Carbon dots-derived carbon nanoflowers decorated with cobalt single atoms and nanoparticles as efficient electrocatalysts for oxygen reduction

The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐containing intermediates during the 4e–ORR offers a practical route toward improving ORR kinetics.Herein,we designed a novel ORR electrocatalyst containing Co single atoms and nanoparticles supported by carbon dots‐derived carbon nanoflowers(Co SAs/NPs CNF).Co SAs/NPs CNF possessed a very high ORR activity(E_(1/2) of the Co SAs/NPs CNF catalyst is 0.83 V(vs.RHE)),and outstanding catalytic performance and stability when used as the air‐electrode catalyst in rechargeable ZABs(152.32 mW cm^(-2),1000.58 mWh gZn^(–1),and over 1300 cycles at a current density of 5 mA cm^(-2)).The Co SAs and Co NPs cooperated to improve electron and proton transfer processes during ORR.Theoretical calculations revealed that the presence of adjacent Co NPs optimized the electronic structure of the isolated Co‐N_(4) sites,significantly lowering the energy barriers for the rate‐determining step in ORR(adsorption of*OOH)and thereby delivering outstanding ORR performance.This work reveals that the combination of supported single‐atom sites and metal nanoparticles can be highly beneficial for ORR electrocatalysis,outperforming catalysts containing only Co SAs or Co NPs.

Optimizing polymer aggregation and blend morphology for boosting the photovoltaic performance of polymer solar cells via a random terpolymerization strategy

Compared to regular conjugated polymers,the random conjugated terpolymers are usually not beneficial to achieve highly efficient non-fullerene(NF)-based polymer solar cells(PSCs)due to their disordered chemical structures.In this work,we report two random terpolymer donors(PBNB80 and PBNB50)by tuning the molar ratio of electron-accepting units of 1,3-di(thiophen-2-yl)naphtho[2,3-c]thiophene-4,9-dione(NTD)and 1,3-bis(4-chlorothiophen-2-yl)-4 H,8 H-benzo[1,2-c:4,5-c’]dithiophene-4,8-dione(ClBDD),at the same time,the parent polymers(PBNB100 and PBNB00)are also compared to study.These four polymer donors exhibit similar optical bandgaps and gradually deepen highest occupied molecular orbital levels.Importantly,aggregation and self-organization properties of the random terpolymer donors are optimized,which result in the better morphology and crystal coherence length after blending with NF acceptor of BO-4 Cl.Particularly,a PBNB80:BO-4 Cl blend forms an optimal nanoscale phase-separation morphology,thereby producing an outstanding power conversion efficiency of 16.0%,which is much higher than those(12.8%and 10.7%)of their parent binary polymer donor-based devices.This work demonstrates that rational using terpolymerization strategy to prepare random terpolymer is a very important method to achieve highly efficient NF-PSCs.

Observation of Van Hove Singularities and Temperature Dependence of Electrical Characteristics in Suspended Carbon Nanotube Schottky Barrier Transistors

A Van Hove singularity(VHS) is a singularity in the phonon or electronic density of states of a crystalline solid. When the Fermi energy is close to the VHS, instabilities will occur, which can give rise to new phases of matter with desirable properties. However, the position of the VHS in the band structure cannot be changed in most materials. In this work, we demonstrate that the carrier densities required to approach the VHS are reached by gating in a suspended carbon nanotube Schottky barrier transistor. Critical saddle points were observed in regions of both positive and negative gate voltage, and the conductance flattened out when the gate voltage exceeded the critical value. These novel physical phenomena were evident when the temperature is below 100 K. Further, the temperature dependence of the electrical characteristics was also investigated in this type of Schottky barrier transistor.

Progress on the mechanisms of Ru-based electrocatalysts for the oxygen evolution reaction in acidic media

Water electrolysis using proton-exchange membranes is one of the most promising technologies for carbon-neutral and sustainable energy production.Generally,the overall efficiency of water splitting is limited by the oxygen evolution reaction(OER).Nevertheless,a trade-off between activity and stability exists for most electrocatalytic materials in strong acids and oxidizing media,and the development of efficient and stable catalytic materials has been an important focus of research.In this view,gaining in-depth insights into the OER system,particularly the interactions between reaction intermediates and active sites,is significantly important.To this end,this review introduces the fundamentals of the OER over Ru-based materials,including the conventional adsorbate evolution mechanism,lattice oxygen oxidation mechanism,and oxide path mechanism.Moreover,the up-to-date progress of representative modifications for improving OER performance is further discussed with reference to specific mechanisms,such as tuning of geometric,electronic structures,incorporation of proton acceptors,and optimization of metal-oxygen covalency.Finally,some valuable insights into the challenges and opportunities for OER electrocatalysts are provided with the aim to promote the development of next-generation catalysts with high activity and excellent stability.

