Photoactive materials based on semiconducting nanocarbons——A challenge opening new possibilities for photocatalysis

This perspective paper introduces the concept that nanocarbons and related materials such as carbon dots are an interesting intrinsic photocatalytic semiconducting material, and not only a modifier of the existing (semiconducting) materials to prepare hybrid materials. The semiconducting properties of the nanocarbons, and the possibility to have the band gap within the visible-light region through defect band engineering, introduction of light heteroatoms and control/manipulation of the curvature or surface functionalization are discussed. These materials are conceptually different from the 'classical' semiconducting photocatalysts, because semiconductor domains with tuneable characteristics are embedded in a conductive carbon matrix, with the presence of various functional groups (as C=0 groups) enhancing charge separation by trapping electrons. These nanocarbons open a range of new possibilities for photocatalysis both for energetic and environmental applications. The use of nanocarbons as quantum dots and photo luminescent materials was also analysed. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

A review of nanocarbons in energy electrocatalysis: Multifunctional substrates and highly active sites

Nanocarbons are of progressively increasing importance in energy electrocatalysis, including oxygen reduction, oxygen evolution, hydrogen evolution, COreduction, etc. Precious-metal-free or metal-free nanocarbon-based electrocatalysts have been revealed to potentially have effective activity and remarkable durability, which is promising to replace precious metals in some important energy technologies,such as fuel cells, metal–air batteries, and water splitting. In this review, rather than overviewing recent progress completely, we aim to give an in-depth digestion of present achievements, focusing on the different roles of nanocarbons and material design principles. The multifunctionalities of nanocarbon substrates(accelerating the electron and mass transport, regulating the incorporation of active components,manipulating electron structures, generating confinement effects, assembly into 3 D free-standing electrodes) and the intrinsic activity of nanocarbon catalysts(multi-heteroatom doping, hierarchical structure,topological defects) are discussed systematically, with perspectives on the further research in this rising research field. This review is inspiring for more insights and methodical research in mechanism understanding, material design, and device optimization, leading to a targeted and high-efficiency development of energy electrocatalysis.

Electrocatalytic conversion of CO_2 to liquid fuels using nanocarbon-based electrodes

Recent advances on the use of nanocarbon-based electrodes for the electrocatalytic conversion of gaseous streams of CO2 to liquid fuels are discussed in this perspective paper. A novel gas-phase electrocatalytic cell, different from the typical electrochemical systems working in liquid phase, was developed. There are several advantages to work in gas phase, e.g. no need to recover the products from a liquid phase and no problems of CO2 solubility, etc. Operating under these conditions and using electrodes based on metal nanoparticles supported over carbon nanotube （CNT） type materials, long C-chain products （in particular isopropanol under optimized conditions, but also hydrocarbons up to C8-C9） were obtained from the reduction of CO2. Pt-CNT are more stable and give in some cases a higher productivity, but Fe-CNT, particular using N-doped carbon nanotubes, give excellent properties and are preferable to noble-metal-based electrocatalysts for the lower cost. The control of the localization of metal particles at the inner or outer surface of CNT is an importact factor for the product distribution. The nature of the nanocarbon substrate also plays a relevant role in enhancing the productivity and tuning the selectivity towards long C-chain products. The electrodes for the electrocatalytic conversion of CO2 are part of a photoelectrocatalytic （PEC） solar cell concept, aimed to develop knowledge for the new generation artificial leaf-type solar cells which can use sunlight and water to convert CO2 to fuels and chemicals. The CO2 reduction to liquid fuels by solar energy is a good attempt to introduce renewables into the existing energy and chemical infrastructures, having a higher energy density and easier transport/storage than other competing solutions （i.e. H2）.

