Synergistic Effect of In2O3/NC-Co3O4 Interface on Enhancing the Redox Conversion of Polysulfides for High-Performance Li-S Cathode Materials at Low Temperatures.

Lithium-sulfur (Li-S) batteries are considered as a promising energy storage technology due to their high energy density; however, the shuttling effect and sluggish redox kinetics of lithium polysulfides (LiPSs) severely deteriorate the electrochemical performance of Li-S batteries. Herein, we report a novel configuration wherein In2O3 and Co3O4 are incorporated into N-doped porous carbon as a sulfur host material (In2O3@NC-Co3O4) using metal-organic framework-based materials to synergistically tune the catalytic abilities of different metal oxides for different reaction stages of LiPSs, achieving a rapid redox conversion of LiPSs. In particular, the introduction of N-doped carbon improved the electron transport of the materials. The polar interface of In2O3 and Co3O4 anchors both long- and short-chain LiPSs and catalyzes long-chain and short-chain LiPSs, respectively, even at low temperatures. Consequently, the Li-S battery with In2O3@NC-Co3O4 cathode materials delivered an excellent discharge capacity of 1042.4 mAh g-1 at 1 C and a high capacity retention of 85.1% after 500 cycles. Impressively, the In2O3@NC-Co3O4 cathode displays superior performances at high current density and low temperature due to the enhanced redox kinetics, delivering 756 mAh g-1 at 2 C (room temperature) and 755 mAh g-1 at 0.1 C (-20 °C).

Synergistic utilization, critical mechanisms, and environmental suitability of bauxite residue (red mud) based multi-solid wastes cementitious materials and special concrete.

The energy consumption and carbon emissions in the construction field, coupled with the accumulation of various industrial solid wastes, particularly bauxite residue (red mud), represent formidable barriers to sustainable development. The synergistic utilization of bauxite residue (red mud) in cementitious materials and special concrete is widely considered one of the most practical approaches for these issues. In this comprehensive review, characteristics and composition of red mud worldwide were investigated. By comparing and reviewing the latest research, the current achievements in applying red mud with various solid wastes in cementitious materials and special concrete were discussed. In addition, critical mechanisms and environmental suitability issues are emphasized. In conclusion, the present work culminates in identifying the challenges faced and opportunities for progressing in synergizing red mud and multi-solid wastes, which will contribute to the international research community for sustainable development in the industry.

Approaches for the Treatment and Resource Utilization of Electroplating Sludge.

The disposal of electroplating sludge (ES) is a major challenge for the sustainable development of the electroplating industry. ESs have a significant environmental impact, occupying valuable land resources and incurring high treatment costs, which increases operational expenses for companies. Additionally, the high concentration of hazardous substances in ES poses a serious threat to both the environment and human health. Despite extensive scholarly research on the harmless treatment and resource utilization of ES, current technology and processes are still unable to fully harness its potential. This results in inefficient resource utilization and potential environmental hazards. This article analyzes the physicochemical properties of ES, discusses its ecological hazards, summarizes research progress in its treatment, and elaborates on methods such as solidification/stabilization, heat treatment, wet metallurgy, pyrometallurgy, biotechnology, and material utilization. It provides a comparative summary of different treatment processes while also discussing the challenges and future development directions for technologies aimed at effectively utilizing ES resources. The objective of this text is to provide useful information on how to address the issue of ES treatment and promote sustainable development in the electroplating industry.

Application of the Industrial Byproduct Gypsum in Building Materials: A Review.

The industrial byproduct gypsum is a general term for byproducts discharged from industrial production with calcium sulfate as the main ingredient. Due to the high number of impurities and production volume, the industrial byproduct gypsum is underutilized, leading to serious environmental problems. At present, only desulfurization gypsum and phosphogypsum have been partially utilized in cementitious materials, cement retarders, etc., while the prospects for the utilization of other byproduct gypsums remain worrying. This paper mainly focuses on the sources and physicochemical properties of various types of gypsum byproducts and summarizes the application scenarios of various gypsums in construction materials. Finally, some suggestions are proposed to solve the problem of the industrial byproduct gypsum. This review is informative for solving the environmental problems caused by gypsum accumulation.

