Review of the fabrication and application of porous materials from silicon-rich industrial solid waste

Porous materials have promise as sound insulation, heat barrier, vibration attenuation, and catalysts. Most industrial solid wastes, such as tailings, coal gangue, and fly ash are rich in silicon. Additionally, a high silicon content waste is a potential raw material for the syn- thesis of silicon-based, multi-porous materials such as zeolites, mesoporous silica, glass-ceramics, and geopolymer foams. Representative sil- icon-rich industrial solid wastes (SRISWs) are the focus of this mini review of the processing and application of porous silicon materials with respect to the physical and chemical properties of the SRISW. The transformation methods of preparing porous materials from SRISWs are summarized, and their research status in micro-, meso-, and macro-scale porous materials are described. Possible problems in the application of SRISWs and in the preparation of functional porous materials are analyzed, and their development prospects are discussed. This review should provide a typical reference for the recycling and use of industrial solid wastes to develop sustainable “green materials.”

Metal-organic frameworks for electrochemical reduction of carbon dioxide: The role of metal centers

Direct electrochemical reduction of CO2 into valuable chemicals and fuel is one of the most promising approaches to address the current energy crisis and lower CO2 emission.Recently,numerous metal-organic framework(MOF)and their derived materials have extensively been developed as electrocatalysts for CO2 reduction owing to their unique structure including porosity,large specific surface area,and tunable chemical structures.In this review,the recent progress of MOF-based electrocatalysts for CO2 reduction was summarized and discussed.Detailed discussions mainly focus on the synthesis and mechanism of pristine MOFs and MOF-derived materials for electrocatalytic CO2 reduction.These examples are expected to provide clues to rational design and synthesis of stable and high-performance MOFs-based electrocatalysts for CO2 reduction.

Hierarchical cobalt phenylphosphonate nanothorn flowers for enhanced electrocatalytic water oxidation at neutral pH

Cobalt-based phosphate/phosphonates are a class of promising water oxidation catalysts at neutralpH.Herein,we reported a facile hydrothermal synthesis of various nanostructured cobalt phe-nylphosphonates.It is found that the number of hydroxyl group of structure-directing reagent iscrucial for the construction of 3D hierarchical structures including hierarchical nanosheet flow-er-like assemblies and nanothorn microsphere.These samples were characterized by scanningelectron microscopy,transmission electron microscopy,X-ray diffraction,infrared,and X-ray pho-toelectron spectroscopy techniques.They can act as highly efficient electrocatalysts for the oxygenevolution reaction at neutral pH.Among these,hierarchical cobalt phenylphosphonate nanothornflowers present excellent performance,affording a current density of 1 mA cm^-2 required a smalloverpotential of 393 mV.This work offers a new clue to develop high-performance metal phospho-nate/phosphate catalysts toward electrochemical water oxidation.

Identification of ions present in LiF-DyF_3 melts and the mechanism of Dy_2O_3 dissolution therein

Herein, the present paper were attempted to identify ions in LiF-DyF_3 melts according to the law of decreasing primary crystallization temperature and model analysis. Specifically.the primary crystallization temperatures of LiF-DyF_3 and LiF-DyF_3-Dy_2O_3 melts with various DyF_3 and Dy_2O_3 contents were determined by differential scanning calorimetry(DSC), and reactions occurring in the above melts were investigated using ideal dilute solution(Temkin and Flood) models. Moreover, crystal phases produced by rapid solidification of LiF-DyF_3, LiF-Dy_2O_3, DyF_3-Dy_2O_3, and LiF-DyF_3-Dy_2O_3 melts were identified by X-ray diffraction(XRD) analysis. The primary crystallization temperature of LiF-DyF_3 melts exhibits an approximately linear decrease with increasing molar fraction of DyF_3, and the general formula of complex ions in these melts is expressed as DyF_x^((3-x)),e.g., DyF_4^-. Finally, we investigated the dissolution of Dy_2O_3 in LiF-DyF_3 melts, showing that it was chemical in nature and afforded Dy_(1+x)O_(3x)F_(3-3x) and DyOF.

Gigantic electric-field-induced second harmonic generation from an organic conjugated polymer enhanced by a band-edge effect

Electric-field-induced second harmonic generation(EFISH),a third-order nonlinear process,arises from the interaction between the electric field of an external bias and that of two incident photons.EFISH can be used to dynamically control the nonlinear optical response of materials and is therefore promising for active nonlinear devices.However,it has been challenging to achieve a strong modulation with EFISH in conventional nonlinear materials.Here,we report a large tunability of an EFISH signal from a subwavelength-thick polymer film sandwiched between a transparent electrode and a metallic mirror.By exploiting the band-edge-enhanced third-order nonlinear susceptibility of the organic conjugated polymer,we successfully demonstrate a gigantic EFISH effect with a modulation ratio up to 422%V^(−1) at a pumping wavelength of 840 nm.The band-edge-enhanced EFISH opens new avenues for modulating the intensity of SHG signals and for controlling nonlinear electro-optic interactions in nanophotonic devices.

