2024 Vol. 9, No. 5

Research highlight
Abstract:
As global economic growth increases, the demand for energy sources boosts. While fossil fuels have traditionally satisfied this demand, their environmental influence and limited reserves require alternatives. Fossil fuel combustion contributes substantially to greenhouse gas emissions, with a pressing need to halve these emissions by 2030 and target net-zero by 2050. Renewable energy sources, contributing currently to 29% of global electricity, are viewed as promising substitutes. With wind energy's potential, Zheng's team developed a novel method to harness even low wind speeds using well-aligned nanofibers and an innovative “drop wind generator”. This system, combining moisture-saturated ionic liquid 3-Methyl-1-octylimidazolium chloride with specific nanofiber arrays, exploits wind-induced flows for energy conversion. This study highlights the vast untapped potential of low-speed wind as a sustainable energy source potentially for electronics.
Short review
Abstract:
Zeolites have been widely used as catalysts, ion-exchangers, and adsorbents in chemical industries, detergent industry, steel industry, glass industry, ceramic industry, medical and health field, and environmental field, and recently applied in energy storage. Seed-assisted synthesis is a very effective approach in promoting the crystallization of zeolites. In some cases, the target zeolite cannot be formed in the absence of seed zeolite. In homologous seed-assisted synthesis, the structure of the seed zeolite is the same to that of the target zeolite, while the structure of the seed zeolite is different to that of the target zeolite in the heterologous seed-assisted synthesis. In this review, we briefly summarized the heterologous seed-assisted syntheses of zeolites and analyzed the structure-directing effect of heterologous seeds and surveyed the “common composite building units (CBUs) hypothesis” and the “common secondary building units (SBUs) hypothesis”. However, both hypotheses cannot explain all observations on the heterologous seed-assisted syntheses. Finally, we proposed that the formation of the target zeolite does need nuclei with the structure of target zeolite and the formation of the nuclei of the target zeolite can be promoted by either the undissolved seed crystals with the same CBUs or SBUs to the target zeolite or by the facilitated appropriate distribution of the specific building units due to the presence of the heterologous seed that does not have any common CBUs and SBUs with the target zeolite.
Review articles
Abstract:
Clean and efficient recycling of spent lithium-ion batteries (LIBs) has become an urgent need to promote sustainable and rapid development of human society. Therefore, we provide a critical and comprehensive overview of the various technologies for recycling spent LIBs, starting with lithium-ion power batteries. Recent research on raw material collection, metallurgical recovery, separation and purification is highlighted, particularly in terms of all aspects of economic efficiency, energy consumption, technology transformation and policy management. Mechanisms and pathways for transformative full-component recovery of spent LIBs are explored, revealing a clean and efficient closed-loop recovery mechanism. Optimization methods are proposed for future recycling technologies, with a focus on how future research directions can be industrialized. Ultimately, based on life-cycle assessment, the challenges of future recycling are revealed from the LIBs supply chain and stability of the supply chain of the new energy battery industry to provide an outlook on clean and efficient short process recycling technologies. This work is designed to support the sustainable development of the new energy power industry, to help meet the needs of global decarbonization strategies and to respond to the major needs of industrialized recycling.
Abstract:
Mixed matrix membranes (MMMs) could combine the advantages of both polymeric membranes and porous fillers, making them an effective alternative to conventional polymer membranes. However, interfacial incompatibility issues, such as the presence of interfacial voids, hardening of polymer chains, and blockage of micropores by polymers between common MMMs fillers and the polymer matrix, currently limit the gas separation performance of MMMs. Ternary phase MMMs (consisting of a filler, an additive, and a matrix) made by adding a third compound, usually functionalized additives, can overcome the structural problems of binary phase MMMs and positively impact membrane separation performance. This review introduces the structure and fabrication processes for ternary MMMs, categorizes various nanofillers and the third component, and summarizes and analyzes in detail the CO2 separation performance of newly developed ternary MMMs based on both rubbery and glassy polymers. Based on this separation data, the challenges of ternary MMMs are also discussed. Finally, future directions for ternary MMMs are proposed.
