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Solvent is involved in many wet-chemical synthesis and bottom-up assembly processes. Understanding its influence on the nanotextural formation of the resultant assemblies is essential for the design and control of the properties for targeted applications. With wet chemically reduced graphene oxide (rGO) membranes as a materials platform, this study investigates the solvent effect on nanotexture formation in 2D nanomaterial-based membranes through light scattering and electrochemical characterization. Our finding indicates that the nanotexture of the resultant rGO membrane is largely correlated to the dielectric constant of the solvent. Specifically, solvents with higher dielectric constants yield rGO membranes with more wrinkled, loosely stacked, and less graphitized structures. In contrast, solvents with a lower dielectric constant tend to yield densely stacked structures with larger graphitized domains. Our finding underscores the important role of solvents in wet processing and nanoengineering of 2D nanomaterial-based membranes and provides valuable insights for their controlled synthesis and application.

Assembling two-dimensional (2D) nanomaterials into laminar membranes with a subnanometer (subnm) interlayer spacing provides a material platform for studying a range of nanoconfinement effects and exploring the technological applications related to the transport of electrons, ions and molecules. However, the strong tendency for 2D nanomaterials to restack to their bulk crystalline-like structure makes it challenging to control their spacing at the subnm scale. It is thus necessary to understand what nanotextures can be formed at the subnm scale and how they can be engineered experimentally. In this work, with dense reduced graphene oxide membranes as a model system, we combine synchrotron-based X-ray scattering and ionic electrosorption analysis to reveal that their subnanometric stacking can result in a hybrid nanostructure of subnm channels and graphitized clusters. We demonstrate that the ratio of these two structural units, their sizes and connectivity can be engineered by stacking kinetics through the reduction temperature to allow the realization of high-performance compact capacitive energy storage. This work highlights the great complexity of subnm stacking of 2D nanomaterials and provides potential methods to engineer their nanotextures at will.

The purpose of the chapter is to investigate the “state of the art” on sustainability reporting, in South Africa. Such country represents a worldwide unicum as a consequence of the publication and adoption of the King Reports that significantly improved corporate social responsibility (CSR) disclosure practices. The research stream was explored by a systematic literature review (Tranfield et al. 2003) and a bibliometric analysis (Zupic and Čater 2015). In particular, a specific focus is on the King III Report, as antecedent for refining the disclosure of CSR issues. In 1994, the first report (King I Report) was released by the “King Committee on Corporate Governance.” The main novelty resided in the relevance of both financial and nonfinancial views.

Single‐atom catalysts (SACs) show high catalytic efficiency in accelerating conversion of lithium polysulfides (LiPS), and are thus promising for suppressing the shuttle effect observed in lithium−sulfur batteries (LSBs); however, single‐atom catalytic sites with low content of catalysts largely restrict their catalytic effect. Herein, a CoP cluster supported by a N‐doped carbon matrix (CoP cluster/NC) with atomic‐level dispersion and an ultrahigh content (25.5 wt.%) of Co atoms is fabricated via an in situ low‐temperature phosphorization strategy and employed as a dual‐atom‐site catalyst for catalyzing LiPS conversion. The CoP cluster/NC with abundant unsaturated CoP coordination provides dual‐atom sites of Co and P to dynamically adsorb/desorb sulfur species and Li+ ions, respectively, synergistically promoting the conversion of LiPS. The dual‐atom‐site catalytic mechanism is evidenced by substantial characterizations including X‐ray absorption fine structure measurements and density functional theory calculations. Consequently, the S@CoP cluster/NC cathode shows superior cycling and rate performance. Even at a high sulfur loading of 6.2 mg cm−2, a high areal capacity of 6.5 mAh cm−2 that surpasses most commercial lithium–ion batteries can be achieved. This study opens a new avenue in the development of advanced catalysts with new catalytic mechanisms for high‐performance LSBs.