Electrochemical behavior of dysprosium(Ⅲ) in eutectic LiF-DyF3 at tungsten and copper electrodes

Electrochemical behavior of dysprosium(Dy)ions in LiF-DyF3(24 mol%)was investigated by cyclic voltammetry,chronoamperometry and chronopotentiometry.Dy-Cu alloy samples were prepared by constant-potential electrolysis in LiF-DyF3(24 mol%)at the Cu electrode.The Cu5 Dy and Cu phases were characterized by an X-ray diffractometer and a scanning electron microscope equipped with an energy dispersive spectrometer.The results show that the reduction of Dy(Ⅲ)ions in a LiF-DyF3(24 mol%)molten salt system is found to be a quasi-reversible diffusion-controlled process which occurs via a onestep reaction involving the transfer of three electrons.The electro-crystallization processes of the Dy metal at the W electrode and the mode of nucleation confirm that progressive nucleation is dominant at high concentrations of Dy ions in the LiF-DyF3 salt.At lower concentrations,the instantaneous nucleation of Dy with three-dimensional growth of the nuclei is dominant.

Wheel‐Shape Heterometallic Ti10M2‐oxo Clusters (M = Ni, Co) with Effective Visible Light Absorption

Summary of main observation and conclusion In order to make visible light harvest crystalline polyoxo‐titanium clusters, we initially used transition metal pivalate complexes in this system and prepared successfully two isostructural compounds,[Ti10M2(PPO)4(μ3‐O)8(μ2‐O)4(PA)12(MeCN)4]·4HPA (PPOA = phenylphosphonic acid, HPA = propionic acid, M = Ni, PTC‐52‐Ni;M = Co PTC‐52‐Co). Single‐crystal X‐ray diffraction study showed that these two complexes possessed wheel‐shape heterometallic Ti10M2‐oxo clusters. The absorption bands of these two compounds shift effectively toward the visible‐light region. Furthermore, their photocurrent response has also been studied.

Synthesis, Crystal Structure, and Visible Light Responses of Ti4Cu4-Oxo Clusters with Mixed Valence Copper Ions

Summaryof main observation and conclusion In order to extend the absorption spectrum of polyoxo-titanium clusters into the visible region,two new heterometal-oxo clusters Ti4CuII2CuI2(μ3-O)6(benzoate)10(MeCN)4(PTC-153)and Ti4CuII2CuI2(μ3-O)6(benzoate)8(CH3COO)2(MeCN)4(PTC-154)were success-fully synthesized.Single-crystal X-ray diffraction and X-ray photoelectron spectroscopy studies showed that these two heterometallic Ti4Cu4-oxo clusterspossessed Chinese knot-shape structure and mixed valence Cu^1+/2+ions.UV-visible spectroscopyanalysis demonstrated that the visible light region ab-sorption of PTC-153and PTC-154 could be significantly enhanced by doping copper.Furthermore,their visible-light driven photocurrent responses were studied by using samples of PTC-153and PTC-154as electrode precursors.

Effect of LiCoO_(2)on the positive temperature coefficient effect(PTC)properties of semiconductive composites and its ability to inhibit space charge injection

The semiconductive shield layer is between the conductive core and the insulation layer of high voltage direct current transmission cables and plays an important role in suppressing the accumulation of space charge in the insulation layer.Since the prevalent positive temperature coefficient effect(PTC)of the semiconducting layer leads to cable ageing and failure,this paper proposes the use of lithium cobaltate to modify the semiconducting shield to suppress its PTC effect and improve its ability to inhibit space charge injection.The ionic conductor LiCoO_(2)was prepared by the sol–gel method.LiCoO_(2)particles with particle sizes ranging from tens to hundreds of nanometres were obtained by ball milling.The prepared LiCoO_(2)was used as a filler to modify the carbon black(CB)/ethylene vinyl acetate copolymer(EVA)/low density polyethylene(LDPE)composites.After melt blending and moulding cross-linking,LiCoO_(2)/CB/EVA/LDPE semiconductive shielding specimens were successfully fabricated.Resistivity,Thermally Stimulated Depolarisation Currents(TSDC),and pulsed electroacoustic measurements were conducted for the prepared specimens.The PTC effect,which is common in polymer composites,was successfully suppressed,and the PTC strength was reduced by 17%.The resistivity of the semiconductive shielding layer was significantly reduced.The ability of the semiconducting shield to inhibit space charge injection from the conductive core to the insulation layer was significantly improved.When LiCoO_(2)content is 0.5 wt%,the semiconductive shielding layer has the best performance,and the space charge in the insulation layer was reduced by 70%compared to the undoped semiconducting shield.

The effect of a conductive polyaniline/carbon black composite on the performance of a semiconductive layer

In this study,conductive polyaniline(PANI)ribbons were introduced to a semi-conductive layer to improve the conductivity stability of the layer during thermal expansion and enhance its ability to inhibit charge injection into the insulating layer.To maximise the effect of PANI,PANI and carbon black(CB)were preformed into a uniformly dispersed composite,which was then added to the polymer matrix of the semiconductive layer.The experimental results show that the resistivity of the semi-conductive layer containing the PANI/CB composite is more stable during thermal expansion than that of the semiconductive layer only doped with CB.This is attributed to the conductive CB network being enhanced by the PANI ribbons.In addition,due to the unique conductivity mechanism and high dielectric constant of PANI,the semiconductive layer has a strong ability to inhibit space charge injection into the insulating layer.