From Layered Crystals to Permselective Membranes: History, Fundamentals, and Opportunities.

Membranes are crucial in permselective processes, such as water purification, gas sequestration, ion separation, membrane distillation and pervaporation, and energy conversion and storage. The two-decade development of two-dimensional (2D) membranes has shifted the membrane transport from solution-diffusion in the polymer matrix to size-dependent migration in Ångström-to-nanoscale slit-like channels, delivering distinctive fundamentals within nanoconfinements and potential implementations. In this review, we delve into the comprehensive information that facilitates the transformation of layered crystals into continuous thin-film architectures boasting well-defined nanopores.

Self-Trapped Excitons Activate Pseudo-Inert Basal Planes of 2D Organic Semiconductors for Improved Photocatalysis.

2D organic semiconductors are widely considered superior photocatalysts due to their large basal planes, which host abundant and tunable reaction sites. However, here, it is discovered that these basal planes can be pseudo-inert, fundamentally challenging conventional design strategies that assume uniform activity on the surface of 2D organic semiconductors. Using 2D potassium-poly (heptazine imide) (KPHI) for hydrogen peroxide photocatalysis as a model, it is demonstrated that the pseudo-inertness of basal planes stems from preferential exciton transport to edges, instead of interlayer transport in highly ordered structures.

Water Oxidation to Hydrogen Peroxide Over a Super-Aerophilic Graphite Catalyst.

Two-electron water oxidation reaction (2e-WOR) to produce hydrogen peroxide (HO) is an attractive anode reaction with several merits. It can be paired with several large-scale cathode reactions that produce valuable chemical substances in an electrochemical cell. However, high-performing and reliable 2e-WOR anodic catalysts are yet to be fully developed.

Regulate Ion Transport in Subnanochannel Membranes by Ion-Pairing.

The ability of biological ion channels to respond to environmental stimuli, regulate ion permeation rates, and selectively transport specific ions is essential for sustaining physiological functions and holds immense potential for various practical applications. In this study, we report a highly selective ion separation membrane capable of responding to ionic stimuli, thereby regulating the permeation rate of the target ions. This membrane is constructed from two-dimensional MXene nanosheets functionalized with γ-poly(glutamic acid) (γ-PGA) molecules.

Breaking the trade-off between lithium purity and lithium recovery: A comprehensive mathematical modeling based on membrane structure-property-performance relationships.

The application of nanofiltration (NF) membranes for resource recovery, particularly lithium (Li) extraction from high magnesium (Mg) brines, is a rapidly growing research area. However, the trade-off between high Li purity and recovery remains challenging. In our study, we extend the widely adopted Donnan Steric Pore Model with Dielectric Exclusion (DSPM-DE) to analyze membrane structure-property-performance relationships at the process scale.

Material needs for power-to-X systems for CO utilization require a life cycle approach.

The world's transition from a fossil-fuel-driven society to a future net-zero or negative carbon dioxide emission society will require a significant scale-up of Power-to-X technologies to capture and convert CO to low carbon intensity fuels and chemicals. The deployment of Power-to-X technologies at gigawatt scales necessary to impact CO emissions and replace existing fossil-fuel-dependent processes will require vast quantities of raw materials and minerals. Many of the materials required in Power-to-X systems, such as rare earth metal yttrium and iridium, differ from those used to construct and operate petroleum-hydrocarbon-based processes for the last 100 years.

Nanoconfinement Effects in Electrocatalysis and Photocatalysis.

Recently, the enzyme-inspired nanoconfinement effect has garnered significant attention for enhancing the efficiency of electrocatalysts and photocatalysts. Despite substantial progress in these fields, there remains a notable absence of comprehensive and insightful articles providing a clear understanding of nanoconfined catalysts. This review addresses this gap by delving into nanoconfined catalysts for electrocatalytic and photocatalytic energy conversion.

Research on the spatiotemporal distribution and control degree of soil erosion in Dali River Basin.

The Dali River basin as the representative areas of the middle reaches of the Yellow River. Accurately evaluating the degree of soil erosion control is very important for soil erosion control. In response to the problems existing in the current research on soil erosion control degree (SECD) methods, the maximum possible soil erosion modulus is introduced into the evaluation model.

Pairing Oxygen Reduction and Water Oxidation for Dual-Pathway HO Production.

