-ion battery anodes: Carbon nanotubes bridging bamboo-shaped carbon-coated manganese oxide nanowires via carbon welding

Free-standing electrodes will significantly improve the specific capabilities of LIBs and reduce manufacturing costs; importantly, the introduction of the carbon protective layer can solve the problem of capacity attenuation. Herein, a novel closely crosslinked three-dimensional carbon nanotubes (CNTs) network bridge bamboo-shaped carbon-coated MnO (CCMC) flexible film anode is designed. For this design, the carbon layer can provide high electrical conductivity while buffering the volume changes of the MnO nanoparticles during repeated cycling. Meanwhile, the CNTs are also highly conductive and bridged between bamboo-shaped carbon-coated MnO (MC) to support the entire structure, effectively improving the tensile strength and structural stability of CCMC. In addition, the CCMC flexible film electrode as the anode material of flexible LIBs, does not use conductive agent, binder and collector, shows excellent electrochemical properties, including a high-rate capability of 909 mAh g−1 at 0.1 A g−1 and 406 mAh g−1 at 5.0 A g−1, and a long cycling stability (411 mAh g−1 at 0.5 A g−1 after 1000 cycles).

A flexible carbon nanotube film modified with gradient lithiophilic Cu2O/Cu heterojunction for dendrite-free lithium metal anodes

Lithium (Li) metal batteries have been extensively studied for their high energy density, but uncontrolled Li dendrites and severe volume fluctuation significantly limit their commercial applications. To address this issue in Li metal anodes, a flexible self-supporting film was developed by integrating Cu2O/Cu heterojunction with a gradient distribution and a three-dimensional (3D) single-walled carbon nanotube (SWCNT) network. The top-down gradient distribution of Cu2O/Cu effectively reduces the Li+ concentration polarization and conductivity polarization in the vertical direction within the 3D framework, achieving bottom-up deposition of Li inside the framework. Moreover, Mott-Schottky junction between lithiophilic Cu2O and Cu can trigger the built-in electric field (BIEF) at their heterointerfaces, thereby accelerating electron transfer and Li+ migration. Benefiting from the physicochemical bidirectional regulation, the Cu2O/Cu@SWCNT/Li realizes an ultralow voltage polarization of 13 mV and a prolonged cycling stability over 1800 h in a symmetric cell (1 mA cm−2 and 1 mAh cm−2). Additionally, the film shows excellent cycle stability in the Cu2O/Cu@SWCNT-Li//LiFePO4 full cell, providing practical ideas for the subsequent design of lithium metal anodes.

Structural and dimensional engineering of three-dimensional carbon nanotube/polydimethylsiloxane composite for stretchable sensor

A highly sensitive strain sensor is essential for the wearable electronic in constantly emerging applications such as human motion monitoring, personalized healthcare, human-machine interaction, soft robot and smart skin. However, most of the physical sensors currently reported are facing with challenges of non-adjustable sensing performance, unsatisfactory linearity, complicated preparation processes, and small working ranges, which greatly restricts their practical applicability. In this work, we proposal a facile technology base on the structural and dimensional engineering of carbon nanotube (CNT) conducting networks, to fabricate the flexible and stretchable strain sensor with tunable sensitivity and superior linearity in a wide sensing range. The three-dimensional CNT frameworks with adjustable density were constructed by the chemical vapor deposition method, which were used as the filler network to prepare the flexible CNT/polydimethylsiloxane (CNT/PDMS) composites. The resultant strain sensors base on the CNT/PDMS composites can realize the tunable sensitivities (gauge factor ranges from 0.7 to 233 at 100 % strain) by simply changing and regulating the structural density and macro-size of sensing strips. Meanwhile, the obtained sensors possess excellent linearity (R2 > 90 %) and repeatability on the 10 000 cycles. The technology developed in this work will offer a wide range of practical applications in wearable electronics field.

Three-dimensional graphene cross-linked carbon nanotube doping as cathode for aqueous zinc ion batteries

Aqueous zinc ion batteries (ZIBs) are becoming increasingly popular in the field of energy storage due to their high safety and environmental friendliness. This study comparatively investigated the electrochemical performance of β-MnO2 as a cathode for ZIBs after doping with different ratios of three-dimensional graphene (3D-GPE)/carbon nanotube (CNT) cross-linked composite materials with ball milling. The results show that 3D-GPE/CNT cross-linked composite has an effect on β-MnO2 microstructure and particle morphology. The cathode made of β-MnO2/(3D-GPE/CNT) with a mass ratio of 9:1 has a very high reversible capacity of 1078.93 mAh/g at a current density of 10 mA g−1, which is about 2.24 and 1.87 times the other two ratio materials (18:1 and 12:1), respectively. After 100 cycles, the median voltage difference of the β-MnO2/(3D-GPE/CNT) mass ratio 9:1 specimen battery increased. The higher the median voltage, the higher the energy of the battery. The improvement of cathode performance is directly related to the micro-state, such as the three-dimensional frameworks and carbon nanotube structures of 3D-GPE/CNT, and the macro-state, such as particle refinement, homogenization, and layered structure.

