Octahedral metal phase molybdenum disulfide (1T-MoS2) shows excellent capacitive behaviour by storing charge via double layers over individual two-dimensional (2D) layers and through Faradaic reactions on the Mo centre because of its multiple oxidation states. In this study, we fabricate a free-standing film based on large-scale 1T-MoS2 nanosheets and use it as an electrode for a flexible supercapacitor without any additives. The resulting free-standing electrodes have a layered structure, hydrophilicity and high electrical conductivity, which are beneficial for electrolyte accessibility and fast ions transport. The specific volumetric capacitance of this pure 1T-MoS2-based electrode is up to 407.1 F . cm(-3) (the corresponding mass and area capacitance were 26.1 F . g(-1) and 184.8 mF . cm(-2), respectively). The all-solid-state 1T-MoS2 based supercapacitor shows extended stability (92.8% retention after 12, 000 cycles), high flexibility (only 12% drop after bending 180 degrees for 100 cycles) and bending cycling stability (86.2% retention after in-situ bending 1500 times).
In this work, high-crystalline Ga2O3 nanorods with improved photoelectrochemical properties were fabricated on Ti substrates by a facile electrodeposition. The photocurrent density of oval-like Ga2O3 nanorods is 122.4 uA cm(-2) at 0.6 V vs. Ag/AgCl, which is much higher than that of rectangular Ga2O3 nanorods (69 uA cm(-2)). This enhancement in performance might be ascribed to the decreased bandgap energy, which greatly promotes its oxidation ability of photogenerated hole.
Li4Ti5O12-TiO2 (LTO-TO) composite is coated on carbon foam (CF) for anode of lithium ion capacitors (LICs). The resulting CF@LTO-TO electrodes with varied mass loadings of LTO-TO exhibit much improved rate performance compared to pristine LTO electrode. Specifically, asymmetric LICs based on activated carbon cathode and CF@LTO-TO anode (AC//CF@LTO-TO) with 25 wt% of LTO-TO delivers a specific capacity of 65 mAh g(-1) at 300 C. In addition, the self-discharge rates of the LICs are evaluated. It is found that AC//CF@LTO-TO LIC with 45 wt% of LTO-TO shows much reduced self-discharge rate (open circuit voltage drops from 2.5 to 1.1 V in 144 hours) relative to AC//CF@LTO-TO with different LTO-TO mass loadings. The results of this study suggest that the introduction of TO in LTO anode can affect both the rate performance and the self-discharge behavior, which may be due to the fast faradaic reaction kinetic of TO and the rich LTO-TO grain boundary interfaces.
Upconversion luminescent-magnetic [Y2O3:Yb3+, Er3+/polyacrylonitrile (PAN)]//[CoFe2O4/PAN] alloplastic nanofiber yarns (ANYs) are successfully prepared by a novel conjugative electrospinning. The ANYs consist of two different kinds of nanofibers, respectively called as [CoFe2O4/PAN] magnetic nanofibers and [Y2O3:Yb3+, Er3+/PAN] upconversion luminescent nanofibers, and the two kinds of nanofibers are combined together and twisted to form ANYs. Pumped by 980-nm laser, the ANYs exhibit excellent upconversion luminescence (UCL) and orange-red fluorescence. ANYs demonstrate tailored saturation magnetization by modulating CoFe2O4 nanoparticles (NPs) content. The influence mechanism of magnetic CoFe2O4 NPs on the UCL of ANYs is detailedly explored. The relationship between mechanical properties and twist for ANYs is explored through the tensile test. Compared with the counterpart coessential nanofiber yarns (CNYs), ANYs exhibit about 10 times stronger UCL intensity owing to the complete separation of the upconversion luminescent substance from the magnetic substance and thereby great reduction of impact of the magnetic substance on the upconversion luminescent substance. Thus, concurrent enhancive upconversion luminescence (UCL) and tunable magnetism of the ANYs are successfully achieved. The detailed formation mechanism of ANYs is advanced and a novel fabrication technique of yarns is established and can be popularized to prepare other bi- and multi-functional nanofibrous yarns.