Nanorod In2O3@C Modified Separator with Improved Adsorption and Catalytic Conversion of Soluble Polysulfides for High-Performance Lithium-Sulfur Batteries.

The shuttle effect of soluble lithium polysulfides (LiPSs) poses a crucial challenge for commercializing lithium-sulfur batteries. The functionalization of the separator is an effective strategy for enhancing the cell lifespan through the capture and reuse of LiPSs. Herein, a novel In2O3 nanorod with an ultrathin carbon layer (In2O3@C) was coated on a polypropylene separator. The results demonstrate the adsorption and catalysis of In2O3 on polysulfides, effectively inhibiting the shuttle effect and improving the redox kinetics of LiPSs. Besides, the ultrathin carbon layer increases the reaction sites and accelerates the electrochemical reaction rate. The cell with the In2O3@C interlayer displays excellent reversibility and stability with a 0.029% capacity decay each cycle in 2000 cycles at 2C. In addition, the In2O3@C interlayer significantly improves the cell performance under high current (888.2 mA h g-1 at 2C and room temperature) and low temperature (1007.8 mA h g-1 at 0.1C and -20 °C) conditions.

Investigation of the Pozzolanic Activity Improvement of Yellow Phosphorus Slag with Thermal Activation.

Yellow phosphorus slag (YPS) is a byproduct from the production of yellow phosphorus. It has potential pozzolanic activity and can be used as a supplementary cementitious material. However, the early strength of cement mortar decreases significantly with increasing YPS dosage, which restricts the utilization of YPS in cement and concrete. This study aimed to increase the pozzolanic activity of YPS ash by thermal activation. The strength method, alkali dissolution method and polymerization degree method were used to evaluate the effect of thermal activation at different temperatures on the pozzolanic activity of YPS ash. The results showed that YPS ash calcined at 800 °C helps to enhance the early strength because the fluorine in cuspidine (Ca4Si2O7F2) is insoluble, reducing the retarding effect on the mortar. The higher late strength of YPS ash calcined at 100 °C was due to the low polymerization degree of [SiO4]. The pozzolanic activity of YPS ash is positively correlated with the dissolution concentration of (Si + Al) and the compressive strength and negatively associated with the polymerization degree. This paper shows a possibility for the large-scale utilization of YPS.

Effect of Phosphorus Slag Admixture on the Properties and Hydration Mechanism of Circulating Fluidized Bed Fly Ash-Based Multi-Solid Waste Cementitious Material.

This research aims to reveal the effect of phosphorus slag (PS) admixtures on the properties and hydration mechanism of circulating fluidized bed fly ash (CFA)-based multi-solid waste cementitious material (CWM). The results indicate that PS as an admixture is more helpful for improving the performance of CWM systems compared with blast furnace slag with a high specific surface area (HBFS) and gasification slag (GS). In this work, CWM2 is prepared with 30 wt.% CFA, 10 wt.% red mud (RM), 20 wt.% blast furnace slag (BFS), 10 wt.% PS, and 30 wt.% cement clinker (CC). The compressive strength and expansion value of CWM2 are the optimal (51.15 MPa and 0.70 mm) when the mass ratio of (Ca + Na)/(Si + Al) is 0.84, which can meet the requirements of 42.5 fly ash Portland cement. In addition, the polymerization degree of CWM2-28 days is the optimum (51.57%) because [PO4] and [SiO4] combine to improve its polymerization structure. The main hydration products are C-S-H gel, C/N-A-S-H gel, and ettringite in CWM, which are conducive to improve the compactness of the micromorphology. In addition, the consolidation of Na, As, Cd, and Hg is promoted in CWM2 by physical encapsulation and charge balance, which meet the drinking water requirements of the World Health Organization (WHO). Therefore, this work provides a new idea for the application of PS as an admixture in CFA-based multi-solid waste cementitious material.

Comprehensive Understanding of Aluminosilicate Phosphate Geopolymers: A Critical Review.