Densely assembled graphene‐based membranes have attracted substantial interest for their widespread applications, such as compact capacitive energy storage, ion/molecular separation, gas barrier films, and flexible electronics. However, the multiscale structure of densely packed graphene membranes remains ambiguously understood. This article combines X‐ray and light scattering techniques as well as dynamic electrosorption analysis to uncover the stacking structure of the densely stacked reduced graphene oxide (rGO) membranes. The membranes are produced by reducing graphene oxide (GO) membranes with hydrazine, during which the colloidal interactions between GO sheets are modulated by the electrolyte solution. In contrast to the common notion that direct reduction of densely assembled GO sheets in parallel tends to result in significant “graphitization”, this article unexpectedly discovers that the resultant densely packed rGO membrane can still retain the interconnected network nanochannels and show good capacitive performances. This inspires the development of a hierarchical structural model to describe the densely packed rGO membranes. This article further shows that the nanochannel network can be fine‐tuned at the sub‐nanometer level by tailoring the salt concentration and the reduction temperature to render exceptional volumetric capacitance and good rate performance for rGO membranes even with increased packing density.

Densely assembled graphene-based membranes have attracted substantial interest for their widespread applications, such as compact capacitive energy storage, ion/molecular separation, gas barrier films, and flexible electronics. However, the multiscale structure of densely packed graphene membranes remains ambiguously understood. This article combines X-ray and light scattering techniques as well as dynamic electrosorption analysis to uncover the stacking structure of the densely stacked reduced graphene oxide (rGO) membranes. The membranes are produced by reducing graphene oxide (GO) membranes with hydrazine, during which the colloidal interactions between GO sheets are modulated by the electrolyte solution. In contrast to the common notion that direct reduction of densely assembled GO sheets in parallel tends to result in significant “graphitization”, this article unexpectedly discovers that the resultant densely packed rGO membrane can still retain the interconnected network nanochannels and show good capacitive performances. This inspires the development of a hierarchical structural model to describe the densely packed rGO membranes. This article further shows that the nanochannel network can be fine-tuned at the sub-nanometer level by tailoring the salt concentration and the reduction temperature to render exceptional volumetric capacitance and good rate performance for rGO membranes even with increased packing density.

Developing zero-strain electrode materials with high capacity is crucial for lithium-ion batteries (LIBs). Here, a new zero-strain composite material made of ultrasmall Si nanodots (NDs) within metal organic framework-derived nanoreactors (Si NDs⊂MDN) through a novel space-confined catalytic strategy is reported. The unique Si NDs⊂MDN anode features a low strain (<3%) and a high theoretical lithium storage capacity (1524 mAh g-1 ) which far surpasses the traditional single-crystal counterparts that suffer from a low capacity delivery. The zero-strain property is evidenced by substantial characterizations including ex/in situ transmission electron microscopy and mechanical simulations. The Si NDs⊂MDN exhibits superior cycling stability and high reversible capacity (1327 mAh g-1 at 0.1 A g-1 after 100 cycles) in half-cells and high energy density (366 Wh kg-1 after 300 cycles) in a full cell. This study reports a new catalog of zero-strain electrode material with significantly improved capacity beyond the traditional single-crystal zero-strain materials.

The exploration of ideal electrode materials overcoming the critical problems of large electrode volume changes and sluggish redox kinetics induced by large ionic radius of Na+ /K+ ions is highly desirable for sodium/potassium-ion batteries (SIBs/PIBs) toward large-scale applications. The present work demonstrates that single-phase ternary cobalt phosphoselenide (CoPSe) in the form of nanoparticles embedded in a layered metal-organic framework (MOF)-derived N-doped carbon matrix (CoPSe/NC) represents an ultrastable and high-rate anode material for SIBs/PIBs. The CoPSe/NC is fabricated by using the MOF as both a template and precursor, coupled with in situ synchronous phosphorization/selenization reactions. The CoPSe anode holds a set of intrinsic merits such as lower mechanical stress, enhanced reaction kinetics, as well as higher theoretical capacity and lower discharge voltage relative to its counterpart of CoSe2 , and suppressed shuttle effect with higher intrinsic electrical conductivity relative to CoPS. The involved mechanisms are evidenced by substantial characterizations and density functional theory (DFT) calculations. Consequently, the CoPSe/NC anode shows an outstanding long-cycle stability and rate performance for SIBs and PIBs. Moreover, the CoPSe/NC-based Na-ion full cell can achieve a higher energy density of 274 Wh kg-1 , surpassing that based on CoSe2 /NC and most state-of-the-art Na-ion full cells based on P-, Se-, or S-containing binary/ternary anodes to date.

