Flexible planar micro supercapacitor diode

Supercapacitor diode is a novel ion device that performs both supercapacitor energy storage and ion diode rectification functions.However,previously reported devices are limited by their large size and complex processes.In this work,we demonstrate a screen-printed micro supercapacitor diode(MCAPode)that based on the insertion of a finger mode with spinel ZnCo_(2)O_(4) as cathode and activated carbon as anode for the first time,and featuring an excellent area specific capacitance(1.21 mF cm^(-2)at 10 mV s^(-1))and high rectification characteristics(rectification ratioⅠof 11.99 at 40 mV s^(-1)).Taking advantage of the ionic gel electrolyte,which provides excellent stability during repeated flexing and at high temperatures.In addition,MCAPode exhibits excellent electrochemical performance and rectification capability in"AND"and"OR"logic gates.These findings provide practical solutions for future expansion of micro supercapacitor diode applications.

Urea electrooxidation-boosted hydrogen production on nitrogen-doped porous carbon nanorod-supported nickel phosphide nanoparticles

Urea electro-oxidation reaction(UEOR)-boosted water electrolysis can supplant the kinetics-restricted oxygen evolution reaction(OER)and provide an energy-saving method of hydrogen generation.However,low UEOR activity and the poisoning issue of the catalyst limit its practical application.Herein,a simple coordination reaction is used to synthesize the dimethylglyoxime-NiⅡcomplex(DMGNiⅡ),which efficiently serves as the initial precursor to synthesize nitrogen-doped carbon nanorodsupported nickel phosphide nanoparticle(Ni_(2)P/N-C)nanocomposites.The density functional theory calculations and electrochemical results reveal that nitrogen doping can weaken the adsorption of hydrogen and the generated CO_(2)resulting in an enhancement of hydrogen evolution reaction(HER)and UEOR activity.In addition,N-doping can also promote the generation of Ni,which can further promote the UEOR and HER performance.Concretely,the overpotential for the HER on Ni_(2)P/N-C-2h nanocomposites is only 201 m V at 10 mA cm,and the onset potential of the UEOR on NiP/NC-2h nanocomposites is only 1.34 V.Additionally,the Ni_(2)P/N-Cnanocomposites also show excellent long-term stability due to the introduction of nitrogen-doped carbon material.Consequently,the symmetric Ni_(2)P/N-C-2h||Ni_(2)P/N-C-2h urea electrolyzer requires 1.41 V of electrolysis voltage for urea electrolysis,which can be applied in energy-saving H_(2) production and environment purification.

Photocatalytic one-step synthesis of Ag nanoparticles without reducing agent and their catalytic redox performance supported on carbon

Synthesis of silver nanoparticles(Ag NPs) with state-of-the-art chemical or photo-reduction methods generally takes several steps and requires both reducing agents and stabilizers to obtain NPs with narrow size distribution.Herein, we report a novel method to synthesize Ag NPs rapidly in one step, achieving typical particle sizes in the range from 5 to 15 nm.The synthesis steps only involve three chemicals without any reducing agent: AgNO3 as precursor, polyvinylpyrrolidone(PVP) as stabilizer, and AgCl as photocatalyst.The Ag NPs were supported on carbon and showed excellent performance in thermal catalytic pnitrophenol reduction and nitrobenzene hydrogenation, and as electrocatalyst for the oxygen reduction reaction.

Dynamic Control of Multiple Optical Patterns of Cholesteric Liquid Crystal Microdroplets by Light-Driven Molecular Motors

The key to high-level encryption and anti-counterfeiting techniques is the storage of multiple levels of distinct information that can be individually and precisely addressed by certain stimuli.This continues to be a formidable challenge as the concealed images or codes must be read with fast response and high resolution without cross-talk to the first layer of information.Here,we report a non-fluorescencebased strategy to establish responsive encryption labels taking advantage of solely tuning multiple optical patterns of cholesteric liquid crystal(CLC)microdroplets doped with light-driven molecular motors.The photo-triggered unidirectional rotation of the motor induced not only changes in the helical twist power value but the opposite helical orientation of the superstructure in CLCs as well,resulting in changes in both the structural color and the selective reflection of circularly polar light.The designed labels,which featured highly selective addressability of dual-level distinct information,good reversibility,and viewing angle-independence,were applied to build devices for daily practical use,demonstrating great potential in anti-counterfeiting technology and provide a versatile platform for enhanced data protection and encryption of authentic information.

Highly efficient nonuniform finite difference method for three-dimensional electrically stimulated liquid crystal photonic devices

Liquid crystal(LC)photonic devices have attracted intensive attention in recent decades,due to the merits of tunability,cost-effectiveness,and high efficiency.However,the precise and efficient simulation of large-scale three-dimensional electrically stimulated LC photonic devices remains challenging and resource consuming.Here we report a straightforward nonuniform finite difference method(NFDM)for efficiently simulating largescale LC photonic devices by employing a spatially nonuniform mesh grid.

