查看更多>>摘要：Superhydrophilic surfaces have been applied for supercapacitor;however,during energy storage reaction,how the wettability affects the process of electrochemical reaction specifically is still unclear.Herein,we demon-strate superhydrophilic surface for promotion of electro-chemical reactions by liquid affinity and further explain the mechanism,where the transition of the wettability state caused by the change in surface free energy is the main reason for the obvious increase in specific capacitance.Through citric acid assistance strategy,an intrinsically hydrophobic Ni(OH)2 thick nanosheets(HNHTNs,16 nm)can be transitioned into superhydrophilic Ni(OH)2 ultrathin nanosheets(SNHUNs,6.8 nm),where the water contact angle was 0°and the surface free energy increased from 8.6 to 65.8 mN·m-1,implying superhydrophilicity.Compared with HNHTNs,the specific capacitance of SNHUNs is doubled:from 1230 F·g-1(HNHTNs)to 2350 F·g-1(2 A·g-1)and,even at 20 A·g-1,from 833 F·g-1(HNHTNs)to 1670 F·g-1.The asymmetric capacitors assembled by SNHUNs and activated carbon show 52.44 Wh·kg-1 at 160 W·kg-1 and excellent stability with～90％retention after 5000 cycles(～80％retention after 9500 cycles).The promotion of electrochemical performances is ascribed to the change of surface wettability caused by surface free energy,which greatly increase affinity of electrode to the surrounding liquid environment to reduce the interface resistance and optimize the electron transport path.
查看更多>>摘要：The balancing of the electrochemical perfor-mance,mechanical stability,and processing technology for applying supercapacitors to flexible and wearable elec-tronics continues to encounter severe challenges.Herein,we prepare Ni-Co-Mn hydroxide electrodes with a three-dimensional multichannel structure via a simple hydrothermal method.These are constructed using verti-cally contiguous nanosheets with a uniform thickness and rough surface.The electrodes can provide numerous elec-troactive sites and accelerate the transmission of electrolyte ions.The relationship between the structure and electro-chemical performances is verified by experiments and theoretical calculations.Two-dimensional(2D)planar and one-dimensional(1D)fiber electrodes are prepared using a flexible carbon cloth(CC)and carbon fiber(CF),respec-tively,as substrates.The assembled quasi-solid-state flex-ible asymmetric supercapacitor(FASC)with a two-dimensional sandwich structure using NiCoMn-OH/CC as the electrode achieves a remarkable energy density of 73.8 Wh·kg-1 at a power density of 1.03 kW·kg-1.The quasi-solid-state FASC with a 1D linear structure using NiCoMn-OH/CF as the electrode also attains a high energy density(12.9 Wh·kg-1 at a power density of 0.75 W·kg-1).Moreover,the electrochemical perfor-mances of the NiCoMn/CC//AC/CC and NiCoMn/CF//AC/CF FASCs are not disturbed at different bending angles(0°,45°,90°,135° and 180°).This indicates the superior flexibility of the devices.We also assemble a self-powered energy-harvesting storage system by integrating FASCs and commercial solar cells to verify its practicability.It displays sustainable development potential for energy storage.
查看更多>>摘要：Soft electrochemical actuators that can generate mechanical motions in response to electrical stimuli can be used as artificial muscles in microscale robots.The elec-trode materials are the key component of the electro-chemical actuator because they limit the ion diffusion and accumulation processes and thus affect the deformation in fast response-time and potential engineering applications.Low-dimensional materials,such as one-dimensional(1D)CNT and two-dimensional(2D)vertically stood WS2,are great electrode due to their good electrochemical stability and high surface-to-volume ratios,but show limited performances when being used on their own in the actua-tors because of low reconstruction or low conductivity.A combination of 1D CNT and 2D WS2 could form a heterojunction with both high electrochemical activity and great mechanical stability.Herein,by depositing highly disordered graphene nanosheets(HDGNs)on CNT films and then WS2 on the formed low-dimensional nanocarbon film,a hybrid WS2/HDGN/CNT film was synthesized through a multistep CVD method.Vertically grown WS2 nanosheets were achieved by taking advantage of HDGNs which limits CNTs sliding.So,the volume expansion caused by the transition from WO3 to WS2 can force the vertical growth of WS2.This hybrid film shows excellent electrochemical properties,such as high specific capaci-tance and high rate performance.Soft actuators based on the WS2/HDGN/CNT films show good actuating perfor-mance,including stability and reconfigurability.
