Resources Chemicals and Materials最新文献

Carbon materials (graphite or C/C composites) are widely used in aerospace applications due to their unique performance advantages, including low density, high specific strength and low coefficients of thermal expansion. However, carbon materials are highly susceptible to destructive oxidation in high-temperature oxygen-containing environments, limiting their application scope and service life. Coating technology is an effective approach for solving the above problem, and ceramic coatings are the most widely used protective system. In this review, the latest research progress regarding different types of silicon carbide-based antioxidation and anti-ablation ceramic coatings on the surfaces of carbon materials is described, and the protective properties and mechanism analysis of the SiC and modified SiC coatings by ultrahigh-temperature ceramic borides, carbides, silicides and other reinforcements are elucidated. In addition, the current main challenges of ceramic coatings are carefully analysed, and the perspectives for the future development of ceramic protection coatings are also discussed.

CdS nanospheres were grown on indium tin oxide (ITO) substrate using a hydrothermal method. The crystal structure, morphology and electronic structure of the samples synthesized were characterized in detail. The results confirm that the crystallinity, size, crystal defects of the CdS nanospheres and the film thickness of CdS photoelectrodes can be tuned by varying the precursor Cd²⁺ concentration. Combined with charge transfer dynamics analysis, it can be found that proper particle size and film thickness, as well as fewer defects, will result in better charge separation efficiency of the prepared CdS/ITO photoelectrodes, thereby exhibiting better photoelectrochemical performance for water splitting. The optimized CdS/ITO photoelectrode synthesized with a Cd²⁺ concentration of 0.14 mol·L⁻¹ gave a photocurrent density of 5.10 mA·cm⁻² at potential of 1.23 V versus the reversible hydrogen electrode (RHE), under a simulated solar illumination of 100 mW·cm⁻².

It is well known that calcium oxide (CaO) has better catalytic efficiency than most heterogeneous catalysts in many transesterification reactions. However, the gradual deactivation problem prevents its large-scale application in industry. In this paper, the deactivation mechanism of CaO in a fixed-bed reactor is investigated based on the transesterification reaction of propylene carbonate and methanol. The leaching amount of CaO during the reaction was estimated by the concentration of Ca in the products. The pretreated and recovered catalysts were characterized by FT-IR, XRD, TG-MS and SEM-EDS. It is evident from experiments and characterization that the deactivation process of CaO is accompanied by the leaching of calcium species and the generation of CaCO₃, which are also verified by DFT calculations. At high temperature and high weight hourly space velocity, the deactivation was attributed to the formation of dense CaCO₃ shell, which prevents the contact between the feedstock and the active species inside.

For typical Mg-Zn-Zr alloys, exhilaratingly high strength of a yield strength (YS) higher than 300 MPa can hardly be attained by traditional rolling. In this paper, we compare the mechanical properties and strengthening mechanisms of the Mg-5Zn-0.6Zr alloys having a homogeneous dynamical recrystallized microstructure and a bimodal microstructure with high-density nano substructures. The Mg-5Zn-0.6Zr alloy with the bimodal microstructure (rolled at 150 °C with a thickness reduction of 60%) exhibits a YS of 332 MPa, an ultimate tensile strength (UTS) of 360 MPa, and an elongation of 5%. The high strength is attributed to the microstructure with high-density nano substructures, high-density nano (Mg, Zr)Zn₂ precipitates, ultrafine recrystallized grains, and strong basal texture. In comparison, the Mg-5Zn-0.6Zr alloy with homogeneous microstructure (rolled at 200 °C with a thickness reduction of 70%) exhibits a YS of 209 MPa, an UTS of 317 MPa, and an elongation of 17%, which contains coarser recrystallized grains, coarser precipitates, weaker texture, and lower density of dislocations, further resulting in low strength. The difference between the strengthening mechanism in two kinds of microstructure is discussed in detail. The results facilitate the preparation of wrought Magnesium alloy with high strength by reasonable microstructure construction.

