Institute of Process Engineering

A comprehensive database on physical properties of ionic liquids (ILs), which was collected from 109 kinds of literature sources in the period from 1984 through 2004, has been presented. There are 1680 pieces of data on the physical properties for 588 available ILs, from which 276 kinds of cations and 55 kinds of anions were extracted. In terms of the collected database, the structure-property relationship was evaluated. The correlation of melting points of two most common systems, disubstituted imidazolium tetrafluoroborate and disubstituted imidazolium hexafluorophosphate, was carried out using a quantitative structure-property relationship method.

Recycling of spent lithium-ion batteries (LIBs) has attracted significant attention in recent years due to the increasing demand for corresponding critical metals/materials and growing pressure on the environmental impact of solid waste disposal. A range of investigations have been carried out for recycling spent LIBs to obtain either battery materials or individual compounds. For the effective recovery of materials to be enhanced, physical pretreatment is usually applied to obtain different streams of waste materials ensuring efficient separation for further processing. Subsequently, a metallurgical process is used to extract metals or separate impurities from a specific waste stream so that the recycled materials or compounds can be further prepared by incorporating principles of materials engineering. In this review, the current status of spent LIB recycling is summarized in light of the whole recycling process, especially focusing on the hydrometallurgy. In addition to understanding different hydrometallurgical technologies including acidic leaching, alkaline leaching, chemical precipitation, and solvent extraction, the existing challenges for process optimization during the recycling are critically analyzed. Moreover, the energy consumption of different processes is evaluated and discussed. It is expected that this research could provide a guideline for improving spent LIB recycling, and this topic can be further stimulated for industrial realization.

Hollow micro-/nano-structured materials are now playing an important role in cutting edge innovations for energy conversion and storage technologies such as solar cells, fuel cells, lithium ion batteries and super capacitors. These materials show great promise in addressing growing environmental concerns for cleaner power sources at a time of increasing global demand for energy. In this perspective, we show that complex multi-shelled micro-/nano-materials show significant material advantages in many applications over conventional simple hollow structures. We also summarize the vast array of synthetic strategies used to create multi-shelled hollow structures, and discuss the possible application of these novel materials for power generation and storage. Finally, the emergent challenges and future developments of multi-shelled hollow structures are further discussed.

Abstract High-entropy ceramics (HECs) are solid solutions of inorganic compounds with one or more Wyckoff sites shared by equal or near-equal atomic ratios of multi-principal elements. Although in the infant stage, the emerging of this new family of materials has brought new opportunities for material design and property tailoring. Distinct from metals, the diversity in crystal structure and electronic structure of ceramics provides huge space for properties tuning through band structure engineering and phonon engineering. Aside from strengthening, hardening, and low thermal conductivity that have already been found in high-entropy alloys, new properties like colossal dielectric constant, super ionic conductivity, severe anisotropic thermal expansion coefficient, strong electromagnetic wave absorption, etc., have been discovered in HECs. As a response to the rapid development in this nascent field, this article gives a comprehensive review on the structure features, theoretical methods for stability and property prediction, processing routes, novel properties, and prospective applications of HECs. The challenges on processing, characterization, and property predictions are also emphasized. Finally, future directions for new material exploration, novel processing, fundamental understanding, in-depth characterization, and database assessments are given.

Self-assembling systems play a significant role in physiological functions and have therefore attracted tremendous attention due to their great potential for applications in energy, biomedicine and nanotechnology. Peptides, consisting of amino acids, are among the most popular building blocks and programmable molecular motifs. Nanostructures and materials assembled using peptides exhibit important potential for green-life new technology and biomedical applications mostly because of their bio-friendliness and reversibility. The formation of these ordered nanostructures pertains to the synergistic effect of various intermolecular non-covalent interactions, including hydrogen-bonding, π-π stacking, electrostatic, hydrophobic, and van der Waals interactions. Therefore, the self-assembly process is mainly driven by thermodynamics; however, kinetics is also a critical factor in structural modulation and function integration. In this review, we focus on the influence of thermodynamic and kinetic factors on structural assembly and regulation based on different types of peptide building blocks, including aromatic dipeptides, amphiphilic peptides, polypeptides, and amyloid-relevant peptides.