Defect and Doping Co‑Engineered Non‑Metal Nanocarbon ORR Electrocatalyst

Exploring low-cost and earth-abundant oxygen reduction reaction(ORR)electrocatalyst is essential for fuel cells and metal–air batteries.Among them,non-metal nanocarbon with multiple advantages of low cost,abundance,high conductivity,good durability,and competitive activity has attracted intense interest in recent years.The enhanced ORR activities of the nanocarbons are normally thought to originate from heteroatom(e.g.,N,B,P,or S)doping or various induced defects.However,in practice,carbon-based materials usually contain both dopants and defects.In this regard,in terms of the co-engineering of heteroatom doping and defect inducing,we present an overview of recent advances in developing non-metal carbon-based electrocatalysts for the ORR.The characteristics,ORR performance,and the related mechanism of these functionalized nanocarbons by heteroatom doping,defect inducing,and in particular their synergistic promotion effect are emphatically analyzed and discussed.Finally,the current issues and perspectives in developing carbon-based electrocatalysts from both of heteroatom doping and defect engineering are proposed.This review will be beneficial for the rational design and manufacturing of highly efficient carbon-based materials for electrocatalysis.

Lymph node mapping in rabbit liver cancer with nanocarbon and methylene blue injecta

Objective:To discuss the value of lymph node mapping in rabbit liver cancer with nanocarbon and methylene blue injecta.Methods:Rabbit liver cancer model was established by transplanting VX2 cells with laparotomy in celiac planting method.Twenty Japan white rabbits were divided into two groups randomly.Each group had 10 rabbits.Lymph node mapping in (wo groups rabbit liver cancer were observed.Two groups rabbit liver cancer and local lymph nodes were removed.The number and location of local lymph nodes were recorded,and then the samples were obtained from both groups.Results:The lymph nodes dyed time was(100.50±29.92) s in nanocarbon group,and(11.20+4.18) s in methylene blue group with statistical significance between two groups(P=0.000).In the comparison of lymph node fading time,nanocarbon group was(2.22±0.74) h,methylene blue group was(1.63+0.54) h,nanocarbon group was longer than the methylene blue group,but without statistical significance(P=0.058).The accuracy was 87.5% (35/40) in methylene blue group,while,the nanocarbon group was 87.2%(34/39),with statistical significance(P=1.000).Conclusions:Experimental results show that application of nanocarbon injection and methylene blue injection during resection of liver cancer and local lymph nodes in rabbit liver cancer model has obvious tracer function in liver cancer and lymphatic drainage. It can reduce the complexity and risk of the operation,and avoid the blindness in the process of traditional lymph node dissection surgery.Besides,they can effectively reduce the number of residual lymph nodes after operation.It can achieve the lymph node dissection more thoroughly, promptly,easily and safely.

Recent developments of nanocarbon based supports for PEMFCs electrocatalysts

Nanocarbons,widely and commonly used as supports for supported Pt-based electrocatalysts in PEMFCs,play a significant role in Pt dispersion and accessibility,further determining their corresponding electrocatalytic performance.This paper provides an overview of the nanoarchitectures and surface physicochemical properties of nanocarbons affecting the electrocatalyst performance,with an emphasis on both physical characteristics,including pore structure,and chemical properties,including heteroatom doping and functional carbon-based supports.This review discusses the recent progress in nanocarbon supports,guides the future development direction of PEMFC supports,and provides our own viewpoints for the future research and design of PEMFCs catalysts,advancing the commercialization of PEMFCs.

Nanocarbon-Enhanced 2D Photoelectrodes:A New Paradigm in Photoelectrochemical Water Splitting