In recent years, bio-based polymeric materials have attracted increased attention owing to their distinctive properties, including richness, sustainability, environmental friendliness, and biodegradability. This article reviews the recent developments and potential trends of research on bio-based polymers synthesized from various renewable resources. It covers the resources and structures of bio-based monomers, the methods of synthesis and properties of bio-based thermoplastics and thermosets, the production of bio-based composites and the fabrication of functional bio-based polymers. Finally, the technological and future challenges related to enabling these materials to apply in the industry have been discussed, together with the potential solutions or directions.

The utilization of fossil fuels has brought unprecedented prosperity and development to human society, but also caused environmental pollution and global warming triggered by excess greenhouse gases emission. For one thing, the excess emission of carbon dioxide (CO₂), which has a negative impact on global temperature and ocean acidity, needs to be controlled. For another, the depletion of fossil fuels will eventually force people to seek alternative carbon sources to maintain a sustainable economy. Thus, using renewable energy to convert CO₂ and biomass into value-added chemicals and fuels is a promising method to overcome urgent problems. The hydrogenation of CO₂ is very important to mitigate the greenhouse effect caused by CO₂, while biomass conversion can produce alternative renewable biofuels and green chemicals. As a kind of promising catalyst, heterogeneous single-atom catalyst (SAC) has received extensive attention in the past decades. SACs combine the advantages of homogeneous catalysts with uniform active sites and heterogeneous catalysts that are easily separable. In this review, we will give a comprehensive overview of the latest progress in CO₂ selective hydrogenation and biomass conversion via SACs.

Hard carbon is considered as the most commercially applicable anode for sodium-ion batteries. Lignin has the characteristics of sustainable, low cost, high carbon content (>60%) and abundant oxygen functional groups, which is expected to be used as a promising candidate precursor for low-cost hard carbons. The structure and electrochemical performances of hard carbons could be regulated by adjusting carbonization temperature. The microstructure and electrochemical performance of LDHC anode are highly dependent on the carbonization temperature. Increasing carbonization temperature could reduce specific surface area and improve initial coulombic efficiency. The slope and plateau capacity of the LDHC anode could also be adjusted by changing the carbonization temperature. The LDHC prepared at 1200 °C showed the best sodium-ion storage performance, with an initial coulombic efficiency of 78.9% and a reversible sodium-ion storage capacity of 284.7 mAh g⁻¹.

The removal and enrichment of pollutants in industrial wastewater using efficient adsorption processes have been a hot scientific topic in the field of environmental chemistry and green chemistry. Compared with the progress in the design, synthesis, and performance of polyethyleneimine-modified adsorbent materials at home and abroad, there are few reviews on how to modify polyethyleneimine (PEI) in adsorbent materials through functional group reactions. Therefore, this review attempts to provide a systematic review of how PEI can prepare adsorbent materials by functional group reaction and the adsorption mechanism of inorganic metal ions, phosphates, and dyes in wastewater by PEI. On this basis, future research directions of adsorbent materials are prepared by PEI prospects.

The 2022′s Youth Forum on Resources Chemicals and Materials was held on November 12–13, 2022, in Shenyang, Liaoning Province. Panel discussions focus on the cutting-edge researches on “Fine chemicals and advanced alloy materials” and “Utilization of fossil and renewable carbon resources”. This perspective summarizes the major directions of scientific research and technical developments aligned in the discussions. Fine chemical industry tends to pursue green and low-carbon products, intelligent product design, and start manufacturing. In recent years, great efforts have been made for transformation of cellulose into advanced electronic as well as life-service bio-materials and to the high-selectivity extraction of bio-base aromatic chemicals from lignin. Concerning high-end alloy materials, regulating deformation mechanism of crystal to construct bimodal microstructure seems highly prospective in harmonizing precipitate hardening effect and plastic deformation capacity. As we know, utilization of fossil carbon resources constitutes the major anthropogenic carbon emissions, and the related innovations thus should be, for possibly a long period, on increasing energy production efficiency and low-carbon cascaded conversion of fossil fuels, especially of coal.