The inherent structure tunability, good affinity with CO2, and nonvolatility of ionic liquids (ILs) drive their exploration and exploitation in CO2 separation field, and has attracted remarkable interest from both industries and academia. The aim of this Review is to give a detailed overview on the recent advances on IL-based materials, including pure ILs, IL-based solvents, and IL-based membranes for CO2 capture and separation from the viewpoint of molecule to engineering. The effects of anions, cations and functional groups on CO2 solubility and selectivity of ILs, as well as the studies on degradability of ILs are reviewed, and the recent developments on functionalized ILs, IL-based solvents, and IL-based membranes are also discussed. CO2 separation mechanism with IL-based solvents and IL-based membranes are explained by combining molecular simulation and experimental characterization. Taking into consideration of the applications and industrialization, the recent achievements and developments on the transport properties of IL fluids and the process design of IL-based processes are highlighted. Finally, the future research challenges and perspectives of the commercialization of CO2 capture and separation with IL-based materials are posed.

As a novel two-dimensional (2D) material, graphene shows great benefits in electric and material science. Compared to 1D nanomaterials, it may show more excellent properties. Here, we introduced graphene as 2D bridges into the nanocrystalline electrodes of dye-sensitized solar cells, which brought a faster electron transport and a lower recombination, together with a higher light scattering. On the basis of these advantages, the short-circuit current density was increased by 45% without sacrificing the open-circuit voltage, and the total conversion efficiency was 6.97%, which was increased by 39%, comparing with the nanocrystalline titanium dioxide photoanode, and it was also much better than the 1D nanomaterial composite electrode.

Photothermal agents can harvest light energy and convert it into heat, offering a targeted and remote-controlled way to destroy carcinomatous cells and tissues. Inspired by the biological organization of polypeptides and porphyrins in living systems, here we have developed a supramolecular strategy to fabricate photothermal nanodots through peptide-modulated self-assembly of photoactive porphyrins. The self-assembling nature of porphyrins induces the formation of J-aggregates as substructures of the nanodots, and thus enables the fabrication of nanodots with totally inhibited fluorescence emission and singlet oxygen production, leading to a high light-to-heat conversion efficiency of the nanodots. The peptide moieties not only provide aqueous stability for the nanodots through hydrophilic interactions, but also provide a spatial barrier between porphyrin groups to inhibit the further growth of nanodots through the strong π-stacking interactions. Thermographic imaging reveals that the conversion of light to heat based on the nanodots is efficient in vitro and in vivo, enabling the nanodots to be applied for photothermal acoustic imaging and antitumor therapy. Antitumor therapy results show that these nanodots are highly biocompatible photothermal agents for tumor ablation, demonstrating the feasibility of using bioinspired nanostructures of self-assembling biomaterials for biomedical photoactive applications.

We report the largely improved electrochemical capacitance of polypyrrole-derived microporous carbon nanospheres (MCNs, 80–100 nm in diameter) containing nitrogen functional groups. We have investigated the electrochemical properties of precursor polypyrrole nanospheres (PNs, with a high N/C ratio and low surface area) and as-derived carbon nanospheres (CNs, with a moderate N/C ratio and low surface area) prepared by carbonizing PNs at different temperatures, and MCNs (with a low N/C ratio and high surface area) obtained by chemical activation of CNs. The samples are thoroughly characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), nitrogen sorption, elemental analysis, and X-ray photoelectron spectroscopy (XPS). It is found that MCNs with a high surface area and N-doping species exhibit much better capacitive performance compared to the PNs and CNs, and commercial carbon blacks (XC-72 and BP2000) as well. The MCN sample gives a reversible specific capacitance of ∼240 F g−1 for 3000 cycles in aqueous media as a result of combined advantages of high electrochemical activity of doped heteroatoms (N and O) and accessible well-developed porosity, demonstrating the promising use in high-energy-density supercapacitors.

Graphdiyne (GDY), a new two-dimensional (2D) carbon allotrope, has been receiving increased attention. Its unique sp-sp2 carbon atoms, uniform pores, and highly π-conjugated structure provide promising potential in practical applications, such as gas separation, catalysis, water remediation, humidity sensor, and energy-related fields. In the recent years, considerable efforts have been expended toward the development of well-defined GDY. However, GDY materials still face numerous challenges, including the need for a more thorough understanding of the growth mechanism, strategies for synthesizing one- or few-layer single-crystalline GDY films, characterization of basic physicochemical properties, and achievement of promising applications. This review aims at providing a comprehensive update on the synthesis of GDY and GDY-based materials, as well as their properties, including structural, electronic, mechanical, and spectral properties, and their applications in nanotechnology.