Solar-driven photoelectrochemical(PEC)water splitting systems are highly promising for converting solar energy into clean and sustainable chemical energy.In such PEC systems,an integrated photoelectrode incorporates a light harvester for absorbing solar energy,an interlayer for transporting photogenerated charge carriers,and a co-catalyst for triggering redox reactions.Thus,understanding the correlations between the intrinsic structural properties and functions of the photoelectrodes is crucial.Here we critically examine various 2D layered photoanodes/photocathodes,including graphitic carbon nitrides,transition metal dichalcogenides,layered double hydroxides,layered bismuth oxyhalide nanosheets,and MXenes,combined with advanced nanocarbons(carbon dots,carbon nanotubes,graphene,and graphdiyne)as co-catalysts to assemble integrated photoelectrodes for oxygen evolution/hydrogen evolution reactions.The fundamental principles of PEC water splitting and physicochemical properties of photoelectrodes and the associated catalytic reactions are analyzed.Elaborate strategies for the assembly of 2D photoelectrodes with nanocarbons to enhance the PEC performances are introduced.The mechanisms of interplay of 2D photoelectrodes and nanocarbon co-catalysts are further discussed.The challenges and opportunities in the field are identified to guide future research for maximizing the conversion efficiency of PEC water splitting.

Plasma activation towards oxidized nanocarbons for efficient electrochemical synthesis of hydrogen peroxide

Oxidized nanocarbons(ONCs)have been regarded as efficient electrocatalysts for H2O2 production.However,wet chemical procedures involving large volumes of strong acid and long synthetic time are usually needed to obtain these ONCs.Herein,a plasma activation strategy is developed as a rapid and environmentally benign approach to obtain various ONCs,including oxidized multiwalled carbon nanotubes,single-walled carbon nanotube,graphene,and super P carbon black.After a few minutes of plasma activation,oxygen-containing functional groups and defects can be effectively introduced onto the surface of nanocarbons.Enhanced electrocatalytic activity and selectivity are demonstrated by the plasma-ONCs for H2O2 production.Taking oxidized multiwalled carbon nanotubes as an example,high selectivity(up to 95%)and activity(0.75 V at 1 mA cm^(−2))can be achieved in alkaline solution.Moreover,ex situ x-ray photoelectron spectroscopy and in situ Raman measurements reveal that C–O,C=O,edge defect,and sp2 basal planar defect are probably the active sites.

Fluoridation routes,function mechanism and application of fluorinated/fluorine-doped nanocarbon-based materials for various batteries:A review

With the popularity and widespread applications of electronics,higher demands are being placed on the performance of battery materials.Due to the large difference in electronegativity between fluorine and carbon atoms,doping fluorine atoms in nanocarbon-based materials is considered an effective way to improve the performance of used battery.However,there is still a blank in the systematic review of the mechanism and research progress of fluorine-doped nanostructured carbon materials in various batteries.In this review,the synthetic routes of fluorinated/fluorine-doped nanocarbon-based(CF_x)materials under different fluorine sources and the function mechanism of CF_x in various batteries are reviewed in detail.Subsequently,judging from the dependence between the structure and electrochemical performance of nanocarbon sources,the progress of CF_x based on different dimensions(0D–3D)for primary battery applications is reviewed and the balance between energy density and power density is critically discussed.In addition,the roles of CF_x materials in secondary batteries and their current applications in recent years are summarized in detail to illustrate the effect of introducing F atoms.Finally,we envisage the prospect of CF_x materials and offer some insights and recommendations to facilitate the further exploration of CF_x materials for various high-performance battery applications.

Primary amine coupling on nanocarbon catalysts: Reaction mechanism and kinetics via fluorescence probe analysis

Non-metallic nanocarbon materials catalyzed coupling reactions of primary amines to produce imine is an efficient,green and sustainable synthetic route,which has a wide application prospect in fine chemicals or pharmaceutical molecules.In the present study,we show firstly the relatively high catalytic activity of graphene oxide in the reaction of oxidative coupling of benzylamine(OCB),which is even comparable with typical metal-based catalysts,indicating the great potential of nanocarbon materials in this reaction system.More importantly,a novel twophoton fluorescence probe molecule(N-propyl-4-hydrazinyl-1,8-naphthalimide,NA)with special chemical structure of hydrazine functionality was synthesized.The probe NA could selectively react with aldehyde or ketone compounds,leading to the photoluminescence enhancement via inhibition of photo induced electron transfer(PET)process.The synthesized NA was applied as probe in carbon catalyzed OCB system to predict the existence of reaction intermediate benzaldehyde(BA),indicating the reaction pathway of oxidation-deamination-condensation in nanocarbon catalyzed OCB process.The proposed luminescence-probe strategy for revealing the kinetics and mechanism may also shed light in other reaction systems concerning the intermediates or products of ketones or aldehydes.