Gradual chlorination at different positions of D-π-A copolymers based on benzodithiophene and isoindigo for organic solar cells

Isoindigo(IID)has been widely used as strong acceptor unit(A)to construct narrow bandgap polymers in organic field effect transistors(OFETs)and organic solar cells(OSCs).Combing with IID,we chose benzodithiophene(BDT)as the donor unit(D)and thieno[3,2-b]thiophene(TT)as theπbridge to construct a new type of D-π-A polymer PE70.Based on PE70,we adopt the chlorination strategy to fine-tune photoelectric characteristics and film morphology,and then developed PE74 and PE75.By blending with non-fullerene acceptor(NFA)Y6,device based on PE74 with chloride substitution on the BDT unit showed increasing photovoltaic performance.In addition,further chlorine substitution on the IID(PE75)would greatly reduce the non-radiative voltage loss(ΔV3),and the distorted molecular conformation also took responsible for the excessive recombination.As results,PE74:Y6-based device achieves a power conversion efficiency(PCE)of 11.06%with open-circuit voltage(VOC)of 0.76 V,which are higher than those of PE70:Y6(PCE of 10.40%and VOC of 0.72 V)and PE75:Y6-based device(PCE of 6.24%and VOC of 0.84 V).This work demonstrates the regularity of the photovoltaic performance caused by chlorination strategy in polymer in the non-fullerene OSC devices,which provide important insights into highperformance photovoltaic materials.

Synthesis and Thermoelectric Property of 1D Flexible PEDOT: p-TSA/Glass Fiber

Exploiting the thermal insulation properties of glass fiber and excellent conductivity of conducting polymer, a novel one-dimensional (1D) composite thermoelectric material, based on poly(3,4-ethylenedioxythiophene): p-toluenesulfonic acid (PEDOT: p-TSA)/glass fiber, is prepared by coating the PEDOT: p-TSA on the surface of glass fiber with in situ polymerization method. We hope the materials can bring out the performance of the “electron conductor, photon glass”. During the polymerization process, the effects of oxidant concentration and dopant mass fraction on thermoelectric properties of the materials are investigated. The group type of the polymer chain and the morphology of the samples were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), respectively. The maximal Seebeck coefficient (S) and electric conductivity (σ) of the pristine sample are 32 μVK-1 and 169 Sm-1, respectively. After further post-processing with methanol, the thermoelectric properties of materials were improved, and the maximum value of S and σ increased greatly to 48.5 μVK-1 and 3184 Sm-1, respectively. The maximal power factor (PF) of materials also increased from 0.12 μWm-1 K-2 to 6.74 μWm-1 K-2. Moreover, we have proposed a preliminary explanation on the carrier transport mechanism.

Room-temperature and atmospheric-pressure hydrogenation of lignin-derived phenol to KA oil by Pt/NiO@MOFs

Hydrogenation of lignin-derived phenol to KA oil(the mixture of cyclohexanone(K)and cyclohexanol(A))is attractive yet challenging in the sustainable upgrading of biomass derivatives under mild conditions.Traditional supported metal catalysts have been widely studied but the active components on supports often exhibit low recyclability due to their instability under experimental conditions.Here we show fabricating ultrasmall Pt/NiO in the pores of chromium terephthalate MIL-101 as catalysts for hydrogenation of phenol.Impressively,Pt/NiO@MIL-101 achieves catalytic phenol hydrogenation to KA oils of tunable K/A ratios and good reusability under room temperature and atmospheric hydrogen pressure,superior to contrast Pt@MIL-101 and Pt/NiO samples.Such excellent performance mainly originates from the effective adsorption and activation of phenol by coordinatively unsaturated Cr sites and H2 activation on ultrasmall Pt/NiO as well as its effective spillover to the adsorbed phenol over Cr sites for hydrogenation reaction.Substantially,such catalyst also displays the excellent performances for hydrogenation of phenol’s derivatives under mild conditions.

