Robust Dichotomy Solution-Based Model Predictive Control for the Grid-Connected Inverters with Disturbance Observer

This paper proposes a robust dichotomy-based model predictive control(DS-MPC)with a fixed switching frequency for the grid-connected inverter(GCI).The proposed fast dichotomy algorithm can select and deduce the optimal voltage vector dynamically through the space vector plane.Therefore,the proposed DS-MPC strategy could ensure dynamic performance and steady-state performance as well.Also,the current control robustness can be improved through DS-MPC with disturbance observer(DO)based on the extended Kalman filter(EKF).The novelty of this control is that the current control with fast dynamic response can be realized in the weak grid,even if the grid voltages are greatly distorted.Simulation and hardware experiments on the weak grid validate the effectiveness of the proposed DS-MPC with the EKF observer approach.

Nanocrystals:Solution-Based Synthesis and Applications as Nanocatalysts

Nanocrystals are emerging as key materials due to their novel shape-and size-dependent chemical and physical properties that differ drastically from their bulk counterparts.The main challenges in this field remain rationally controlled synthesis and large scale production.This article reviews recent progress in our laboratory related to solution-based synthesis of various nanostructures,including zero-dimensional(0-D)nanocrystals,1-D nanowires and nanorods,hollow structures,and superlattice materials.On the other hand,the essential goal for nanoresearchers is to achieve industrial applications of nanostructured materials.In the past decades,these fascinating materials have been widely used in many promising fields such as nanofabrication,nanodevices,nanobiology,and nanocatalysis.Herein,we focus on their applications as nanocatalysts and try to illustrate the main problems and future directions in this area based on our recent endeavors in catalytic applications of nanocrystals.

Facile Solution-based Synthesis and Optical Properties of Co3O4 Nanoparticles at Low-temperature

Cobalt oxide（C0304） with different morphologies was achieved by a simple solution-based method. Various parallel experiments show that several experimental parameters, such as the concentrations of NaOH and ethylene glyeol（EG）, play important roles in the morphological controlling of C0304 nanoparticles. A lower concen- tration of NaOH favors quasi-spherical product with a uniform size of about 15 nm, whereas a higher concentration of NaOH generally leads to the formation of nanoplates with wide size distribution. In addition, C0304 nanorods were also obtained partially by introducing a certain amount of EG. A possible mechanism was proposed for the selective formation of C0304 with various morphologies. X-Ray diffraction（XRD）, infrared（IR） spectrometry, scanning elec- tron microscopy（SEM）, transmission electron microscopy（TEM） and UV-Vis spectrometry were used to characterize the samples.

Solution-based processing of carbon nitride composite for boosted photocatalytic activities

Graphite-phase polymeric carbon nitride （CN） was reported to be a promising material in photoelectrochemical solar energy conversion. However, its high recombination rate of photogenerated carriers limits its potential applications. In this article, a heterojunction of CN and sulfur-doped CN （CNS） was constructed through a solution-based processing way. Interestingly, it was observed that the photocatalytic hydrogen production of the as-prepared composite was 32.6 times higher than that of bulk carbon nitride and 2.3 times higher than that of the composites by conventional impregnating method. This study opens a new avenue to construct heterojunction of CN for large-scale industrial applications in environmental remediation.

A Preliminary Analysis of Trace-Elemental Signatures in Statoliths of Different Spawning Cohorts for Dosidicus gigas off EEZ Waters of Chile

We applied solution-based ICP-MS method to quantify the trace-elemental signatures in statoliths of jumbo flying squid, Dosidius gigas, which were collected from the waters off northern and central Chile during the scientific surveys carried out by Chinese squid jigging vessels in 2007 and 2008. The age and spawning date of the squid were back-calculated based on daily increments in statoliths. Eight elemental ratios(Sr/Ca, Ba/Ca, Mg/Ca, Mn/Ca, Na/Ca, Fe/Ca, Cu/Ca and Zn/Ca) were analyzed. It was found that Sr is the second most abundant element next to Ca, followed by Na, Fe, Mg, Zn, Cu, Ba and Mn. There was no significant relationship between element/Ca and sea surface temperature(SST) and sea surface salinity(SSS), although weak negative or positive tendency was found. MANOVA analysis showed that multivariate elemental signatures did not differ among the cohorts spawned in spring, autumn and winter, and no significant difference was found between the northern and central sampling locations. Classification results showed that all individuals of each spawned cohorts were correctly classified. This study demonstrates that the elemental signatures in D. gigas statoliths are potentially a useful tool to improve our understanding of its population structure and habitat environment.