查看更多>>摘要：The underwater X-ray imaging technology development is significant to subaqueous target recon-naissance/detection/identification,subfluvial archaeology,submerged resource exploration,etc.As the core of X-ray imaging detection,the scintillator has been plagued by inherent moisture absorption and decomposition,and strict requirements for seamless packaging and waterproofing.Here,we designed a manganese-doped two-dimensional(2D)perovskite scintillator modified by hydrophobic long-chain organic amine through the combination of component and doping engineering.The modified per-ovskites show high water repellency that can be used as an underwater X-ray scintillator.X-ray images of aquatic organisms or other objects with a high spatial resolution of 10 lp·mm-1 at a big view field(32 mm × 32 mm)were obtained by scintillation screen.This hydrophobic per-ovskite scintillator based on molecular design is of great promise in underwater X-ray nondestructive testing tech-nology development.
查看更多>>摘要：Direct methanol fuel cell technology recently becomes the focus of both academic and engineering cir-cles,which stimulates the exploitation and utilization of advanced electrode catalysts with high activity and long lifespan.Herein,we demonstrate a robust bottom-up approach to the spatial construction of three-dimensional(3D)spinel manganese-cobalt oxide-modified N-doped graphene nanoarchitectures decorated with ultrasmall Pt nanoparticles(Pt/MnCo2O4-NG)via a controllable self-assembly process.The incorporation of MnCo2O4 nanocrystals provides abundant hydroxyl sources to pro-mote the oxidative removal of CO-like byproducts on Pt sites,while the existence of 3D porous N-doped graphene networks facilitates the transportation of both ions and electrons in the hybrid system,thus giving rise to remarkable synergetic coupling effects during the methanol oxidation process.Consequently,the optimized Pt/MnCo2O4-NG nanoarchitecture expresses exceptional electrocatalytic properties with a large electrochemically active surface area of 99.5 m2·g-1,a high mass activity of 1508.3 mA·mg-1,strong toxicity resistance and reliable long-term durability,which have obvious competitive advantages over those of conventional Pt/carbon black,Pt/carbon nanotube,Pt/graphene,and Pt/N-doped graphene catalysts with the same Pt usage.
查看更多>>摘要：Hydrogen acquisition from solar energy is an effective way to address energy crisis,which makes the development of efficient photocatalysts become the main direction of scientific research.Herein,cobalt phthalocya-nine/oxygen-doped g-C3N4(CoPc/OCN)S-scheme hetero-junction photocatalyst was designed by coupling multi-step calcination with solvothermal method for enhanced pho-tothermal-assisted photocatalytic H2 evolution.The multi-step calcined g-C3N4 is easier for O-doping formation,and the ethanol solvothermal strategy is utilized to enhance the dispersion of CoPc on OCN nanosheet surface and forms sufficient S-scheme heterojunction through H-bonds.In addition,the active sites and excellent photothermal properties of CoPc itself further improve the integrated photocatalytic activity of CoPc/OCN S-scheme hetero-junction.The optimal photocatalytic hydrogen evolution rate of CoPc/OCN S-scheme heterojunction photocatalyst reached 9.56 mmol·g-1·h-1,which is 2.69 and 1.23 times higher than that of CN and OCN,respectively.This work provides a valuable design idea and scheme for enhancing the multi-factor co-assisted photocatalytic H2 evolution performance.
查看更多>>摘要：Efficient capture,safe storage and release of tri-tium from the international thermonuclear experimental reactor(ITER)reaction exhaust gas is a perplexing problem,and the development of an efficient tritium-getter material with ultra-low hydrogenation equilibrium pressure is con-sidered as a reliable way.In this work,Zr2Co alloy was selected as a tritium-getter material and prepared through induction levitation melting.Fundamental performance test results show that Zr2Co exhibits an ultra-low hydrogenation equilibrium pressure of 3.22 × 10-6 Pa at 25 ℃ and excellent hydriding kinetics under a low hydrogen pressure of 0.005 MPa.Interestingly,unique phase transition behaviors were presented in Zr2Co-H system.Specifically,Zr2CoH5 formed by Zr2Co hydrogenated at room tempera-ture is initially decomposed into ZrH2 and ZrCoH3 at 200 ℃.With the temperature increasing to 350 ℃,ZrCoH3 is dehydrogenated to ZrCo,and then ZrCo further reacts with ZrH2 at 650 ℃ to reform Zr2Co and hydrogen.Among the staged phase transition pathways during dehydrogenation,the decomposition of Zr2CoH5 occurs preferentially,which is well accordance with both the smallest reaction energy barrier and the maximum reaction spontaneity that are determined respectively from kinetics activation energy and thermodynamics Gibbs free energy.Furthermore,first principles calculation results indicate that the stronger binding of hydrogen in interstitial environments of ZrCoH3 and ZrH2 triggers the hydrogen-stabilized phase transfor-mation of Zr2CoH5.The unique phase transition mecha-nisms in Zr2Co-H system can shed light on the further exploration and regulation of analogous staged phase tran-sition of hydrogen storage materials.