Photodetecting and light-emitting devices based on two-dimensional materials

Two-dimensional （2D） materials, e.g., graphene, transition metal dichalcogenides （TMDs）, and black phosphorus （BP）, have demonstrated fascinating electrical and optical characteristics and exhibited great potential in optoelectronic applications. High-performance and multifunctional devices were achieved by employing diverse designs, such as hybrid systems with nanostructured materials, bulk semiconductors and organics, forming 2D heterostructures. In this review, we mainly discuss the recent progress of 2D materials in high-responsive photodetectors, light-emitting devices and single photon emitters. Hybrid systems and van der Waals heterostructure-based devices are emphasized, which exhibit great potential in state-of-the-art applications.

Solar-heating boosted catalytic reduction of CO_(2） under full-solar spectrum

Catalytic converting CO2 into fuels with the help of solar energy is regarded as‘dream reaction’,as both energy crisis and environmental issue can be mitigated simultaneously.However,it is still suffering from low efficiency due to narrow solar-spectrum utilization and sluggish heterogeneous reaction kinetics.In this work,we demonstrate that catalytic reduction of CO2 can be achieved over Au nanoparticles(NPs)deposited rutile under full solar-spectrum irradiation,boosted by solar-heating effect.We found that UV and visible light can initiate the reaction,and the heat from IR light and local surface-plasmon resonance relaxation of Au NPs can boost the reaction kinetically.The apparent activation energy is determined experimentally and is used to explain the superior catalytic activity of Au/rutile to rutile in a kinetic way.We also find the photo-thermal synergy in the Au/rutile system.We envision that this work may facilitate understanding the kinetics of CO2 reduction and developing feasible catalytic systems with full solar spectrum utilization for practical artificial photosynthesis.

Combining chlorination and sulfuration strategies for high-performance all-small-molecule organic solar cells

Three small-molecule donors based on dithieno [2,3-d:2’,3 ’-d’]-benzo[1,2-b:4,5-b’] dithiophene(DTBDT)unit were designed and synthesized by side chain regulation with chlorinated or/and sulfurated substitutions(namely ZR1,ZR1-Cl,and ZR1-S-Cl respectively),along with a crystalline non-fullerene acceptor IDIC-4 Cl with a chlorinated 1,1-dicyanomethylene-3-indanone(IC) end group.Energy levels,molar extinction coefficients and crystallinities of three donor molecules can be effectively altered by combining chlorination and sulfuration strategies.Especially,the ZR1-S-Cl exhibited the best absorption ability,lowest higher occupied molecular orbital(HOMO) energy level and highest crystallinity among three donors,resulting in the corresponding all-small-molecule organic solar cells to produce a high power conversion efficiency(PCE) of 12.05% with IDIC-4 Cl as an acceptor.

Enhanced Roles of Carbon Architectures in High-Performance Lithium-Ion Batteries

Lithium?ion batteries(LIBs), which are high?energy?density and low?safety?risk secondary batteries, are underpinned to the rise in electrochemical energy storage devices that satisfy the urgent demands of the global energy storage market. With the aim of achiev?ing high energy density and fast?charging performance, the exploitation of simple and low?cost approaches for the production of high capacity, high density, high mass loading, and kinetically ion?accessible electrodes that maximize charge storage and transport in LIBs, is a critical need. Toward the construction of high?performance electrodes, carbons are promisingly used in the enhanced roles of active materials, electrochemi?cal reaction frameworks for high?capacity noncarbons, and lightweight current collectors. Here, we review recent advances in the carbon engi?neering of electrodes for excellent electrochemical performance and structural stability, which is enabled by assembled carbon architectures that guarantee su cient charge delivery and volume fluctuation bu ering inside the electrode during cycling. Some specific feasible assem?bly methods, synergism between structural design components of carbon assemblies, and electrochemical performance enhancement are highlighted. The precise design of carbon cages by the assembly of graphene units is potentially useful for the controlled preparation of high?capacity carbon?caged noncarbon anodes with volumetric capacities over 2100 mAh cm^(-3). Finally, insights are given on the prospects and challenges for designing carbon architectures for practical LIBs that simultaneously provide high energy densities(both gravimetric and volumetric) and high rate performance.