Abstract:
Nowadays, the rapid development of the social economy inevitably leads to global energy and environmental crisis. For this reason, more and more scholars focus on the development of photocatalysis and/or electrocatalysis technology for the advantage in the sustainable production of high-value-added products, and the high efficiency in pollutants remediation. Although there is plenty of outstanding research has been put forward continuously, most of them focuses on catalysis performance and reaction mechanisms in laboratory conditions. Realizing industrial application of photo/electrocatalytic processes is still a challenge that needs to be overcome by social demand. In this regard, this review comprehensively summarized several explorations in the field of photo/electrocatalytic reduction towards potential industrial applications in recent years. Special attention is paid to the successful attempts and the current status of photo/electrocatalytic water splitting, carbon dioxide conversion, resource utilization from waste, etc., by using advanced reactors. The key problems and challenges of photo/electrocatalysis in future industrial practice are also discussed, and the possible development directions are also pointed out from the industry view.
Research papers
Abstract:
To develop emerging electrode materials and improve the performances of batteries, the machine learning techniques can provide insights to discover, design and develop battery new materials in high-throughput way. In this paper, two deep learning models are developed and trained with two feature groups extracted from the Materials Project datasets to predict the battery electrochemical performances including average voltage, specific capacity and specific energy. The deep learning models are trained with the multilayer perceptron as the core. The Bayesian optimization and Monte Carlo methods are applied to improve the prediction accuracy of models. Based on 10 types of ion batteries, the correlation coefficients are maintained above 0.9 compared to DFT calculation results and the mean absolute error of the prediction results for voltages of two models can reach 0.41 V and 0.20 V, respectively. The electrochemical performance prediction times for the two trained models on thousands of batteries are only 72.9 ms and 75.7 ms. Besides, the two deep learning models are applied to approach the screening of emerging electrode materials for sodium-ion and potassium-ion batteries. This work can contribute to a high-throughput computational method to accelerate the rational and fast materials discovery and design.
Abstract:
Graphitic carbon nitride (g-C3N4) is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics significantly restricts its practical applications. Currently, synthesizing highly crystalline g-C3N4 with sufficient surface activities still remains challenging. Herein, different from using alkali molten salts which is commonly reported, we propose an approach for synthesis of highly crystalline g-C3N4 with FeCl3/KCl rock/molten mixed salts. The rock salt can serve as the structure-directing template while molten salt provides the required liquid medium for re-condensation. Intriguingly, the synthesized photocatalyst showed further enhanced crystallinity and improved surface area along with high π→π* excitation compared with crystalline C3N4 prepared from conventional molten-salt methods. These catalytically advantageous features lead to its superior photocatalytic and piezocatalytic activities with a high reactivity for overall water splitting that is not commonly reported for C3N4. This work provides an effective strategy for structural optimization of organic semiconductor based materials and may inspire new ideas for the design of advanced photocatalysts.
Abstract:
The exploitation of high performance redox-active substances is critically important for the development of non-aqueous redox flow batteries. Herein, three tetrathiofulvalene (TTF) derivatives with different substitution groups, namely TTF diethyl ester (TTFDE), TTF tetramethyl ester (TTFTM), and TTF tetraethyl ester (TTFTE), are prepared and their energy storage properties are evaluated. It has been found that the redox potential and solubility of these TTF derivatives in conventional carbonate electrolytes increases with the number of ester groups. The battery with a catholyte of 0.2 mol L-1 of TTFTE delivers a specific capacity of more than 10 Ah L-1 at the current density of 0.5 C with two discharge voltage platforms locating at as high as 3.85 and 3.60 V vs. Li/Li+. Its capacity retention can be improved from 2.34 Ah L-1 to 3.60 Ah L-1 after 100 cycles by the use of an anion exchange membrane to block the crossover of TTF species. The excellent cycling stability of the TIF esters is supported by their well-delocalized electrons, as revealed by the density function theory calculations. Therefore, the introduction of more and larger electron-withdrawing groups is a promising strategy to simultaneously increase the redox-potential and solubility of redox-active materials for non-aqueous redox flow batteries.