The photocatalytic properties of TiO2 have aroused a broad range of research interest since 1972 due to its abundance, chemical stability, and easily available nature. To increase its overall activity, in the past few decades, much effort has been devoted to the fabrication of advanced TiO2‐based photocatalysts with visible‐light response and these photocatalysts have shown great potential in the field of solar energy utilization. Here, recent progress in the investigation of visible‐light responsive TiO2‐based materials are reviewed. Notably, the fabrication strategies and corresponding chemical/physical properties of visible‐light responsive TiO2‐based materials are described in detail, with a focus on bandgap engineering and junction engineering from the perspective of light absorption, charge transfer and separation, and surface reactions. Their applications in solar‐fuel production, organic synthesis, bacterial disinfection, pollutant degradation and nitrogen fixation are also discussed. Moreover, the new trends and ongoing challenges in this field are proposed and highlighted.

Thin-film composite (TFC) polymeric membranes have attracted increasing interest to meet the demands of industrial gas separation. However, the development of high-performance TFC membranes within their current configuration faces two key challenges: (i) the thickness-dependent gas permeability of polymeric materials (mainly poly(dimethylsiloxane) (PDMS)) and (ii) the geometric restriction effect due to the limited pore accessibility of the underlying porous substrate. Here we demonstrate that the incorporation of trace amounts (∼1.8 wt %) of amorphous metal-organic framework (MOF) nanosheets into the gutter layer of TFC assemblies can simultaneously address these two limitations by the creation of rapid, transmembrane gas diffusion pathways. The resultant PDMS&MOF membrane displayed excellent CO2 permeance of 10450 GPU and CO2/N2 selectivity of 9.1. Leveraging this strategy, we successfully fabricate a novel TFC membrane, consisting of a PDMS&MOF gutter and an ultrathin (∼54 nm) poly(ethylene glycol) top selective layer via surface-initiated atom transfer radical polymerization. The complete TFC membrane exhibits excellent processability and remarkable CO2/N2 separation performance (1990 GPU with a CO2/N2 ideal selectivity of 39). This study reveals a strategy for the design and fabrication of a new TFC membrane system with unprecedented gas-separation performance.

Transition metal-based nanomaterials represent an emerging class of highly active and low-cost precatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, most OER precatalysts undergo slow or incomplete self-reconstructions to generate real active sites, which is a time-consuming process for achieving high OER performance. Thus, we report a new class of OER precatalysts that can achieve highly active OER species by a rapid and deep self-reconstruction (denoted by SELF-RECON). The precatalysts with a core-shell structure comprising NiMoO4 (core) and NiFe/NiFeOx nanoparticles in N-doped amorphous carbons (shell) (denoted by NiMoFeO@NC), can realize rapid MoO42− dissolution and fast formation of NiOOH with Fe incorporation simultaneously. In situ Raman spectroscopy together with electron microscopy, X-ray photoelectron spectroscopy, and electrochemical tests indicate that the obtained NiFeOOH/NiFe-LDH after SELF-RECON behave as the real active species that outperform NiMoFeO@NC, with ultralow overpotentials and extraordinary long-term stability.