Synthetic natural gas (SNG) can be obtained via methanation of synthesis gas (syngas). Many thermodynamic reaction details involved in this process are not yet fully understood. In this paper, a comprehensive thermodynamic analysis of reactions occurring in the methanation of carbon oxides (CO and CO2) is conducted using the Gibbs free energy minimization method. The equilibrium constants of eight reactions involved in the methanation reactions were calculated at different temperatures. The effects of temperature, pressure, ratio of H2/CO (and H2/CO2), and the addition of other compounds (H2O, O2, CH4, and C2H4) in the feed gas (syngas) on the conversion of CO and CO2, CH4 selectivity and yield, as well as carbon deposition, were carefully investigated. In addition, experimental data obtained on commercial Ni-based catalysts for CO methanation and three cases adopted from the literature were compared with the thermodynamic calculations. It is found that low temperature, high pressure, and a large H2/CO (and H2/CO2) ratio are favourable for the methanation reactions. Adding steam into the feed gas could alleviate the carbon deposition to a large extent. Trace amounts of O2 in syngas is unfavourable for SNG generation although it can lower carbon deposition. Additional CH4 in the feed gas almost has no influence on the CO conversion and CH4 yield, but it leads to the increase of carbon formed. Introduction of a small amount of C2H4, a representative of hydrocarbons in syngas, results in low CH4 yield and serious carbon deposition although it does not affect CO conversion. CO is relatively easy to hydrogenated compared to CO2 at the same reaction conditions. The comparison of thermodynamic calculations with experimental results demonstrated that the Gibbs free energy minimization method is significantly effective for understanding the reactions occurring in methanation and helpful for the development of catalysts and processes for the production of SNG.

As an emerging carbon dioxide (CO2) capture technology, separating CO2 from industrial gases with ionic liquids is increasingly attracting remarkable interests. In this paper, the research progress on CO2 capture with ionic liquids is reviewed with particular attention on the viewpoint of potential industrial applications. We investigate and compare the CO2 capture capacities of pure ionic liquids, including conventional and task-specific ionic liquids, and ionic liquid-based mixtures. The mechanisms of chemisorption and physisorption are explained with experimental characteristics and molecular simulation, which show more and more important roles for screening suitable ionic liquids from tremendous candidates. Considering the scaling up of novel units for ionic liquid-based fluids, the studies on the transport properties and hydrodynamics of ionic liquid fluids are presented. The process design and assessment of ionic liquid processes are discussed, including the research progress on thermodynamic properties and prediction models. Besides giving an overview of research for each issue above, we also provide discussions for future work to try to identify the gap between the current work and the demand by real industrial applications. Finally, we present some perspectives of ionic liquid-based novel technologies, and the challenges which will be faced while developing industrially available technologies.

In recent years, emulsions stabilized by micro- or nanoparticles (known as Pickering emulsions) have attracted much attention. Micro- or nanoparticles, as the main components of the emulsion, play a key role in the preparation and application of Pickering emulsions. The existence of particles at the interface between the oil and aqueous phases affects not only the preparation, but also the properties of Pickering emulsions, affording superior stability, low toxicity, and stimuli-responsiveness compared to classical emulsions stabilized by surfactants. These advantages of Pickering emulsions make them attractive, especially in biomedicine. In this review, the effects of the characteristics of micro- and nanoparticles on the preparation and properties of Pickering emulsions are introduced. In particular, the preparation methods of Pickering emulsions, especially uniform-sized emulsions, are listed. Uniform Pickering emulsions are convenient for both mechanistic research and applications. Furthermore, some biomedical applications of Pickering emulsions are discussed and the problems hindering their clinical application are identified.

Self-healing coatings inspired by biological systems possess the ability to repair physical damage or recover functional performance with minimal or no intervention. This article provides a comprehensive and updated review on the advantages and limitations associated with common autonomous and non-autonomous self-healing mechanisms in protective organic coatings used for anti-corrosion purposes. The autonomous healing mechanisms are often enabled by embedding polymerizable healing agents or corrosion inhibitors in the coating matrices. For non-autonomous mechanisms, the healing effects are induced by external heat or light stimuli, which trigger the chemical reactions or physical transitions necessary for bond formation or molecular chain movement.