Hydrogen peroxide (HO) is a crucial chemical applied in various industry sectors. However, the current industrial anthraquinone process for HO synthesis is carbon-intensive. With sunlight and renewable electricity as energy inputs, photocatalysis and electrocatalysis have great potential for green HO production from oxygen (O) and water (HO).

Type II photoinitiators with collagen-based cyanine for cell encapsulation under green-red LED.

3D bioprinting with cell-laden materials is an emerging technique for fabricating functional tissue constructs. However, current cell-laden bioinks often lack sufficient cytocompatibility with commonly used UV-light sources. In this study, green to red photoinduced hydrogel crosslinking was obtained by introducing synthesized biosafety photoinitiators and used in light-based direct ink writing (DIW) 3D printing for enabling cell encapsulation successfully.

Functionalized 2D membranes for separations at the 1-nm scale.

The ongoing evolution of two-dimensional (2D) material-based membranes has prompted the realization of mass separations at the 1-nm scale due to their well-defined selective nano- and subnanochannels. Strategic membrane functionalization is further found to be key to augmenting channel accuracy and efficiency in distinguishing ions, gases and molecules within this range and is thus trending as a research focus in energy-, resource-, environment- and pharmaceutical-related applications. In this review, we present the fundamentals underpinning functionalized 2D membranes in various separations, elucidating the critical "method-interaction-property" relationship.

Accurate prediction of solvent flux in sub-1-nm slit-pore nanosheet membranes.

Nanosheet-based membranes have shown enormous potential for energy-efficient molecular transport and separation applications, but designing these membranes for specific separations remains a great challenge due to the lack of good understanding of fluid transport mechanisms in complex nanochannels. We synthesized reduced MXene/graphene hetero-channel membranes with sub-1-nm pores for experimental measurements and theoretical modeling of their structures and fluid transport rates. Our experiments showed that upon complete rejection of salt and organic dyes, these membranes with subnanometer channels exhibit remarkably high solvent fluxes, and their solvent transport behavior is very different from their homo-structured counterparts.

Novel D-π-A hemicyanine dye as photoinitiators for in situ hydrogel formation and DLP printing.

The field of biofabrication imposes stringent requirements on the polymerization activity and biosafety of photopolymeric hydrogel systems. In this investigation, we designed and synthesized four hemicyanine dyes with a D-π-A structure specifically tailored for biofabrication purposes. These novel dyes, incorporating carbazole (CZ), triphenylamine (TPA), anthracene (AN), and benzodithiophene (BDT) as electron donors, along with heterocyclic salt (IN) as electron acceptors, were prepared using a straightforward synthesis method.

Reversible pH-Gated MXene Membranes with Ultrahigh Mono-/Divalent-Ion Selectivity.

Artificial ion channel membranes hold high promise in water treatment, nanofluidics, and energy conversion, but it remains a great challenge to construct such smart membranes with both reversible ion-gating capability and desirable ion selectivity. Herein, we constructed a smart MXene-based membrane via -phenylenediamine functionalization (MLM-PPD) with highly stable and aligned two-dimensional subnanochannels, which exhibits reversible ion-gating capability and ultrahigh metal ion selectivity similar to biological ion channels. The pH-sensitive groups within the MLM-PPD channel confers excellent reversible Mg-gating capability with a pH-switching ratio of up to 100.

Electricity generation from carbon dioxide adsorption by spatially nanoconfined ion separation.

Selective ion transport underpins fundamental biological processes for efficient energy conversion and signal propagation. Mimicking these 'ionics' in synthetic nanofluidic channels has been increasingly promising for realizing self-sustained systems by harvesting clean energy from diverse environments, such as light, moisture, salinity gradient, etc. Here, we report a spatially nanoconfined ion separation strategy that enables harvesting electricity from CO adsorption.

Understanding the Electrochemical Extraction of Lithium from Ultradilute Solutions.

The electrochemical extraction of lithium (Li) from aqueous sources using electrochemical means is a promising direct Li extraction technology. However, to this date, most electrochemical Li extraction studies are confined to Li-rich brine, neglecting the practical and existing Li-lean resources, with their overall extraction behaviors currently not fully understood. More still, the effect of elevated sodium (Na) concentrations typically found in most Li-lean water sources on Li extraction is unclear.

Two-dimensional MXene membranes with biomimetic sub-nanochannels for enhanced cation sieving.