Boosting Thermoelectric Power Factor of Carbon Nanotube Networks with Excluded Volume by Co-Embedded Microparticles.

Carbon nanotube (CNT) networks embedded in a polymer matrix have been extensively studied as a flexible thermoelectric transport medium over the recent years. However, their power factor has been largely limited by the relatively inefficient tunneling transport at junctions between CNTs and the low-density conducting channels throughout the networks. This work demonstrates that significant power factor enhancements can be achieved by adding electrically insulating microscale particles in three-dimensional CNT networks embedded in the polymer matrix. When silica particles of a few μm diameters were co-embedded in single-walled CNT (SWCNT)-polydimethylsiloxane (PDMS) composites, both the electrical conductivity and the Seebeck coefficient were simultaneously enhanced, thereby boosting the power factor by more than a factor of six. We found that the silica microparticles excluded a large volume of the composite from the access of CNTs and caused CNT networks to form around them with the polymer as a binder, resulting in improved network connectivity and alignment of CNTs. Our theoretical calculations based on junction tunneling transport for three-dimensional CNT networks show that the significant power factor enhancement can be attributed to the enhanced tunneling with reduced junction distance between CNTs. Additional power factor enhancement by a factor of three was achieved by sample compression, which further reduced the mean junction distance to enhance tunneling but also reduced the geometric factor at the same time, limiting the enhancement of electrical conductivity.

A rapid and scalable fabrication of flexible P/C-CNTs anodes for sodium-ion battery

Flexible sodium-ion batteries (SIBs) are a prior energy supply for the future wearable electronic devices. And red phosphorus (P) with high theoretical capacity (2596 mAh/g) is regarded as an optimal candidate for SIB anode. However, the huge volume expansion of red P during the sodiation/desodiation process deteriorates the structural integrity of electrodes, resulting in the rapid capacity fading, which hinders the successful deployment of red P in the flexible SIB anodes. Herein, we propose a rapid and scalable method to fabricate the flexible P-based electrodes, which is similar with the common blade-coating method. The three-dimensional carbon nanotubes (CNTs) matrix from monodispersed CNT solution with robust mechanical strength ensures the structural integrity of the flexible electrode during the long cyclic process. As a result, the flexible P/C-CNTs electrode using as SIB anode delivers a reversible capacity (calculated based on the whole mass of the electrodes, 35 wt% P in electrode) of 442 mA h g−1 at 0.5 A g−1 after 100 cycles, together with 83 % capacity retention. And this work could propel the practical application process of flexible SIB.

Single-atom Zn with nitrogen defects on biomimetic 3D carbon nanotubes for bifunctional oxygen electrocatalysis

Single atoms catalysts (SACs) have promising development in electrocatalytic energy conversion. Nevertheless, rational design SACs with reversible oxygen electrocatalysis still remain challenge. Herein, we synthesized atomically dispersed Zn with N defect on three-dimensional (3D) biomimetic carbon nanotubes by secondary pyrolysis (Zn-N-C-2), which possesses excellent oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional catalytic activities. The biomimetic 3D structure and unique “leaf-branch” system are beneficial to fully expose the active sites. Density functional theory (DFT) calculations show that Zn-N3-D can optimize the charge distribution and facilitate electron transfer step of OH*→O*. Zn-N-C-2 exhibits higher ORR activity than commercial Pt/C with a half-wave potential (E1/2) of 0.85 V and OER overpotential of 450 mV at 10 mA cm−2. After being assembled into the air cathode of aqueous Zn-air battery (ZAB), it demonstrates superior performances with long-term charge and discharge for more than 200 h. This work not only clarifies the controlled synthesis of N-defects Zn SACs with excellent bifunctional electrocatalyst, but also provide in-depth understanding of structural-performance relationships by regulating local microenvironments.

Designing carbon nanotube sponge/Au@MgO2 for surface-enhanced Raman scattering detection and fenton-like degradation of organic pollutants