Large magnetic moment at sheared ends of single-walled carbon nanotubes

In this work we report that after single-walled carbon nanotubes(SWNTs) are sheared with a pair of titanium scissors,the magnetization becomes larger than that of the corresponding pristine ones. The magnetization increases proportionally with the number of SWNTs with sheared ends, suggesting that there exist magnetic moments at the sheared ends of SWNTs.By using the coefficient of this linear relation, the average magnetic moment is estimated to be 41.5 ± 9.8 μB(Bohr magneton) per carbon atom in the edge state at temperature of 300.0 K, suggesting that ultrahigh magnetic fields can be produced. The dangling sigma and pi bonds of the carbon atoms at sheared ends play important roles in determining the unexpectedly high magnetic moments, which may have great potential applications.

Gradually modulating the three parts of D-π-A type polymers for high-performance organic solar cells

Organic solar cells(OSCs)have received great attention for the prominent advantage of low-cost,light-weight and potential for fabricating flexible and semi-transparent device via roll-to-roll printing toward making better use of inexhaustible renewable clean energy during the past years[1-4].

Influence of anions on the adsorption of uranyl on hydroxylated α-SiO_2(001):A first-principles study

The adsorption of uranyl on hydroxylated α-SiO_2(001) in the presence of a series of anionic ligands, i.e. OH^-, CO_3^(2-), NO_3^-, H_2PO_4^-, HPO_4^(2-),CH_3COO^-(Ac^-), C_6H_5COO^-(PhCO_2^-), C_6H_5O^-(PhO^-), was studied by the periodic density functional theory(DFT) implemented in the Vienna ab initio simulation package(VASP). For the ligands other than OH^-and PhO^-, only the bidentate coordination modes to the uranyl were considered. The excess charge effect of a charged system was first evaluated by constructing models with net charge as is or neutralized by creating defect at the bottom of silica, and the results show that a neutralized model, even with defects, is more realistic than the charged ones.All uranyl species prefer to bind with the deprotonated site(—O^-) rather than the protonated one(—O_H), which suggests that the increase of pH,which leads to the deprotonation of the surface, may enhance the uranyl adsorption. On the other hand, the anionic ligands, which are formed at higher pH, have negative effects. The weaker acidic ligands, such as H_2CO_3, H_3PO_4 and H_2O, whose speciation in solutions is sensitive to the fluctuation of pH, have more complex effect on the uranyl adsorption than strong acids or bases. Humic substances may coordinate with uranyl through carboxyl and phenolic groups, with the carboxyl group bound stronger. The ternary complexes with one bidentate(or monodentate)anion and one(or two) H20 as ligands, which leads to the uranyl penta-coordinated in its equatorial plane, are more favorable than other configurations when bound to the same anionic ligand. Both the charged nature and the coordination behavior of an anionic ligand are relevant to its ability to influence the adsorption of uranyl on the mineral surface. In addition, the uranyl species adsorbed at the surface functionalized by anionic ligands were also addressed, and the functionalized surfaces have weaker interaction with hydrated uranyl dication.

Nanotechnology and Nanomedicine: A Promising Avenue for Lung Cancer Diagnosis and Therapy

Lung cancer is a leading cause of cancer-related death worldwide,with a very poor overall five-year survival rate.The intrinsic limitations associated with the conventional diagnosis and therapeutic strategies used for lung cancer have motivated the development of nanotechnology and nanomedicine approaches,in order to improve early diagnosis rate and develop more effective and safer therapeutic options for lung cancer.Cancer nanomedicines aim to individualize drug delivery,diagnosis,and therapy by tailoring them to each patient’s unique physiology and pathological features—on both the genomic and proteomic levels—and have attracted widespread attention in this field.Despite the successful application of nanomedicine techniques in lung cancer research,the clinical translation of nanomedicine approaches remains challenging due to the limited understanding of the interactions that occur between nanotechnology and biology,and the challenges posed by the toxicology,pharmacology,immunology,and largescale manufacturing of nanoparticles.In this review,we highlight the progress and opportunities associated with nanomedicine use for lung cancer treatment and discuss the prospects of this field,together with the challenges associated with clinical translation.

Trimetallic nanostructures and their applications in electrocatalytic energy conversions

The advancement and growth of nanotechnology lead to realizing new and novel multi-metallic nanostructures with well-defined sizes and morphology,resulting in an improvement in their performance in various catalytic applications.The trimetallic nanostructured materials are synthesized and designed in different architectures for energy conversion electrocatalysis.The as-synthesized trimetallic nanostructures have found unique physiochemical properties due to the synergistic combination of the three different metals in their structures.A vast array of approaches such as hydrothermal,solvothermal,seedgrowth,galvanic replacement reaction,biological,and other methods are employed to synthesize the trimetallic nanostructures.Noteworthy,the trimetallic nanostructures showed better performance and durability in the electrocatalytic fuel cells.In the present review,we provide a comprehensive overview of the recent strategies employed for synthesizing trimetallic nanostructures and their energy-related applications.With a particular focus on hydrogen evolution,alcohol oxidations,oxygen evolution,and others,we highlight the latest achievements in the field.