As a carbon-neutral alternative technology to the Haber-Bosch process, electrochemical N(2)reduction enables eco-friendly NH(3)synthesis under ambient conditions but requires electrocatalysts to drive the N(2)reduction reaction (NRR). Here, P doping is proposed as a valid strategy to greatly increase the NRR activity of the V2O3/C shuttle-like nanostructure. In 0.1 M Na2SO4, the NH(3)yield of original V2O3/C is 12.6 mu g h(-1) mg(cat.)(-1)and a Faraday efficiency (FE) of 6.06% at -0.45 V and -0.25 V vs. reversible hydrogen electrode (RHE), respectively. P-doped V2O3/C (P-V2O3/C), with a mass ratio of P of 6.05%, is capable of achieving a large NH(3)yield of 22.4 mu g h(-1) mg(cat.)(-1)at -0.35 V vs. RHE, and a high FE of 13.78% at -0.25 V vs. RHE. It also shows high electrochemical durability and outstanding selectivity for NH(3)formation. Combined with density functional theory calculations, the catalytic mechanism was further explored.
The development of cost-effective electrocatalysts is vital for promoting the practical application of hydrazine as a viable energy carrier. However, the catalytic performance of the single-atom Cu catalyst has not been evaluated with regard to the hydrazine oxidation reaction (HzOR). Herein, single Cu atoms anchored on the surface of the P-doped C(3)N(4)substrate (Cu-SA/PCN) have been synthesized using a simple method that involved pyrolysis and phosphorization. The as-obtained Cu-SA/PCN catalyst is observed to demonstrate a suitable efficiency for the electrocatalytic hydrazine oxidation at the anode in an alkaline aqueous solution. Remarkably, the catalyst exhibits an excellent electrolytic activity and strong durability for 30 h. Further, it displays a current density of 100 mA cm(-2)at a low applied potential of 0.336 V versus the reversible hydrogen electrode. Therefore, this study provides a strategy to manufacture single atom catalysts for an efficient HzOR in alkaline media.
Controllable self-propelled droplet robots show great potential to be used as carriers, sensors and actuators in biological medicine and oil exploration. Current research mainly focuses on studying oil droplet robots floating in water phase which has limited application. Different from the previous robots, a light-driven self-propelled water-phase droplet micro robot, which is doped with Fe(2)O(3)nanoparticles, moving in oil solvent is proposed. Unlike light-driven oil droplets, the water drop robot is constantly diving towards the light source like a submarine moving in oil environment under blue laser irradiation. Numerical simulations are performed to investigate the water/oil interface behavior and the motion mechanism of micro robots. It is found that a photocatalytic Fenton reaction occurs on the irradiated Fe(2)O(3)nanoparticles of water droplet robot, which causes uneven ion concentration to change the interfacial tension distribution of the water drop generating Marangoni flow. In addition to phototaxis behavior, further experiments confirmed that multiple water droplet micro robots show collective behavior under the control of surface light source. The proposed water droplet micro robot provides new possibilities for the development of targeted drug delivery, oil-water separation as well as oil pollution treatment.