The Porous Nanocarbons with Polynuclear Aromatic Cores

Three porous nanocarbons,1–3 that comprise pyrene,corannulene,and coronene cores encircled by cyclo-meta-phenylene(CMP)interconnections,have been synthesized and characterized.The interconnected CMPs caused different curvatures of the cores and imparted high solubility,large bathochromic shift,strong fluorescence,and low reduction potential to the systems.In solution,these porous nanocarbons existed as a complex mixture of dynamic processes that certainly influenced one another within any single molecule,leading to a set of rather simple proton nuclear magnetic resonance(^(1)H NMR)spectra.Single crystal X-ray diffraction and computational minimum energy analysis revealed the boatand saddle-like conformations of 1–3 in the solid state,significantly deviating from their conformations on the Au(111)surface.Furthermore,both 1 and 2 could form 2:1 complexes with C_(60),accompanied by adaptive geometry changes.In addition,1 served as a sky-blue emitter for an organic light-emitting diode(OLED).This work gives access and insights into a model system consisting of porous nanocarbons with intriguing supramolecular and optoelectronic properties.

Nanocarbon-based electrode materials applied for supercapacitors

As one of the promising energy storage and conversion systems,supercapacitors(SCs)are highly favored owing to their high power density and good service life.Among all the key components of supercapacitor devices,the design and investigation of electrode materials play an essential role in determining the whole electrochemical charge storage performance.Recently,nanocarbon-based materials(e.g.,graphene,carbon dots,graphene quantum dots,etc.)have been widely used as SC electrode materials because of their good physical structure and chemical properties,providing a new route to further improve the energy density and life span of SCs.Here,we review the latest progress of nanocarbon-based materials(including nanocarbon and nanocarbon-based composite materials)as electrode materials in SCs application.The recent progress of carbon dots,graphene,carbon nanotubes,and other nanocarbon materials electrodes is summarized,while the capacitance and energy density of the above nanocarbon electrodes still need to be improved.Then,the preparation and performance of nanocarbonbased composite electrodes comprising transition metal oxides,conductive polymer,and metal-organic framework derived porous carbon are reviewed.Finally,we outline major challenges and propose some ideas on building better nanocarbon-based SC electrodes.

Co/N co-doped graphene-like nanocarbon for highly efficient oxygen reduction electrocatalyst

The development of efficient and inexpensive graphene-based electrocatalysts is of great significance to promote the commercial application of fuel cell and metal-air batteries. In this paper, a new type of Co and N co-doped graphene-like nanocarbon(Co/N-GLC) material was prepared by nano-silicon protection and high temperature pyrolysis.The obtained Co/N-GLC catalyst not only has a similar morphology of graphene, but also possesses a high specific surface area(809 m2 g-1) with hierarchical porous structure(micropores/mesopores), and relative high active dopants content.These properties endow it with a good oxygen reduction activity in alkaline media, which can be comparable to commercial Pt/C catalyst. Moreover, the assembled zinc-air batteries using Co/N-GLC catalyst as the air electrode display a better discharge performance and higher stability compared to that of Pt/C electrode. This work demonstrates that the prepared graphene-like carbon catalyst has a good prospect,which can replace noble metal catalyst at the cathode in metalair batteries.