With the acceleration of industry and agriculture process, the massive emission of organic pollutants is a major problem which seriously restricts the sustainable development of society. Rapid enrichment, efficient degradation and sensitive detection are three key steps to solve the problem of organic pollutants, while developing a simple method integrating the above three capabilities is still a challenge. Herein, a three-dimensional carbon nanotube sponge decorated with magnesium peroxide and gold nanoparticles (CNTs/Au@MgO2 sponge) was prepared for surface enhanced Raman scattering (SERS) detection and degradation of aromatic organics by advanced oxidation processes. The CNTs/Au@MgO2 sponge with porous structures adsorbed molecules rapidly through π-π and electrostatic interaction, thus more aromatic molecules were driven to the hot-spot areas for highly sensitive SERS detection. A detection of limit with 9.09 × 10−9 M was achieved for rhodamine B (RhB). The adsorbed molecules were degraded by an advanced oxidation process utilizing hydrogen peroxide produced by MgO2 nanoparticles under acidic condition with 99% efficiency. In addition, the CNTs/Au@MgO2 sponge exhibited high reproducibility with the relative standard deviation (RSD) at 1395 cm−1 of approximately 6.25%. The results showed the sponge can be used to effectively track the concentration of pollutants during the degradation process and maintain the SERS activity by re-modifying Au@MgO2 nanomaterials. Furthermore, the proposed CNTs/Au@MgO2 sponge demonstrated the simultaneous functions of enrichment, degradation, and detection for aromatic pollutants, thus significantly expanding the potential applications of nanomaterials in environmental analysis and treatment.

Facile design of sea cucumber-like MOF-derived Fe-Co bimetallic autocatalytic carbon nanotube composites with enhanced microwave absorption properties

Thin properties and efficient absorption performance are two significant factors in the practical application of electromagnetic wave absorbers, but still face considerable conflicts. Three-dimensional (3D) Carbon Nanotube (CNTs) interpenetrating network structure has been proved to be an effective strategy to obtain high performance electromagnetic waves (EMW) absorption materials. We report a 3D sea cucumber-like nanomaterial that uses pyrolysis to self-grow CNTs on the surface of bimetallic metal-organic frameworks (MOFs). FeCo bimetallic MOF were successfully prepared and CNTs were grown after the pyrolysis of bimetallic MOF. The excellent EMW absorption performance of FeCo/CNTs composites was attributed to its multiple absorption mechanism. Electromagnetic analysis showed that the 3D structure increases the multiple reflections of the EMW and the CNT produces sufficient polarization effects. The interconnection of CNTs provides more opportunities for electron leap and electron hopping. When the matched thickness is 1.38 mm, the performance of EMW absorption properties showed a minimum reflection loss of − 59.24 dB at 17.10 GHz. Moreover, the ultrathin FeCo/CNTs composites could reach an effective absorption of 10.96 GHz (60.9% of 2–18 GHz) showing an ultra-wide absorption. This work provided options for the modification of MOFs derivatives as excellent candidates for EMW absorbers.

Encapsulation of CoS2 nanoparticles in 3D star-like N-doped graphitized carbon/carbon nanotubes nanocomposites for the detection of hydrazine in human urine and food

The design and construction of an efficient electrochemical hydrazine sensor is of great significance for food quality and safety detection. Herein, a novel three-dimensional (3D) hexagonal star-like carbon nanotubes modified N-doped graphitized carbon encapsulated CoS2 nanocomposites (CoS2 @NC/CNTs) was prepared using cobalt and zinc zeolitic imidazolate frameworks (CoZn-ZIF) as a precursor. The "tip effect" of the hexagonal star-like structure facilitates electron transfer and mass transfer. Carbon nanotube-modified N-doped graphitized carbon substrates (NC/CNTs) avoid agglomeration of CoS2 nanoparticles and have excellent electrical conductivity and abundant active sites. The above synergistic effects enable the CoS2 @NC/CNTs-based hydrazine electrochemical sensors to exhibit enhanced electrocatalytic activity compared to the conventional 3D ZIF-derived dodecahedral CoS2 @NC. As an electrochemical hydrazine sensor, CoS2 @NC/CNTs can provide a wide linear range of 1.0 μM - 6.0 mM, an excellent sensitivity of 2101 μA mM−1 cm −2, a detection limit as low as 96 nM (S/N = 3), a satisfactory stability and a promising selectivity. In addition, the sensor displays encouraging performance in the detection of hydrazine in biological and food samples, which lights up a new field for the application of such catalysts in electrochemical sensing.

Synergistic enhanced Zinc-ion battery performance achieving by atomic layer deposition of TiO2 on three-dimensional carbon nanotube network decorated Zn anode

Herein, we report a unique synergistic effect between carbon nanotube (CNT) network and atomic layer deposition (ALD) of TiO2, which not only enhances the ability to capture zinc ions but also suppresses Zn dendrite growth, resulting in uniform deposition of zinc ions during repeated cycles. The CNTs with luxuriant three-dimensional skeleton structure can provide plentiful deposition sites on Zn metal anode, which significantly reduces the nucleation overpotential and improves the reaction kinetics. Meanwhile, the TiO2 can repeatedly guide the uniform deposition of Zn owing to the excellent zincophilic. The deposition mechanism of zinc in the modified anode (TiO2CNT@Zn anode) is fully explained by comparing different carbon materials. The TiO2CNT@Zn anode shows a high Zn plating/stripping reversibility with an ultralow nucleation overpotential and achieves an ultralong lifespan over 2000 h with a voltage hysteresis of 22.5 mV compared to bare zinc (BZ) anode (63.7 mV) at a high current density of 5 mA cm−2. Moreover, the TiO2CNT@Zn anode maintains a highly stable Coulombic efficiency of 98.9% for more than 500 h. Moreover, the Zn-MnO2 battery with the TiO2CNT@Zn anode shows remarkably enhanced cycling stability.