Semiconductor nanocrystals showing surface plasmonic absorption features can be used as prospective substitutes for noble metallic nanoparticles. Herein, a creative one-pot hydrothermal route without template is used to synthesize plasmonic oxygen deficiency molybdenum oxide (MoO3-x) nanoparticles. The morphologies of as-prepared MoO(3-x)nanomaterials arranged from amorphous to crystalline with the reaction temperature varied from 160 degrees C, 180 degrees C to 200 degrees C, namely MoO(3-x)quantum dots (QDs), MoO(3-x)nanosheets, and MoO(2)nanospheres. Simultaneously, in the near-infrared region (NIR), MoO(3-x)nanomaterials exhibit gradually enhanced localized surface plasmon resonance (LSPR) absorption, of which MoO(2)nanospheres exhibit intense NIR absorption with a photothermal conversion efficiency up to 72.5% under 808 nm NIR laser irradiation. Moreover, the toxicity and cancer therapy efficacy of MoO(2)nanospheres have been systematically assessedin vitroandin vivo, respectively. The results revealed that MoO(2)nanospheres exhibit low toxicity and high therapeutic efficiency, making it an promising and effective photothermal agent in photothermal therapy
Battery-type electrode materials such as NiS applied in Faradaic supercapacitors (FSs) could display poor performance with regard to rate-capability and cycling stability due to the inappropriate texture of the electrodes. Numerous works focussed on tuning the microscopic structure of electrode materials, but neglected the influence of the microscopic structure of current collectors such as nickel foam on the electrochemical performance of FSs. In this work, the performance of NiS is associated with the microscopic structure of nickel foams by decorating the 2D porous nanostructured NiS on a 2D nanoengineered skeleton-surface of nickel foams. It could be inferred from the characterization results that the synergistic effect of both 2D nanostructured NiS and nickel foam significantly promotes the rate-capability and stabilizes the performance of NiS. Asymmetric supercapacitors using the dually nanostructured NiS/nickel foam as positive electrode and AC as negative electrode exhibit both high energy and high power densities.
Lithium-ion battery (LIB) is a dominating power source in the market owing to its high energy density, good cycling stability and environmental benignity. However, technical challenges remain after years' optimization and commercialization, which are detrimental to the expected performance and lifespan of LIBs. For instance, many cathode materials of LIBs suffer from rapid capacity fading and poor high-rate performance, which are ascribed to self-aggregation, dissolution and fast increased charge transfer resistances during cycles. In terms of the anode materials, low coulombic efficiency, electrolyte depletion and safety issues are common. In addition, the liquid electrolyte systems trigger safety concerns because flammable and volatile organic solvents are necessary. Recently, carbon dots (CDs) emerge as a sound material to address those challenges of LIBs, and also present promising applications in bioimaging, fluorescence sensing, photo/electro-catalysis, and electroluminescence. This review will overlook the state-of-the-art advances in the employment of CDs based composites to build cathode/anode materials and electrolytes in LIBs, through tailoring the internal structures and the surface states of electrode materials, and being additives in electrolyte, to improve the performances of the next-generation LIBs. The major challenges and opportunities in front of CDs in LIBs will be outlined and discussed in detail.
In recent years, two-dimensional materials have been widely used in the field of optics due to their unique nonlinear optical properties, broadband saturation absorption and ultrafast recovery time. MXene Ti(3)C(2)T(x)is a kind of emerging two-dimensional materials with large modulation depth, high damage threshold, and excellent electrical conductivity with near zero bandgap structure. However, MXene has seldom been applied in ultrafast photonics, especially the generation of ultrastable soliton molecules. In this paper, MXene is prepared and applied in the erbium-doped fiber laser. The nonlinear optical properties of MXene Ti(3)C(2)T(x)are studied experimentally. The center wavelength, 3-dB bandwidth, fundamental frequency and the pulse duration of the conventional soliton are 1566.1 nm, 1.21 nm, 6.09 MHz and 993 fs, respectively. By adjusting the polarization state and pump power, the soliton molecules can be obtained in the laser cavity. Especially, two kinds of soliton molecules with CW peak and without CW peak are observed, respectively. Experimental results show that MXene saturable absorber (SA) can bear a high pump power. This work demonstrates that MXene Ti(3)C(2)T(x)can be used as an excellent SA. Hence, we believe that this kind of optical material has many applications such as optical communication, optical logic gates and nonlinear devices, etc.
Ligand-Free yolk-shell nanoparticles (LFYSNs) consist of ligand-free core (nanoparticle) enclosed in a hollow nanocavity of a porous shell have been attracted great interest owing to their unique nanoarchitecture features, enchanting physicochemical properties and extensive potential applications. LFYSNs are considered as a unique category of conventional yolk-shell nanoparticles (YSNs). YSNs are usually consist of organic-capped core (nanoparticle) and the presence of capping ligands on the surface of metal core may show deleterious effects in catalytic applications. Here, a comprehensive overview on the recent progress of LFYSNs synthetic strategies and catalytic applications are discussed. The fabrication methods for LFYSNs are mainly focused on a ''ship-in-a-bottle/pre-shell'' approach and sub-divided into three categories, including volume confined, photochemical and seedless/colloidal methods. The catalytic applications of LFYSNs including chemical and photo catalysis, and electrocatalysis are discussed in detail. Moreover, the superlative catalytic activity of LFYSNs is highlighted. Finally, perspectives on future research direction and development of LFYSNs are discussed briefly.