An injectable and self-healing collagen–gold hybrid hydrogel is spontaneously formed by electrostatic self-assembly and subsequent biomineralization. It is demonstrated that such collagen-based hydrogels may be used as an injectable material for local delivery of therapeutic agents, showing enhanced antitumor efficacy. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The rapid growth of lithium ion batteries (LIBs) for portable electronic devices and electric vehicles has resulted in an increased number of spent LIBs. Spent LIBs contain not only dangerous heavy metals but also toxic chemicals that pose a serious threat to ecosystems and human health. Therefore, a great deal of attention has been paid to the development of an efficient process to recycle spent LIBs for both economic aspects and environmental protection. In this paper, we review the state-of-the-art processes for metal recycling from spent LIBs, introduce the structure of a LIB, and summarize all available technologies that are used in different recovery processes. It is notable that metal extraction and pretreatment play important roles in the whole recovery process, based on one or more of the principles of pyrometallurgy, hydrometallurgy, biometallurgy, and so forth. By further comparing different recycling methods, existing challenges are identified and suggestions for improving the recycling effectiveness can be proposed.

This review provides a comprehensive assessment of recently improved carbon dioxide (CO2) separation and capture systems, used in power plants and other industrial processes. Different approaches for CO2 capture are pre-combustion, post-combustion capture, and oxy-combustion systems, which are reviewed, along with their advantages and disadvantages. New technologies and prospective “breakthrough technologies”, for instance: novel solvents, sorbents, and membranes for gas separation are examined. Other technologies including chemical looping technology (reaction between metal oxides and fuels, creating metal particles, carbon dioxide, and water vapor) and cryogenic separation processes (based on different phase change temperatures for various gases to separate them) are reviewed as well. Furthermore, the major CO2 separation technologies, such as absorption (using a liquid solvent to absorb the CO2), adsorption (using solid materials with surface affinity to CO2 molecules), and membranes (using a thin film to selectively permeate gases) are extensively discussed, though issues and technologies related to CO2 transport and storage are not considered in this paper.

More than just an empty shell: Multishelled Co3O4 microspheres were synthesized as anode materials for lithium-ion batteries in high yield and purity. As their porous hollow multishell structure guarantees a shorter Li+ diffusion length and sufficient void space to buffer the volume expansion, their rate capacity, cycling performance, and specific capacity were excellent (1615.8 mA h g−1 in the 30th cycle for triple-shelled Co3O4; see graph). As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Ionic liquids (ILs) offer a wide range of promising applications because of their much enhanced properties. However, further development of such materials depends on the fundamental understanding of their hierarchical structures and behaviors, which requires multiscale strategies to provide coupling among various length scales. In this review, we first introduce the structures and properties of these typical ILs. Then, we introduce the multiscale modeling methods that have been applied to the ILs, covering from molecular scale (QM/MM), to mesoscale (CG, DPD), to macroscale (CFD for unit scale and thermodynamics COSMO-RS model and environmental assessment GD method for process scale). In the following section, we discuss in some detail their applications to the four scales of ILs, including molecular scale structures, mesoscale aggregates and dynamics, and unit scale reactor design and process design and optimization of typical IL applications. Finally, we address the concluding remarks of multiscale strategies in the understanding and predictive capabilities of ILs. The present review aims to summarize the recent advances in the fundamental and application understanding of ILs.

Hierarchically ordered macro-mesoporous titania films have been produced through a confinement self-assembly method within the regular voids of a colloidal crystal with three-dimensional periodicity. Furthermore, graphene as an excellent electron-accepting and electron-transporting material has been incorporated into the hierarchically ordered macro-mesoporous titania frameworks by in situ reduction of graphene oxide added in the self-assembly system. Incorporation of interconnected macropores in mesoporous films improves the mass transport through the film, reduces the length of the mesopore channel, and increases the accessible surface area of the thin film, whereas the introduction of graphene effectively suppresses the charge recombination. Therefore, the significant enhancement of photocatalytic activity for degrading the methyl blue has been achieved. The apparent rate constants for macro-mesoporous titania films without and with graphene are up to 0.045 and 0.071 min(-1), respectively, almost 11 and 17 times higher than that for pure mesoporous titania films (0.0041 min(-1)).