Properties of vapor-deposited and solution-processed targets for laser-driven inertial confinement fusion experiments

Targets for low-adiabat direct-drive-implosion experiments on OMEGA must meet rigorous specifications and tight tolerances on the diameter,wall thickness,wall-thickness uniformity,and presence of surface features.Of these,restrictions on the size and number of defects(bumps and depressions)on the surface are the most challenging.The properties of targets that are made using vapor-deposition and solution-based microencapsulation techniques are reviewed.Targets were characterized using confocal microscopy,bright-and dark-field microscopy,atomic force microscopy,electron microscopy,and interferometry.Each technique has merits and limitations,and a combination of these techniques is necessary to adequately characterize a target.The main limitation with the glow-discharge polymerization(GDP)method for making targets is that it produces hundreds of domes with a lateral dimension of 0.7-2 μm.Polishing these targets reduces the size of some but not all domes,but it adds scratches and grooves to the surface.Solution-made polystyrene shells lack the dome features of GDP targets but have hundreds of submicrometer-size voids throughout the wall of the target;a few of these voids can be as large as~12 μm at the surface.

Preparation of Li4TisO12 Microspheres with a Pure Cr2O3 Coating Layer and its Effect for Lithium Storage

The pure Cr2O3 coated Li4Ti5O12 microspheres were prepared by a facile and cheap solution- based method with basic chromium（III） nitrate solution （pH=ll.9）. And their Li-storage properties were investigated as anode materials for lithium rechargeable batteries. The pure Cr2O3 works as an adhesive interface to strengthen the connections between Li4Ti5O12 par- ticles, providing more electric conduction channels, and reduce the inter-particle resistance. Moreover, Li2Cr2O3, formed by the lithiation of Cr2O3, can further stabilize LiTTi5O12 with high electric conductivity on the surface of particles. While in the acid chromium solution （pH=3.2） modification, besides Cr2O3, Li2CrO4 and TiO2 phases were also found in the final product. Li2CrO4 is toxic and the presence of TiO2 is not welcome to im- prove the electrochemical performance of Li4Ti5O12 microspheres. The reversible capacity of 1% Cr2O3-coated sample with the basic chromium solution modification was 180 mAh/g at 0.1 C, and 134 mAh/g at 10 C. Moreover, it was even as high as 127 mAh/g at 5 C after 600 cycles. At -20 ℃, its reversible specific capacity was still as high as 118 mAh/g.

Recent Progress in Large-Area Perovskite Photovoltaic Modules

Perovskite solar cells(PSCs)have undergone a dramatic increase in laboratory-scale effi ciency to more than 25%,which is comparable to Si-based single-junction solar cell effi ciency.However,the effi ciency of PSCs drops from laboratory-scale to large-scale perovskite solar modules(PSMs)because of the poor quality of perovskite fi lms,and the increased resistance of large-area PSMs obstructs practical PSC applications.An in-depth understanding of the fabricating processes is vital for precisely controlling the quality of large-area perovskite fi lms,and a suitable structural design for PSMs plays an impor-tant role in minimizing energy loss.In this review,we discuss several solution-based deposition techniques for large-area perovskite fi lms and the eff ects of operating conditions on the fi lms.Furthermore,diff erent structural designs for PSMs are presented,including the processing technologies and device architectures.

Nanowire-based transparent conductors for flexible electronics and optoelectronics

As the necessary components for various modern electronic and optoelectronic devices, novel transparent electrodes(TEs) with the low cost, abundance features, and comparable performance of indium tin oxide(ITO) are inquired materials. Metal nanowires(NWs) with the excellent photoelectric properties as next-generation TE candidates have widely applications in smart optoelectronic devices such as electronic skins, wearable electronics, robotic skins, flexible and stretchable displays. This review describes the synthetic strategies for the preparation of metal NWs, the assemble process for metal NW films,and the practical aspects of metal NW films with the desired properties in various low-cost, flexible,and solution-based photoelectric devices.

Heterostructures in two-dimensional colloidal metal chalcogenides:Synthetic fundamentals and applications

As a new class of two-dimensional materials, two-dimensional (2D) heterostructures constructed from metal chalcogenides (MCs) have been gaining tremendous attention due to their unprecedented physical and chemical phenomena, mainly originated from their distinct structural features such as composition, architecture type, spatial arrangement of each component, crystal structure, exposed facet and interface, dimensionality in their heterostructures. Towards the realization of practical applications, synthetic approaches need a rational design with a variety of architecture types including laterally-combined, vertically-aligned, and conformally-coated 2D MC heterostructures. Among various synthetic routes, solution-based synthesis is thought of as an alternative to fabrication through high-cost setups since it can control those structural features in a cheap fashion. This review presents recent progress on solution-based synthesis to produce various 2D MC heterostructures with a focus on the synthetic fundamentals in terms of thermodynamic and kinetic aspects related to the growth mechanism. Four different synthetic approaches are reviewed: seeded growth, cation exchange reaction, colloidal atomic layer deposition, direct synthesis including one-step process and modified electrochemical method. We also provide some representative applications of 2D MC heterostructures and their hybrid composites in various fields including optoelectronics, thermoelectrics, catalysis, and battery. Finally, we offer an insight into challenges and future directions in a synthetic improvement of 2D MC heterostructures.