Electrochemical manufacturing of nanocarbons from carbon dioxide in molten alkali metal carbonate salts： roles of alkali metal cations

One simple and fast way to manufacture a useful product from CO2 is to capture the gas by, and then carry out electrolysis in molten alkali metal carbonates. Carbon electro-deposition in molten Li2CO3-Na2CO3- KaCO3 （molar ratio： 43.5：31.5：25.0） has been widely reported in literature. However, studies in each of the individual alkali metal carbonates either have received less attention or are simply lacking in literature. Electrochem- ical studies of these molten carbonates are important to understand their underlying processes and reactions during the electrolysis. In this work, cyclic voltammograms （CVs） were recorded in each of the above-mentioned molten alkali carbonate salts using a 0.25 mm diameter Pt wire working electrode. In molten Na2CO3 and K2CO3, the main cathodic reaction was likely the formation of alkali metal, while that in Li2CO3 was carbon deposition. The results also suggest that other competing reactions such as CO and alkali metal carbide formation are possible as well in dif- ferent molten salts. On the CVs, the anodic current peaks observed are mostly associated with the oxidation of cathodic products. Flake/ring/sheet-like structures and quasi-spherical particles were observed in the produced carbon. The morphology of the carbon contained both amorphous and graphitic structures, which varied with different electrolysis variables.

Porous nitrogen/halogen dual-doped nanocarbons derived from imidazolium functionalized cationic metal-organic frameworks for highly efficient oxygen reduction reaction

Heteroatom-doped carbon materials as alternative catalysts for oxygen reduction reaction(ORR)have drawn increasing attention due to their tunable chemical and electronic structures for achieving high activity and stability. However, there still remains a great challenge to fabricate porous heteroatoms dual-doped carbons with uniformly doping in a facile and controllable way. Herein,imidazole/imidazolium-functionalized metal-organic frameworks(MOFs) are employed as precursors and templates to achieve porous nitrogen and halogen dual-doped nanocarbons. Among these carbon materials, the as-prepared nitrogen/bromine dual-doped catalyst BrNC-800 exhibits the best ORR performance with a positive half-wave potential at 0.80 V(vs. RHE) in 0.1 mol L-1 KOH, which is comparable to the benchmark commercial 20 wt% Pt/C catalyst. BrNC-800 shows excellent long term stability and methanol tolerance.This work provides a facile approach to fabricate highly efficient heteroatoms dual-doped carbon catalysts for energy conversion.

Hierarchical,seamless,edge-rich nanocarbon hybrid foams for highly efficient electromagnetic-interference shielding

Lightweight,flexible,ultrahigh-performance electromagnetic-interfe rence(EMI)shielding materials are urgently required in the areas of aircraft/aerospace,portable and wearable electronics.Herein,1 D carbon nanotubes(CNT)and carbon nanofibers(CNF)with 2 D edge-rich graphene(ERG)are used to form a lightweight,flexible CNT-ERG-CNF hybrid foam.This foam was fabricated through a self-sacrificial templating chemical vapor deposition process,where nanocarbons bond through covalent bonding,forming a hierarchical 3 D hybridized carbon nanostructure.Multistage conductive networks and heterogeneous interfaces were constructed using edge-rich nanocarbons to increase the induced currents and interfacial polarization which makes great contributions to achieve high absorption electromagnetic shielding effectiveness(SEA).The CNT-ERG-CNF hybrid foam exhibits EMI shielding effectiveness(SE)exceeding55.4 dB in the X-band while the specific SE(SSE,SE divided by mass density)achieves 9200 dB cm^(3)g^(-1),which surpasses that of nearly all other carbon-based composite materials.Furthermore,the structural stability and durability of the flexible CNT-ERG-CNF hybrid foams is examined by measuring EMI SE after 10000 times cyclic bending.Remarkably,this work not only provides a new idea for preparing hierarchical carbon materials for a wide range of applications,but presents some fundamental insights for achieving higher absorption losses in EMI shielding materials.