Aluminosilicate phosphate (ASP) geopolymers are a new kind of green cementitious materials synthesized from aluminosilicate precursors and acidic activators (phosphoric acid or phosphate), which have received extensive attention from researchers because of their excellent and unique characteristics. The current investigation indicates that ASP geopolymers have the characteristics of a low-carbon synthesis process, high mechanical properties (e.g., the highest compressive strength can reach 146 MPa), a strong heat resistance (e.g., withstanding a high temperature of 1500 °C), and excellent dielectric properties. These excellent properties make them have broad application prospects in the fields of new building materials, coating materials, insulating materials, and heavy metal curing. Based on the research findings of approximately 85 relevant literatures on ASP geopolymers in past decades, this paper focuses on the latest research progress of ASP geopolymers from the perspectives of synthesis processes, performances, modifications, and application developments. In addition, this study summarizes the key problems existing in the current research of ASP geopolymers and suggests their possible applications in the future, which will help to provide directions for further research activities of relevant researchers.

Frost Resistance and Mechanism of Circulating Fluidized Bed Fly Ash-Blast Furnace Slag-Red Mud-Clinker Based Cementitious Materials.

The motivation of this work is to enhance the long-term frost resistance of circulating fluidized bed fly ash (CFA)-based multisolid waste cementitious material (CSM). In this research, CSM2 is prepared by 30 wt.% CFA, 20 wt.% blast furnace slag (BFS), 10 wt.% red mud (RM), 10 wt.% phosphorus slag (PS), and 30 wt.% cement clinker (CC). The strength and mass of CSM are detected by a press and electronic balance. The hydration products, polymerization degree, thermogravimetric, micromorphology, pore structure, and harmful element leaching are detected by XRD, MAS NMR, TG-DTG, SEM-EDX, MIP, and ICP-MS. The major findings indicate that the strength loss, mass loss, and strength of CSM2 after 25 freeze-thaw cycles (CSM2-25) are 2.35%, 0.36%, and 49.95 MPa, respectively, which is superior to other CSMs and still meets the performance requirements of fly ash Portland cement 42.5#. The main hydration products are C-S-H gel, C/N-A-S-H gel, and ettringite during the freeze-thaw cycle. The polymerization degree and thermogravimetric loss of hydration products in CSM2-25 are 50.65% and 12.82 wt.%, respectively, which are higher than those of other CSMs under the synergy of CFA, BFS, RM, and PS. In addition, the microscopic results show that the interface between the paste and aggregate, micromorphology, and pore structure of CSM2-25 are the densest when the mass ratio of Ca/(Si + Al) is 0.81. These characteristics are beneficial to the improvement of long-term frost resistance in CSM2. Finally, the leaching results of harmful elements in CSM2 after 25 freeze-thaw cycles still meet the WHO standard of drinking water. Therefore, this work provides a reliable reference for the preparation of green cementitious materials with great frost resistance by using CFA, BFS, RM, and PS.

Hydration and Properties of Magnesium Potassium Phosphate Cement Modified by Granulated Blast-Furnace Slag: Influence of Fineness.

Magnesium potassium phosphate cement (MKPC) is an excellent rapid repair material for concrete, and many mineral admixtures have been applied to promote its performance. This study focuses on the quantitative characterization of the physical and chemical contributions of granulated blast-furnace slag with various finenesses to the performance development of MKPC. It was found that the addition of slag could increase the setting time, which is mainly due to the dilution of cement. Fine slag tends to decrease the fluidity of MKPC mortar. The physical contributions of ordinary and ultrafine slag to the early performance of MKPC mortar are 23% and 30%, while the chemical contributions are only 6%~10%. At late ages, the physical contribution is less than 10% and the chemical contribution of slag is even slightly negative. The addition of slag is beneficial to the compact packing of MKPC, which is the main reason for the physical contribution. Slag could react in the MKPC system, and increasing the fineness significantly promotes the reaction kinetics.

Applications of Red Mud as a Masonry Material: A Review.

Red mud (RM) is a highly alkaline by-product produced by the aluminium industry. The total stockpile of RM in the world is evaluated to be close 4 billion tons, which caused serious soil and water pollution. The use of RM in masonry materials has proven to be a prospective strategy to alleviate the environmental problems caused by RM. During the past decades, various economical treatment methods have been developed for utilization of RM as a masonry material. There are two general categories of products using RM in masonry materials: sintered products and non-sintered products. In this review, the physicochemical properties of RM are introduced, and the different application scenarios for RM in masonry materials are summarized, which is valuable for solving the environmental problems caused by the accumulation of bauxite residue. Moreover, the potential environmental risks of utilizing RM are described. Finally, suggestions for solving the RM problem are proposed.