Bi_(2)S_(3) Nanotubes:Facile Synthesis and Growth Mechanism

Synthesis of tubular nanomaterials has become a prolific area of investigation due to their wide range of applications.A facile solution-based method has been designed to fabricate uniform Bi_(2)S_(3)nanotubes with average size of 20 nm×160 nm using only bismuth nitrate(Bi(NO_(3))_(3)·5H_(2)O)and sulfur powder(S)as the reactants and octadecylamine(ODA)as the solvent.Powder X-ray diffraction(XRD),transmission electron microscopy(TEM),high-resolution TEM(HRTEM),and energy dispersive spectroscopy(EDX)experiments were employed to characterize the resulting Bi_(2)S_(3)nanotubes and the classic rolling mechanism was applied to explain their formation process.

Carbon nanodots:A metal-free,easy-to-synthesize,and benign emitter for light-emitting electrochemical cells

Light-emitting electrochemical cells(LECs)can be fabricated with cost-efficient printing and coating methods,but a current drawback is that the LEC emitter is commonly either a rare-metal complex or an expensive-to-synthesize conjugated polymer.Here,we address this issue through the pioneering employment of metal-free and facile-to-synthesize carbon nanodots(CNDs)as the emitter in functional LEC devices.Circular-shaped(average diameter=4.4 nm)and hydrophilic CNDs,which exhibit narrow cyan photoluminescence(peak=485 nm,full width at half maximum=30 nm)with a high quantum yield of 77%in dilute ethanol solution,were synthesized with a catalyst-free,one-step solvothermal process using low-cost and benign phloroglucinol as the sole starting material.The propensity of the planar CNDs to form emission-quenching aggregates in the solid state was inhibited by the inclusion of a compatible 2,7-bis(diphenylphosphoryl)-9,9’-spirobifluorene host compound,and we demonstrate that such pristine host-guest CND-LECs turn on to a peak luminance of 118 cd·m^(−2)within 5 s during constant current-density driving at 77 mA·cm^(−2).

Recent advances and opportunities in MXene-based liquid crystals

The recent progress on the liquid crystalline(LC)dispersion of two-dimensional(2D)transition metal carbides(MXenes)has propelled this unique nanomaterial into a realm of high-performance architectures,such as films and fibers.Additionally,compared to architectures made from typical non-LC dispersions,those derived from LC MXene possess tunable ion transport routes and enhanced conductivity and physical properties,demonstrating great potential for a wide range of applications,such as electronic displays,smart glasses,and thermal camouflage devices.This review provides an overview of the progress achieved in the production and processing of LC MXenes,including critical discussions on satisfying the required conditions for LC formation.It also highlights how acquiring LC MXenes has broadened the current solution-based manufacturing paradigm of MXene-based architectures,resulting in unprecedented performances in their conventional applications(e.g.,energy storage and strain sensing)and in their emerging uses(e.g.,tribology).Opportunities for innovation and foreseen challenges are also discussed,offering future research directions on how to further benefit from the exciting potential of LC MXenes with the aim of promoting their widespread use in designing and manufacturing advanced materials and applications.

Precision Control of Amphoteric Doping in Cu_(x)Bi_(2)Se_(3) Nanoplates

Copper-doped Bi_(2)Se_(3)(Cu_(x)Bi_(2)Se_(3))is of considerable interest for tailoring its electronic properties and inducing exotic charge correlations while retaining the unique Dirac surface states.However,the copper dopants in Cu_(x)Bi_(2)Se_(3) display complex electronic behaviors and may function as either electron donors or acceptors depending on their concentration and atomic sites within the Bi_(2)Se_(3) crystal lattice.Thus,a precise understanding and control of the doping concentration and sites is of both fundamental and practical significance.Herein,we report a solution-based one-pot synthesis of Cu_(x)Bi_(2)Se_(3) nanoplates with systematically tunable Cu doping concentrations and doping sites.Our studies reveal a gradual evolution from intercalative sites to substitutional sites with increasing Cu concentrations.The Cu atoms at intercalative sites function as electron donors while those at the substitutional sites function as electron acceptors,producing distinct effects on the electronic properties of the resulting materials.We further show that Cu_(0.18)Bi_(2)Se_(3) exhibits superconducting behavior,which is not present in Bi_(2)Se_(3),highlighting the essential role of Cu doping in tailoring exotic quantum properties.This study establishes an efficient methodology for precise synthesis of Cu_(x)Bi_(2)Se_(3) with tailored doping concentrations,doping sites,and electronic properties.