查看更多>>摘要：Noble metal surfaces with intrinsic chirality serve as an ideal candidate for investigating enantioselec-tive chemistry due to their superior chemical durability and high catalytic activity.Recently,significant advance has been made in synthesizing metal nanocrystals with intrinsic chirality.Nonetheless,the majority reports are limited to gold.Herein,through a heteroepitaxial growth strategy,the synthesis of metal nanocrystals with intrinsic chirality to palladium was extended for the first time and their appli-cation in enantioselective recognition was demonstrated.The heteroepitaxial growth strategy allows for transferring the chirality of homochiral Au nanocrystals to Au@Pd core-shell nanocrystals.By employing the chiral Au@Pd nanocrystals as enantiomeric recognizing elements,a series of electrochemical sensors for chiral discrimination were developed.Under optimal conditions,the peak potential between D-dihydroxyphenylalanine(D-DOPA)and L-di-hydroxyphenylalanine(L-DOPA)is about 80 mV,and the peak current of D-DOPA is 2 times as much as that of L-DOPA,which enables the determination of the enan-tiomeric excess(EE,％)of L-DOPA.Overall,this report not only introduces a heteroepitaxial growth strategy to synthesize metal nanocrystals with intrinsic chirality,but also demonstrates the superior capability of integrating intrinsic chirality and catalytic properties into metal nanocrystals for chiral recognition.
查看更多>>摘要：The design and synthesis of catalysts for the oxidation desulfurization and production of hydrogen are extremely important for solving environmental pollution and energy shortage.Herein,a novel bifunctional[α-Mo8O26]4-/[β-Mo8O26]4--based Cu-viologen complex H4[Cu2ICl2(Hbcbpy)4][α-Mo8O26][β-Mo8O26]·H2O(BHU-2,Hbcbpy=1-(4-carboxybenzyl)-4,4'-bipyridinium)was synthesized and characterized by single-crystal X-ray diffraction(XRD),infrared radiation spectra,powder X-ray diffraction(PXRD)and X-ray photoelectron spec-troscopy(XPS)spectra.The structural characteristic of BHU-2 is the presence of two types of octamolybdate clusters[α-Mo8O26]4-/[β-Mo8O26]4-and a new binu-clear CuI-Hbcbpy complex linked by Cl-bridges[Cu2ICl2(Hbcbpy)4]4+.BHU-2 as a heterogeneous catalyst exhibits excellent activities to the oxidation desulfurization and photocatalytic hydrogen production.At room temper-ature,BHU-2 can catalyze 96％conversion of methyl phenyl sulfide with 98％selectivity,and the process obeys the pseudo-first-order reaction kinetic with the half-life of 9.6 min.The notorious 2-chloroethyl ethyl sulfide can achieve 99％conversion with 98％selectivity within only 1 min at the presence of BHU-2,and the turnover fre-quency(TOF)is up to 7400 h-1.BHU-2 also exhibits high catalytic activity for the oxidation of other aromatic and aliphatic thioethers within short time at room temperature.Furthermore,BHU-2 shows a high catalytic activity for visible-light-driven hydrogen evolution with an H2 evolu-tion rate of 1677.85 μmol·g-1·h-1 within 10 h.Moreover,the catalytic activities do not decrease evidently after three cycles,revealing the prominent structural stability and recyclability.
查看更多>>摘要：Metal oxide semiconductors(MOSs)are ideal sensing materials for detecting volatile organic compounds due to their low cost,diversity,high stability,and ease of production.However,it remains a grand challenge to develop the MOSs-based gas sensors for sensing iso-propanol with desired performance via a simple,effective,and controllable method.Herein,we reported the prepa-ration of the Al-doped ZnO(AZO)/WO3 heterostructure films by directly depositing the AZO coating onto the WO3 coating using a strategy of magnetron sputtering.The AZO/WO3 heterostructure films were constructed by numbers of irregular nanoparticles that were intercon-nected with each other.The AZO/WO3 heterostructure films-based gas sensors exhibited excellent isopropanol-sensing performance with high response,promising selec-tivity,low detection limit,fast response rate,wide detec-tion range,and ideal reproducibility.The promising isopropanol-sensing performance of the AZO/WO3 heterostructure films arises mainly from their high unifor-mity,unique microstructures with high surface roughness,and the construction of the heterostructure between the AZO and WO3 coatings.This work provides a versatile approach to prepare the MOSs-based heterostructure films for assembling the gas sensors.
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