Summary Effective design of bifunctional catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is important but remains challenging. Herein, we report a three-dimensional (3D) hierarchical structure composed of homogeneously distributed Ni-Fe-P nanoparticles embedded in N-doped carbons on nickel foams (denoted as Ni-Fe-P@NC/NF) as an excellent bifunctional catalyst. This catalyst was fabricated by an anion exchange method and a low-temperature phosphidation of nanotubular Prussian blue analogue (PBA). The Ni-Fe-P@NC/NF displayed exceptional catalytic activity toward both HER and OER and delivered an ultralow cell voltage of 1.47 V to obtain 10 mA cm−2 with extremely excellent durability for 100 h when assembled as a practical electrolyser. The extraordinary performance of Ni-Fe-P@NC/NF is attributed to the abundance of unsaturated active sites, the well-defined hierarchical porous structure, and the synergistic effect between multiple components. Our work will inspire more rational designs of highly active non-noble electrocatalysts for industrial energy applications.

Silicon nanoparticles (Si NPs) have been considered as promising anode materials for next‐generation lithium‐ion batteries, but the practical issues such as mechanical structure instability and low volumetric energy density limit their development. At present, the functional energy‐storing architectures based on Si NPs building blocks have been proposed to solve the adverse effects of nanostructures, but designing ideal functional architectures with excellent electrochemical performance is still a significant challenge. This study shows that the effective stress evolution management is applied for self‐assembled functional architectures via cross‐scale simulation and the simulated stress evolution can be a guide to design a scalable self‐assembled hierarchical Si@TiO2@C (SA‐SiTC) based on core–shell Si@TiO2 nanoscale building blocks. It is found that the carbon filler and TiO2 layer can effectively reduce the risk of cracking during (de)lithiation, ensuring the stability of the mechanical structure of SA‐SiTC. The SA‐SiTC electrode shows long cycling stability (842.6 mAh g−1 after 1000 cycles at 2 A g−1), high volumetric capacity (174 mAh cm−3), high initial Coulombic efficiency (80.9%), and stable solid‐electrolyte interphase (SEI) layer. This work provides insight into the development of the structural stable Si‐based anodes with long cycle life and high volumetric energy density for practical energy applications.

Incorporating nanoscale Si into a carbon matrix with high dispersity is desirable for the preparation of lithium-ion batteries (LIBs) but remains challenging. A space-confined catalytic strategy is proposed for direct superassembly of Si nanodots within a carbon (Si NDs⊂C) framework by copyrolysis of triphenyltin hydride (TPT) and diphenylsilane (DPS), where Sn atomic clusters created from TPT pyrolysis serve as the catalyst for DPS pyrolysis and Si catalytic growth. The use of Sn atomic cluster catalysts alters the reaction pathway to avoid SiC generation and enable formation of Si NDs with reduced dimensions. A typical Si NDs⊂C framework demonstrates a remarkable comprehensive performance comparable to other Si-based high-performance half LIBs, and higher energy densities compared to commercial full LIBs, as a consequence of the high dispersity of Si NDs with low lithiation stress. Supported by mechanic simulations, this study paves the way for construction of Si/C composites suitable for applications in future energy technologies.

Developing high‐performance electrode materials is an urgent requirement for next‐generation energy conversion and storage systems. Due to the exceptional features, mesoporous materials have shown great potential to achieve high‐performance electrodes with high energy/power density, long lifetime, increased interfacial reaction activity, and enhanced kinetics. In this Essay, applications of mesoporous materials are reviewed in electrochemical energy conversion and storage devices. The synthesis, structure, and properties of mesoporous materials and their performance in rechargeable batteries, supercapacitors, fuel cells, and electrolyzers are discussed, providing practical details and enlightening comments on the construction of high‐performance mesoporous electrodes. Lastly, the research challenges and perspectives on mesoporous materials for the future development of energy conversion and storage devices are assessed.