Membranes with high ion permeability and selectivity are of considerable interest for sustainable water treatment, resource extraction and energy storage. Herein, inspired by K channel of streptomyces A (KcsA K), we have constructed cation sieving membranes using MXene nanosheets and Ethylenediaminetetraacetic acid (EDTA) molecules as building blocks. Numerous negatively charged oxygen atoms of EDTA molecules and 6.

Nanoconfinement enabled non-covalently decorated MXene membranes for ion-sieving.

Covalent modification is commonly used to tune the channel size and functionality of 2D membranes. However, common synthesis strategies used to produce such modifications are known to disrupt the structure of the membranes. Herein, we report less intrusive yet equally effective non-covalent modifications on TiCT MXene membranes by a solvent treatment, where the channels are robustly decorated by protic solvents via hydrogen bond network.

Dehydration-enhanced ion-pore interactions dominate anion transport and selectivity in nanochannels.

State-of-the-art ion-selective membranes with ultrahigh precision are of significance for water desalination and energy conservation, but their development is limited by the lack of understanding of the mechanisms of ion transport at the subnanometer scale. Herein, we investigate transport of three typical anions (F, Cl, and Br) under confinement using in situ liquid time-of-flight secondary ion mass spectrometry in combination with transition-state theory. The operando analysis reveals that dehydration and related ion-pore interactions govern anion-selective transport.

Smart utilisation of reverse solute diffusion in forward osmosis for water treatment: A mini review.

Forward osmosis (FO) has been widely studied as a promising technology in wastewater treatment, but undesirable reverse solute diffusion (RSD) is inevitable in the FO process. The RSD is generally regarded as a negative factor for the FO process, resulting in the loss of draw solutes and reduced FO efficiency. Conventional strategies to address RSD focus on reducing the amount of reverse draw solutes by fabricating high selective FO membranes and/or selecting the draw solute with low diffusion.

Scalable high yield exfoliation for monolayer nanosheets.

Although two-dimensional (2D) materials have grown into an extended family that accommodates hundreds of members and have demonstrated promising advantages in many fields, their practical applications are still hindered by the lack of scalable high-yield production of monolayer products. Here, we show that scalable production of monolayer nanosheets can be achieved by a facile ball-milling exfoliation method with the assistance of viscous polyethyleneimine (PEI) liquid. As a demonstration, graphite is effectively exfoliated into graphene nanosheets, achieving a high monolayer percentage of 97.

Photo-electrochemical oxidation herbicides removal in stormwater: Degradation mechanism and pathway investigation.

Although advanced oxidation processes (AOPs) such as photoelectrochemical oxidation (PECO), electrochemical oxidation (ECO) and photocatalytic oxidation (PCO), have shown potential for wastewater treatment, their application in urban stormwater has rarely been studied. This paper explored their major degradation mechanisms and possible degradation pathways of herbicides for stormwater applications (with treatment difficulty compared with wastewater). PECO and ECO showed excellent removal performance for diuron (100 %) and moderate for atrazine (around 35 %) under a relatively low potential (2 V).

Novel Poly(ester amide) Membranes with Tunable Crosslinked Structures for Nanofiltration.

Tuning the crosslinking density of interfacial-polymerized nanofiltration (NF) membranes varying from loose to dense structures can make them meet the demand of various applications. The properties (e.g.

Monodispersed CuO nanoparticles supported on mineral substrates for groundwater remediation via a nonradical pathway.

Nonradical oxidation based on singlet oxygen (O) has attracted great interest in groundwater remediation due to the selective oxidation property and good resistance to background constituents. Herein, recoverable CuO nanoparticles (NPs) supported on mineral substrates (SiO) were prepared by calcination of surface-coated metal-plant phenolic networks and explored for peroxymonosulfate (PMS) activation to generate O for degrading organic pollutants in groundwater. CuO NPs with a close particle size (40 nm) were spatially monodispersed on SiO substrates, allowing highly exposure of active sites and consequently leading to outstanding catalytic performance.

Insight into the Reactivity of Carbon Structures for Nitrogen Reduction Reaction.

Graphene-based structures have been widely reported as promising metal-free catalysts for nitrogen reduction reaction. To explain the reactivity origin, various structures have been proposed and debated, including defects, functional groups, and doped heteroatoms. This computational work demonstrates that these structures may evolve from one to another under electrochemical conditions, generating weakly coordinated carbons, which have been identified as the active sites for N adsorption and activation.