Monolithic electrodes show a great advantage in energy storage devices. Nitrogen/oxygen co-doped carbons sponges (NOCSs) prepared from carbonized melamine foams are directly applied as the supercapacitor electrodes without any additives and binders. The influence of carbonization temperatures from 650 to 950 degrees C on the heteroatom (N and O) content, surface area, graphitization degree, and capacitor performance of carbon sponges are systematically investigated, and it is found that NOCS-850 delivers a better overall capacitive properties for its balanced heteroatom content, surface area, and graphitization degree. It possess specific capacitances of 338 F g(-1)at a scan rate of 1.0 mV s(-1)and 168.3 F g(-1)at a current density of 0.5 A g(-1)in 1.0 M H2SO4. After 5000 cycles of repeated charging/discharging process, the capacitance retention remains 107%. When being assembled into an all-solid-state supercapacitor, the NOCS-850 has a energy density of 5.38 Wh kg(-1)at a power density of 233 W kg(-1). A red light-emitting diode can be successfully lighted by three connected all-solid-state supercapacitors of NOCS-850, illustrating its potential application in energy storage field.
Due to the existence of hypoxic microenvironment, the efficacy of photodynamic therapy (PDT) is frequently weakened. As a result, targeted treatment toward oxygen-rich mitochondria is considered as a promising cancer therapy. Herein, both triphenylphosphine (TPP) and folic acid (FA) are simultaneously grafted onto nanoscale metal-organic frameworks (NMOFs) to realize dual-targeting delivery of the nanoplatforms into cancer cells and their mitochondria via the proposed phosphorylation modification strategy. A large amount of highly efficient photosensitizer of porphyrinic molecules is integrated into the NMOFs with a uniform particle size of about 65 nm. Thanks to the strong Zr-O-P bonding, a dense coverage of phosphonate-conjugating targeting molecules on NMOFs is obtained and each surficial unsaturated Zr-O cluster is adequately occupied. The resultant dual-targeting NMOFs feature high biostability and biocompatibility, as well as improved cellular uptake and mitochondrial accumulation. The PDT efficacy of these dual-targeting NMOFs is significantly improved with a low IC50 of 0.74 mu M upon 10 min light radiation, which is at least four times higher than that of non-targeting counterparts. This phosphorylation strategy would be hopeful for immobilizing a variety of biogenic groups on NMOFs to make them targetable to various specific organelles and to improve the therapy efficacy on related diseases.
Hollow-structured electrode materials have found broad applications in secondary batteries. The built-in cavity of the prepared materials shows favorable features such as structural stability against volumetric deformation, good reservoir for electrolyte, and fast charge transport kinetics, which are highly efficient to improve the electrochemical performance of the electrode materials, particularly their cycling stability and high rate capability. However, the full potential of hollow-structured materials is restrained by their limited synthesis capability, which currently relies on template-based protocols with well-known challenges in both product yield and operational convenience. In this review, the recent progress on different synthetic methodologies for the creation of hollow structures without the use of extra templates is summarized. Starting from solid precursors, focus is laid on the formation mechanisms for the creation of a cavity inside the electrode materials, and subsequently different driving forces such as Ostwald ripening, Kirkendall effect, and selective etching of an inhomogeneous particle are discussed, highlighting the self-templated processes as designable and scalable ones with good control on the key structural characters. Furthermore, the applications of hollow structures in different kinds of battery systems are discussed in terms of building up a clear structure-performance relationship of the electrode materials. Finally, we provide a perspective on the development trends of self-templated construction of hollow structures.