Weak van der Waals interactions between interlayers of two-dimensional layered materials result in disabled across-interlayer electron transfer and poor layered structural stability, seriously deteriorating their performance in energy applications. Herein, we propose a novel covalent assembly strategy for MoS2 nanosheets to realize unique MoS2 /SnS hollow superassemblies (HSs) by using SnS nanodots as covalent linkages. The covalent assembly based on all-inorganic and carbon-free concept enables effective across-interlayer electron transfer, facilitated ion diffusion kinetics, and outstanding mechanical stability, which are evidenced by experimental characterization, DFT calculations, and mechanical simulations. Consequently, the MoS2 /SnS HSs exhibit superb rate performance and long cycling stability in lithium-ion batteries, representing the best comprehensive performance in carbon-free MoS2 -based anodes to date. Moreover, the MoS2 /SnS HSs also show excellent sodium storage performance in sodium-ion batteries.

The intercalation strategy has become crucial for 2D layered materials to achieve desirable properties, however, the intercalated guests are often limited to metal ions or small molecules. Here, we develop a simple, mild and efficient polymer-direct-intercalation strategy that different polymers (polyethyleneimine and polyethylene glycol) can directly intercalate into the MoS2 interlayers, forming MoS2-polymer composites and interlayer-expanded MoS2/carbon heteroaerogels after carbonization. The polymer-direct-intercalation behavior has been investigated by substantial characterizations and molecular dynamic calculations. The resulting composite heteroaerogels possess 3D conductive MoS2/C frameworks, expanded MoS2 interlayers (0.98 nm), high MoS2 contents (up to 74%) and high Mo valence (+6), beneficial to fast and stable charge transport and enhanced pseudocapacitive energy storage. Consequently, the typical MoS2/N-doped carbon heteroaerogels exhibit outstanding supercapacitor performance, such as ultrahigh capacitance, remarkable rate capability and excellent cycling stability. This study offers a new intercalation strategy which may be generally applicable to 2D materials for promising energy applications.

Transition metal oxides/carbon (TMOs/C) composites are important for high-performance lithium-ion batteries (LIBs), but the development of interface-stable TMOs/C composite anodes for robust lithium storage is still a challenge. Herein, mesoporous TiO2/TiC@C composite membranes were synthesized by an in situ carbothermic reduction method. TiC nanodots with high conductivity and electrochemical inactivity at the TiO2-C interface can significantly enhance the electrical conductivity and structural stability of the membranes. Finite element simulations demonstrate that the TiO2/TiC@C membranes can effectively alleviate tensile and compression stress effects upon lithiation, which is beneficial for robust lithium storage. When used as additives and binder-free electrodes, the TiO2/TiC@C membranes show excellent cycling capability and rate performance. Moreover, a flexible full battery can be assembled by employing the TiO2/TiC@C membranes and shows good performance, highlighting the potential of these membranes in flexible electronics. This work opens an avenue to constructing interface-stable composite structures for the next-generation high-performance LIBs.

The realization of antipulverization electrode structures, especially using low-carbon-content anode materials, is crucial for developing high-energy and long-life lithium-ion batteries (LIBs); however, this technology remains challenging. This study shows that SnO2 triple-shelled hollow superstructures (TSHSs) with a low carbon content (4.83%) constructed by layer-by-layer assembly of various nanostructure units can withstand a huge volume expansion of ≈231.8% and deliver a high reversible capacity of 1099 mAh g-1 even after 1450 cycles. These values represent the best comprehensive performance in SnO2 -based anodes to date. Mechanics simulations and in situ transmission electron microscopy suggest that the TSHSs enable a self-synergistic structure-preservation behavior upon lithiation/delithiation, protecting the superstructures from collapse and guaranteeing the electrode structural integrity during long-term cycling. Specifically, the outer shells during lithiation processes are fully lithiated, preventing the overlithiation and the collapse of the inner shells; in turn, in delithiation processes, the underlithiated inner shells work as robust cores to support the huge volume contraction of the outer shells; meanwhile, the middle shells with abundant pores offer sufficient space to accommodate the volume change from the outer shell during both lithiation and delithiation. This study opens a new avenue in the development of high-performance LIBs for practical energy applications.