Abstract:
Manganese cobaltite (MnCo2O4) is a promising electrode material because of its attractive redox chemistry and excellent charge storage capability. Our previous work demonstrated that the octahedrally-coordinated Mn are prone to react with the hydroxyl ions in alkaline electrolyte upon electrochemical cycling and separates on the surface of spinel to reconstruct into δ-MnO2 nanosheets irreversibly, thus results in a change of the reaction mechanism with K+ ion intercalation. However, the low capacity has greatly limited its practical application. Herein, we found that the tetrahedrally-coordinated Co2+ ions were leached when MnCo2O4 was equilibrated in 1 mol L-1 HCl solution, leading to the formation of layered CoOOH on MnCo2O4 surface which is originated from the covalency competition induced selective breakage of the CoT–O bond in CoT–O–CoO and subsequent rearrangement of free CoO6 octahedra. The as-formed CoOOH is stable upon cycling in alkaline electrolyte, exhibits conversion reaction mechanism with facile proton diffusion and is free of massive structural evolution, thus enables utilization of the bulk electrode material and realizes enhanced specific capacity as well as facilitated charge transfer and ion diffusion. In general, our work not only offers a feasible approach to deliberate modification of MnCo2O4's surface structure, but also provides an in-depth understanding of its charge storage mechanism, which enables rational design of the spinel oxides with promising charge storage properties.
Abstract:
Melamine formaldehyde foam (MFF) generates many poisonous chemicals through the traditional recycling methods for organic resin wastes. Herein, a high MFF degradation ratio of ca. 97 wt.% was achieved under the mild conditions (160 ℃) in a NaOH–H2O system with ammelide and ammeline as the main degradation products. The alkaline solvent had an obvious corrosion effect for MFF, as indicated by scanning electron microscopy (SEM). The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and 13C nuclear magnetic resonance (NMR). Besides, the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins (MUFs). Moreover, the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times. The degradation process generated few harmful pollutants and no pre- or post-treatments were required, which proves its feasibility in the safe removal or recovery of waste MFF.
Abstract:
Non-degradable polymers cause serious environmental pollution problem, such as the widely-used while unrecyclable coatings which significantly affect the overall degradation performance of products. It is imperative and attractive to develop biodegradable functional coatings. Herein, we proposed a novel strategy to successfully prepare biodegradable, thermoplastic and hydrophobic coatings with high transparence and biosafety by weakening the interchain interactions between cellulose chain. The natural cellulose and cinnamic acid were as raw materials. Via reducing the degree of polymerization (DP) of cellulose and regulating the degree of substitution (DS) of cinnamate moiety, the obtained cellulose cinnamate (CC) exhibited not only the thermal flow behavior but also good biodegradability, which solves the conflict between the thermoplasticity and biodegradability in cellulose-based materials. The glass transition temperature (Tg) and thermal flow temperature (Tf) of the CC could be adjusted in a range of 150–200 ℃ and 180–210 ℃, respectively. The CC with DS < 1.2 and DP ≤ 100 degraded more than 60% after an enzyme treatment for 7 days, and degraded more than 80% after a composting treatment for 42 days. Furthermore, CC had no toxicity to human epidermal cells even at a high concentration (0.5 mg mL-1). In addition, CC could be easily fabricated into multifunctional coating with high hydrophobicity, thermal adhesion and high transparence. Therefore, after combining with cellophane and paperboard, CC coating with low DP and DS could be used to prepare fully-biodegradable heat-sealing packaging, art paper, paper cups, paper straws and food packaging boxes.