Circulating Fluidized Bed Fly Ash Mixed Functional Cementitious Materials: Shrinkage Compensation of f-CaO, Autoclaved Hydration Characteristics and Environmental Performance.

Circulating fluidized bed (CFB) fly ash is a by-product from CFB power generation, which is hard to utilize in cement because it contains f-CaO and SO3. This work aims to explore the mechanism of the shrinkage compensation of free-CaO (f-CaO) and the autoclaved hydration characteristics and environmental performance of CFB fly ash mixed cementitious materials (CMM). In this work, long-term volume stability of CMM is improved with the addition of CFBFA. These findings suggest that the compressive strength of sample CMM0.5 is the highest under both standard condition (67.21 MPa) and autoclaved condition (89.56 MPa). Meanwhile, the expansion rate (0.0207%) of sample CMM0.5 is the lowest, which proves the shrinkage compensation effect of f-CaO in CFBFA. The main hydration products of CMM0.5 are Ca2SiO4•H2O (C-S-H) gel, CaAl2Si2O7(OH)2•H2O (C-A-S-H) gel and Ca(OH)2. In addition, the high polymerization degree of [Si(Al)O4] and the densified microstructure are presented at the sample CMM0.5. The leaching results indicates that the heavy metals in CMM0.5 satisfies the WHO standards for drinking water due to physical encapsulation and charge balance. Therefore, this investigation provides a novel method of using CFB fly ash in cement.

Regulation of Substituent Effects on Configurations and Magnetic Performances of Mononuclear DyIII Single-Molecule Magnets.

A series of mononuclear DyIII compounds, [Dy(tmpd)3(4,4'-dmpy)] (1), [Dy(tffb)3(4,4'-dmpy)] (2), [Dy(tffb)3(5,5'-dmpy)] (3), and [Dy(tmpd)3(5,5'-dmpy)] (4) [tmpd = 4,4,4-trifluoro-1-(4-methoxyphenyl)-1,3-butanedione, tffb = 4,4,4-trifluoro-1-(4-fluorophenyl)-1,3-butanedione, 4,4'-dmpy = 4,4'-dimethyl-2,2'-bipyridyl, and 5,5'-dmpy = 5,5'-dimethyl-2,2'-bipyridyl], have been synthesized by modifying ß-diketonate ligands and capping N-donor co-ligands. DyIII ions in 1-4 possess N2O6 octacoordinated environments. Compounds 1 and 2 exhibit distorted trigonal dodecahedron configurations, while 3 and 4 display distorted square antiprismatic configurations. Systematic investigations of the alternating current measurements indicate the different magnetic relaxation dynamics with energy barriers (Ueff) of 66 K (1, 45 cm-1), 189 K, (2, 131 cm-1), 115 K (3, 79 cm-1), and 205 K (4, 142 cm-1). To deeply understand their different magnetic behaviors, the magnetic anisotropies of 1-4 were studied by ab initio calculations. From ab initio calculations, the energies of the first excited state (KD1) are consistent with the experimental Ueff under zero direct current field. Compound 4 presents the largest Ueff because of the smallest gX,Y and µQTM as well as the most strong axial crystal field parameters (CFPs) among compounds 1-4. The M versus H data exhibit butterfly-shaped hysteresis loops at 2 K for 1-4. The different coordination geometries, the magnetic dynamics, the electrostatic repulsion, and CFPs result from the different substituent effects of ligands, including the electronic effect, the steric effect, and the positions of substituted groups.

Graphdiyne-Modified Polyimide Separator: A Polysulfide-Immobilizing Net Hinders the Shuttling of Polysulfides in Lithium-Sulfur Battery.