Tuning the optoelectronic properties of vinylene linked perylenediimide dimer by ring annulation at the inside or outside bay positions for fullerene-free organic solar cells

Among various perylenediimide(PDI)-based small molecular non-fullerene acceptors(NFAs),PDI dimer can effectively avoid the excessive aggregation of single PDI and improve the photovoltaic performance.However,the twist of perylene core in PDI dimer will destroy the effective conjugation.Thus,ring annulation of PDI dimer is a feasible method to balance the film quality and electron transport,but the systematic study has attracted few attentions.Herein,we choose a simple vinylene linked PDI dimer,V-PDI2,and then conduct further studies on the structure-property-performance relationship of four kinds of derived fused-PDI dimers,namely V-TDI2,V-FDI2,V-PDIS2 and V-PDISe2 respectively.The former two are incorporated thianaphthene and benzofuran at the inside bay positions,and the latter two are fused thiophene and selenophene at the outside bay positions,respectively.Theoretical calculations reveal the inside-and outside-fused structures largely affect the skeleton configuration,the former two tend to be planar structure and the latter two maintain the distorted backbone.The photovoltaic characterizations show that the inside-fused PDI dimers offer high open circuit voltage(VOC),while the outside-fused PDI dimers afford large short-circuit current density(JSC).This variation tendency results from the reasonably tunable energy levels,light absorption,molecular crystallinity and film morphology.As a result,PBDB-T:V-PDISe2 device exhibits the highest power conversion efficiency(PCE)of 6.51%,and PBDB-T:VFDI2 device realizes the highest VOC of 1.00 V.This contribution indicates that annulation of PDI dimers in outside or inside bay regions is a feasible method to modulate the properties of PDI-based non-fullerene acceptors.

Preface to Special Issue on Nanoscience and Catalysis

Over the past decade, to meet the ever increased demand on high‐performance catalysts with excellent activity, selectivity and stability, the nanocatalysts and catalysis have been rigorously explored, resulting in a noticeable progress in new paradigm of nanoscience and nanotechnology for catalysis. Differing remarkably from conventional bulk catalysts, size shrinkage of active components to nanometer scale gives a rise to significantly increased catalytic activity, owing to the high surface‐to‐volume ratio of small particles as well as a large fraction of active atoms with dangling bonds exposed surfaces. In addition, other unique properties of nanomaterials such as surface‐ and strain‐driven lattice distortion, variation in electronic state density and oxidation‐induced charge redistribution could also benefit the catalytic performance.

Development and application of blade-coating technique in organic solar cells

Due to the characteristics of lower material waste,higher crystallinity,roll-to-roll compatibility,and high-throughput continuous processing,blade-coating has been widely applied in the preparation of large-area organic solar cells.In this paper,the technique of blade-coating is introduced,including the effects of blading speed,substrate temperature,and other technological innovations during the process of blade-coating.Besides,the recent progress of blade-coating in organic solar cells is summarized and the active layer prepared by a blade-coating method is introduced in detail,including materials,processing methods,solvents,and additives.The interface layer and electrodes prepared by the blade-coating method are also discussed.Finally,some perspectives on the blade-coating method are proposed.In the foreseeable future,blade-coating will become the core of batch production of large-area organic solar cells,so as to make organic solar cells more competitive.

Design and optical performance investigation of all-sprayable ultrablack coating

Although ultrablack surfaces are urgently needed in wide applications owing to their extremely low reflectance over a broadband wavelength,obtaining simultaneously the ultrablackness and mechanical robustness by simple process technique is still a great challenge.Herein,by decoupling different light extinction effects to different layers of coating,we design an ultrablack coating that is all-sprayable in whole process.This coating presents low reflectance over visible–mid-infrared(VIS–MIR)wavelength(av.R≈1%in VIS),low multi-angle scattering(bidirectional reflection distribution function(BRDF)=10-2–10-3 sr-1),together with good substrate adhesion grade and self-cleaning ability,which are superior to most reported sprayable ultrablack surfaces.The light extinction effects of each layer are discussed.This method is also applicable in other material systems.