Temperature-resistant and flexible supercapacitors based on 10-inch wafer-scale nanocarbon films

Most of the supercapacitors reported in literatures showed little or no flexibility in the working temperature around 150℃. However, the supercapacitors are generally exposed under complex system or extreme temperature, such as electric vehicles and extremely cold area. Herein, we successfully fabricated a large-scale robust nanocarbon hybrid film consisting of reduced graphene oxide (rGO), carbon nanotubes (CNTs) and MnOx nano-flowers with the size up to 550 cm^2. The mechanical properties of the hybrid films depend on the ratio o f CNTs. The supercapacitors prepared with the hybrid films exhibit high flexibility and keep their performances in a temperature range from - 20 to 200℃. In addition, the devices display remarkable electrochemical and deformation stability at extrem e temperature. This strategy has a potential for the more efficient preparation of flexible electrode materials.

Single Cu atom dispersed on S,N-codoped nanocarbon derived from shrimp shells for highly-efficient oxygen reduction reaction

Recently,Cu-based single-atom catalysts(SACs)have garnered increasing attention as substitutes for platinum-based catalysts in the oxygen reduction reaction(ORR).Therefore,a facile,economical,and efficient synthetic methodology for the preparation of a high-performance Cu-based SAC electrocatalyst for the ORR is extremely desired,but is also significantly challenging.In this study,we propose a ball-milling method to synthesize isolated metal SACs embedded in S,N-codoped nanocarbon(MNSDC,M=Cu,Fe,Co,Ni,Mn,Pt,and Pd).In particular,the Cu-NSDC SACs exhibit high electrochemical activity for the ORR with half-wave potential(E_(1/2))of 0.84 V(vs.reversible hydrogen electrode(RHE),20 mV higher than Pt/C)in alkaline electrolyte,excellent stability,and electrocatalytic selectivity.Density functional theory(DFT)calculations demonstrated that the desorption of OH*intermediates was the rate-determining step over Cu-NSDC.This study creates a pathway for high-performance ORR single atomic electrocatalysts for fuel cell applications and provides opportunities to convert biowaste materials into commercial opportunities.

Graphitized nanocarbon-supported metal catalysts:synthesis,properties,and applications in heterogeneous catalysis

Graphitized nanocarbon materials can be an ideal catalyst support for heterogeneous catalytic systems. Their unique physical and chemical properties, such as large surface area, high adsorption capacity, excellent thermal and mechanical stability, outstanding electronic properties, and tunable porosity, allow the anchoring and dispersion of the active metals. Therefore, currently they are used as the key support material in many catalytic processes. This review summarizes recent relevant applications in supported catalysts that use graphitized nanocarbon as supports for catalytic oxidation, hydrogenation, dehydrogenation, and C-C coupling reactions in liquid-phase and gas-solid phase-reaction systems. The latest developments in specific features derived from the morphology and characteristics of graphitized na- nocarbon-supported metal catalysts are highlighted, as well as the differences in the catalytic behavior of graphitized nano- carbon-supported metal catalysts versus other related cata- lysts. The scientific challenges and opportunities in this field are also discussed.

Promoting electrochemical reduction of CO_(2) to ethanol by B/N-doped sp^(3)/sp^(2) nanocarbon electrode

Electrochemical reduction of CO_(2) to value-added chemicals holds promise for carbon utilization and renewable electricity storage.However,selective CO_(2) reduction to multi-carbon fuels remains a significant challenge.Here,we report that B/N-doped sp^(3)/sp^(2) hybridized nanocarbon(BNHC),consisting of ultra-small nanoparticles with a sp^(3) carbon core covered by a sp^(2) carbon shell,is an efficient electrocatalyst for electrochemical reduction of CO_(2) to ethanol at relatively low overpotentials.CO_(2) reduction occurs with a Faradaic efficiency of 58.8%-69.1% for ethanol and acetate production at -0.5∼-0.6 V(vs.RHE),among which 51.6%-56.0% is for ethanol.The high selectivity for ethanol is due to the integrated effect of sp^(3)/sp^(2) carbon and B/N doping.Both sp^(3) carbon and B/N doping contribute to enhanced ethanol production with sp^(2) carbon reducing the overpotential for CO_(2) reduction to ethanol.