Graphdiyne (GDY), a new type of carbon material with an electron-rich conjugated structure, has been investigated as a separator coating layer to enhance the electrochemical performance of lithium-sulfur (Li-S) battery. Acetylenic bond (-C≡C-C≡C-) and benzene ring in the GDY coating layer are experimentally verified to reversibly attract the soluble lithium polysulfides by chemical adsorption during cycling. Meanwhile, the shuttle effect of soluble polysulfides is further physically restricted by the GDY coating layer due to the evenly distributed pores (5.42 Å) and a consistent interlayer spacing (3.65 Å) of GDY. Moreover, GDY is a conducting carbon skeleton with high Li+ mobility that can improve the rate performance. Hence, Li-S battery with an as-prepared GDY coating layer shows excellent electrochemical performances including superior specific capacity, excellent rate performance, and low capacity attenuation rate. The high initial discharge capacity of 1648.5 mA h g-1 at 0.1C and 819.5 mA h g-1 even at a high rate of 2C is achieved by this novel separator. The initial capacity of 1112.9 mA h g-1 at 0.5C is retained to 816.7 mA h g-1 after 200 cycles with a low attenuation rate of 0.13% per cycle. Compared with other coated separators, these results show that the GDY coating layer endows the separator with superior electrochemical performances for Li-S battery.

Ligand ratio/solvent-influenced syntheses, crystal structures, and magnetic properties of polydentate Schiff base ligand-Dy(iii) compounds with ß-diketonate ligands as co-ligands.

Tuning the synthesis conditions and further regulating the magnetic dynamics of single-molecule magnets (SMMs) are crucial challenges for chemists. Some feasible approaches have been developed to understand magneto-structural correlations and regulate relaxation behaviors via rational design. Based on the solvent-induced effect or ligand ratio regulation, three new dysprosium(iii) coordination compounds, [Dy(L)(Dppd)]·solvent (1), [Dy(L)(Dppd)] (2) and [Dy(L)(Dppd)2]·solvent (3) (H2L = N,N'-bis(2-hydroxy-5-methyl-3-formylbenzyl)-N,N'-bis-(pyridin-2-ylmethyl)ethylenediamine, Dppd = dibenzoylmethane) have been successfully prepared. Compounds 1 and 2 are mononuclear structures. 3 is a dinuclear core in which the metal centers are bridged by two phenol-O atoms of one L2- ligand. Dy(iii) cations in compounds 1-3 present acta-coordination geometries. More interestingly, compounds 1 and 2 can be mutually transformed through the reversible single-crystal-to-single-crystal (SCSC) transformation under different solvent environments. The crystals of 1 and 2 underwent a dissolution-precipitation process and changed into 3, respectively. The distinct structures and magnetic properties were determined through combined structural, experimental and theoretical investigations.

Self-Assembly and External Modulation of a Flexible Porphyrin Derivative on Highly Oriented Pyrolytic Graphite.

With the aid of scanning tunneling microscopy, we have examined the two-dimensional hydrogen-bonded networks of carboxyl-functionalized porphyrin derivative H2TCPp molecules at the heptanoic acid/HOPG interface. Moreover, we have successfully modulated the self-assembly structure of H2TCPp by introducing 1,2-di(4-pyridyl)ethylene molecules into the assembled system. By performing density functional theory calculations, we also revealed the formation mechanisms of the different assemblies and the modulation process. Comparing the self-assembly structures at the liquid/solid interface with those in bulk crystals, we have obtained deep insight into the differences in H2TCPp assemblies between 2D and 3D networks. Furthermore, this research is expected to deepen our understanding of on-surface phenomena and to provide a feasible process toward 2D assembly regulation.

Synthetic Methodology for the Fabrication of Porous Porphyrin Materials with Metal-Organic-Polymer Aerogels.

A promising fabrication strategy used for designing porous porphyrin materials and a group of rigid carboxyl porphyrins based metal-organic-polymer aerogels (MOPAs) has been proposed recently. These newly synthesized MOPAs were exemplarily characterized by FT-IR, UV-vis-DRS, EDS, PXRD, TGA, SEM, TEM, and gas sorption measurements. A gelation study has shown that solvents, molar ratio, temperature, and peripheral carboxyl number in porphyrins all affect gel generation. The MOPA series exhibit eminent thermal stability, high removal efficiency in dye adsorption, versatile morphologies, and permanent tunable porosity; also the BET surface areas fall within the range 249-779 m(2) g(-1). All of the mentioned properties are significantly superior to some other porous materials, which enable these compounds to be potential candidates for dye uptake, gas storage, and separation.