Interfacial engineered PANI/carbon nanotube electrode for 1.8 V ultrahigh voltage aqueous supercapacitors

Flexible three-dimensional interconnected carbon nanotubes on the carbon cloth (3D-CNTs/CC) were obtained through simple magnesium reduction reactions. According to the Nernst equation, the cell voltage based on these pure carbon electrodes without any additives could reach 1.5 V due to the higher di-hydrogen evolution over potential in neutral 3.5 M LiCl electrolytes. In order to improve the electrochemical performance of the electrodes, 3D-CNTs/CC electrodes covered with polyaniline barrier layer (3D-PANI/CNTs/CC) were prepared by in situ electropolymerization using interfacial engineering method. The assembled symmetric supercapacitors display a broadened voltage of 1.8 V, high areal capacitance of 380 mF cm−2, outstanding areal energy density of 85.5 μWh cm−2 and 84% of its initial capacitance after 20 000 charge-discharge cycles. This work demonstrated that the interface engineering strategy provides a promising way to improve the energy density of carbon-based aqueous supercapacitors by widening the voltage and boosting the capacitance simultaneously.

Carbon-Coated Si Nanoparticles Anchored on Three-Dimensional Carbon Nanotube Matrix for High-Energy Stable Lithium-Ion Batteries

An easy and scalable synthetic route was proposed for synthesis of a high-energy stable anode material composed of carbon-coated Si nanoparticles (NPs, 80 nm) confined in a three-dimensional (3D) network-structured conductive carbon nanotube (CNT) matrix (Si/CNT@C). The Si/CNT@C composite was fabricated via in situ polymerization of resorcinol formaldehyde (RF) resin in the co-existence of Si NPs and CNTs, followed by carbonization at 700 °C. The RF resin-derived carbon shell (~10 nm) was wrapped on the Si NPs and CNTs surface, welding the Si NPs to the sidewall of the interconnected CNTs matrix to avoid Si NP agglomeration. The unique 3D architecture provides a highway for Li+ ion diffusion and electron transportation to allow the fast lithiation/delithiation of the Si NPs; buffers the volume fluctuation of Si NPs; and stabilizes solid–electrolyte interphase film. As expected, the obtained Si/CNT@C hybrid exhibited excellent lithium storage performances. An initial discharge capacity of 1925 mAh g−1 was achieved at 0.1 A g−1 and retained as 1106 mAh g−1 after 200 cycles at 0.1 A g−1. The reversible capacity was retained at 827 mAh g−1 when the current density was increased to 1 A g−1. The Si/CNT@C possessed a high Si content of 62.8 wt%, facilitating its commercial application. Accordingly, this work provides a promising exploration of Si-based anode materials for high-energy stable lithium-ion batteries.

Full spectrum solar hydrogen production by tandems of perovskite solar cells and photothermal enhanced electrocatalysts

Among various methods of hydrogen production, water splitting driven by perovskite solar cell (PSC) is highly desirable due to the abundance of solar energy and low material cost. The key to achieve higher solar-to-hydrogen (STH) conversion efficiency is to reduce the overpotential of water splitting and enhance the solar energy utilization of the system. Herein, we demonstrate a photothermal enhanced oxygen evolution reaction (OER) electrocatalyst by depositing NiFe layer double hydroxide (NiFe LDH) on a three-dimensional carbon nanotubes (CNTs) scaffold. The CNTs can serve double functions, first as a conductive support of the catalyst to effectively transport charge, second as a photon absorber to induce photothermal effect to enhance OER activity. The photothermal enhancement of OER is demonstrated with infrared irradiation, part of the solar spectrum that is normally wasted in a conventional photovoltaic-electrolysis water splitting system. Based on the superior OER activity and photothermal properties, an unbiased water splitting system is constructed by integrating a CNTs@NiFe LDH//Pt/C electrochemical cell (EC) with a semitransparent perovskite solar cell (ST-PSC) mini-module in tandem configuration. The ST-PSC module provides voltage to drive water splitting and transmits infrared light to the rear CNTs@NiFe LDH electrode to induce the photothermal effect. The integrated PSC-EC system improves the STH efficiency from 11.7% to 13.2% with assistance of the photothermal effect and demonstrates a new strategy to harvest the full spectrum of solar irradiation for hydrogen production.