A reflective display based on the electro-microfluidic assembly of particles within suppressed water-in-oil droplet array

Reflective displays have stimulated considerable interest because of their friendly readability and low energy consumption.Herein,we develop a reflective display technique via an electro-microfluidic assembly of particles(eMAP)strategy whereby colored particles assemble into annular and planar structures inside a dyed water droplet to create"open"and"closed"states of a display pixel.Water-in-oil droplets are compressed within microwells to form a pixel array.The particles dispersed in droplets are driven by deformation-strengthened dielectrophoretic force to achieve fast and reversible motion and assemble into multiple structures.This eMAP based device can display designed information in three primary colors with≥170°viewing angle,~0.14 s switching time,and bistability with an optimized material system.This proposed technique demonstrates the basis of a high-performance and energy-saving reflective display,and the display speed and color quality could be further improved by structure and material optimization;exhibiting a potential reflective display technology.

Ultrathin Ni(OH)2 layer coupling with graphene for fast electron/ion transport in supercapacitor

Integration of fast electrochemical double-layer capacitance and large pseudocapacitance is a practical way to improve the overall capability of supercapacitor,yet remains challenging.Herein,an effective cyanogel synthetic strategy was demonstrated to prepare ultrathin Ni(OH)2 nanosheets coupling with conductive reduced graphene oxide(rGO)(rGO-Ni(OH)2)at ambient condition.Ultrathin Ni(OH)2 nanosheet with 3–4 layers of edge-sharing octahedral MO6 maximally exposes the active surface of Faradic reaction and promotes the ion diffusion,while the conductive rGO sheet boosts the electron transport during the reaction.Even at 30 A g−1,the optimal sample can deliver a specific capacitance of 1119.52 F g−1,and maintain 82.3%after 2000 cycles,demonstrating much higher electrochemical capability than bare Ni(OH)2 nanosheets.A maximum specific energy of 44.3 W h kg^−1(148.5 W kg^−1)is obtained,when assembled in a two-electrode system rGO-Ni(OH)2//rGO.This study provides an insight into efficient construction of two dimensional hybrid electrodes with high performance for the new-generation energy storage system.

Chemical vapor deposition of amorphous molybdenum sulphide on black phosphorus for photoelectrochemical water splitting

Non-precious metal electrocatalyst molybdenum sulphide(MoS) and black phosphorus(BP) are highly promising catalysts for H_(2) evolution reaction(HER).However,BP is environmentally unstable and the basal planes of crystal MoS_(2) are inactive toward HER.Herein,amorphous molybdenum sulphide(MoSx)directly on BP/BiVO4 film dramatically improves the performance of photoelectrochemical water splitting compared with pure BiVO4.Additionally,we demonstrate that a BP layer,inserted between the MoSx and BiVO4,can enhance the photoelectrochemical performance and improve the stability of the electrodes.Finally,MoS_(x)/B P/BVO electrode shows the excellent current density of 2.1 mA/cm^(2) at the potential of 1.2 V(vs Ag/AgCl),which is twice higher than that of pure BVO electrode.Our novel nanostructure materials will lead to a new class of non-precious metal photocatalysts for hydrogen production.

Generation and control of dynamically tunable circular Pearcey beams with annular spiral-zone phase

Light-field shaping technology plays an important role in optics and nanophotonics. For instance, the spatially structured light field, which exhibits characteristic features in complex phases, light intensity, and polarization, is crucial to understanding new physical phenomena and exploring practical applications. Herein, we propose and demonstrate a new class of tunable circular Pearcey beams(TCPBs) by imposing the annular spiral-zone phase(ASZP). Through experiments, we used a spatial light modulator to generate TCPBs based on their spiral phase distribution, and numerically analyzed the generation and control of the beams with unusual autofocusing and self-rotating dynamics. ASZP is a general term for complex phases composed of the spiral phase,equiphase, and radial phase. TCPB typically exhibits dynamical properties, including abrupt autofocusing, automatic generation of optical bottles, and self-rotation of the beam pattern, during propagation. Besides, the number of generated optical bottles can be modulated by the superposition mode of ASZP and the number of subphases. We found that an inappropriate superposition mode leads to distortion, and we analyzed the underlying mechanism. Potential applications of TCPBs in optical manipulation are also discussed, presenting an exemplary role desired for light-field manipulation.

Liquid crystal-based optical aptasensor for the sensitive and selective detection of Gram-negative bacteria

The sensitive and differential detection of Gram-negative bacteria is essential in food processing,environmental monitoring,and the daily chemical industry.Herein,we propose and validate a liquid crystal(LC)-based aptasensor for the ultrasensitive detection of Escherichia coli(E.coli),a model of Gram-negative bacteria.The nematic liquid crystal of 4-cyano-4’-pentylbiphenyl(5 CB) molecules can be orderly or disorderly arranged at the LC-aqueous interface via different stimuli,causing changes in optical texture due to birefringence.Bright schlieren texture is observed when a mixture solution of aptamer and hexadecyl trimethyl ammonium bromide(CTAB) is dripped onto the segmented LC films on a copper mesh.The specific binding of aptamers with target bacteria biomarkers liberates the CTAB molecules,which then self-assemble at the LC-aqueous interface to induce the vertical alignment of LCs.An optical transition from bright to dark is therefore achieved via the LC molecular orientation and serves as an aptasensor.Given the prominent affinity and specificity of the aptamer,the established sensitive and selective E.coli assay shows an ultralow detection limit of 27 cfu/mL.The prepared aptasensor can also be applied for the sensitive and selective determination of E.coli in fruit juice,soft drink,and cosmetic products,and shows great promise for the on-site detection of Gram-negative bacteria with high sensitivity and specificity for environmental monitoring,food safety assessment,and household chemical inspection.