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Natural polymers are attractive sustainable materials for production of fibers and composite materials. Cotton and flux are traditional plants used to produce textiles with comforting properties while technologies like Viscose, Lyocell and Ioncell-F allowed to extent fiber use into regenerated cellulose from wood. Neither natural nor man-made fibers completely satisfy the needs for cellulose based fabrics boosting development of new approaches to bring more sustainability into the fashion. Technologies like Spinnova are arising based on the spinning of mechanically pretreated cellulose materials with a lower environmental impact though challenged by the fiber quality and strength related to the inconsistency of the mechanical fibers. Nanoscaled cellulose is an excellent solution to improve the consistency of spin fibers, but charges introduced by traditional chemical treatments prevent rebuilding native hydrogen bonding and compromise the mechanical properties especially in wet conditions. We used nanocellulose with low surface charge isolated using reactive eutectic media to spin fibers able to restore the native hydrogen bonding and enable constitutional mechanical strength of cellulose. We performed un-optimized spinning to reveal the intrinsic properties of the fibers and confirmed the preserved strength of wet fibers compliant with the low surface charge enabling further engineering towards cotton-like fabric from wood. [ABSTRACT FROM AUTHOR]

Le Chatelier's principle is a basic rule in textbook defining the correlations of reaction activities and specific system parameters (like concentrations), serving as the guideline for regulating chemical/catalytic systems. Here we report a model system breaking this constraint in O2 electroreduction in mixed dioxygen. We unravel the central role of creating single-zinc vacancies in a crystal structure that leads to enzyme-like binding of the catalyst with enhanced selectivity to O2, shifting the reaction pathway from Langmuir-Hinshelwood to an upgraded triple-phase Eley-Rideal mechanism. The model system shows minute activity alteration of H2O2 yields (25.89~24.99 mol gcat−1 h−1) and Faradaic efficiencies (92.5%~89.3%) in the O2 levels of 100%~21% at the current density of 50~300 mA cm−2, which apparently violate macroscopic Le Chatelier's reaction kinetics. A standalone prototype device is built for high-rate H2O2 production from atmospheric air, achieving the highest Faradaic efficiencies of 87.8% at 320 mA cm−2, overtaking the state-of-the-art catalysts and approaching the theoretical limit for direct air electrolysis (~345.8 mA cm−2). Further techno-economics analyses display the use of atmospheric air feedstock affording 21.7% better economics as comparison to high-purity O2, achieving the lowest H2O2 capital cost of 0.3 $ Kg−1. Given the recent surge of demonstrations on tailoring chemical/catalytic systems based on the Le Chatelier's principle, the present finding would have general implications, allowing for leveraging systems "beyond" this classical rule. The principle of Le Chatelier is a fundamental concept in textbooks, serving as a guiding principle for controlling chemical and catalytic systems. In this study, the authors present an oxygen electroreduction system based on a single zinc vacancy catalyst, which operates in a manner that extends "beyond" Le Chatelier's principle. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) converts wet biomass into hydrochar and a process liquid, but aromatic compounds in the products have been reported as a roadblock for soil applications as they can inhibit germination, plant growth, and soil microbial activity. Here, we compared HTC and hydrothermal humification (HTH) of cow manure digestate while varying the initial alkaline content by adding KOH. HTH converted 37.5 wt% of the feedstock to artificial humic acids (A-HAs) found in both solid and liquid, twice that of HTC. HTH reduced phenolic and furanic aromatic compounds by over 70% in solids and 90% in liquids. The A-HAs in HTH resemble natural humic acids (N-HA), based on FTIR, UV–vis spectra, and CHN and XRD analysis. The HTH liquid possesses 60% higher total organic carbon (TOC) than HTC. Although one-third of TOC can be precipitated as A-HA, a high TOC concentration remains in the liquid, which is shown to be mainly organic acids. Therefore, we also evaluated the HTC and HTH liquids for anaerobic biomethane production, and found that compared to the original cow manure digestate, the HTH liquids increased methane yield by 110.3 to 158.6%, a significant enhancement relative to the 17.2% increase seen with HTC liquid. The strong reduction in organic acids during biogas production from HTH liquid indicates the potential for converting soluble byproducts into methane, while maintaining high A-HAs levels in the solid product. Highlights: Hydrothermal humification of the digestate feedstock created about 37.5 wt% artificial humic acids in both solid and liquid phases. Increasing the alkaline content of the reaction media significantly decreased the aromatic content in the process liquid while increasing the concentration of organic acids and sugars. There was little to no gas production observed in the HTH process at higher alkaline contents, indicating carbon preservation in the liquid and solid phases. Anaerobic processing of the hydrothermal humification (HTH) process liquid resulted in a 158.6% increase in methane production compared to the primary biomass. The organic acid concentrations decreased after the anaerobic fermentation, while the main HTH product, artificial humic acids, remained nearly unchanged. [ABSTRACT FROM AUTHOR]

Herein, the feasibility of artificial black soil (ABS) derived from hydrothermal humification-hydrothermal carbonization (HTH-HTC) for restructuration of weak soil was verified. This study breaks through the long history of soil formation and evolution, and obtains reconstructed anthropogenic soil (AS) system which only takes one month, for the further application of rice seedlings. HTH-HTC derived by-products are slightly acidic, which facilitates the effective nutrient uptake and prevention of wilt diseases for acid-loving rice seedlings. AS mainly consists of the inherent components retained from weak soil such as SiO2 and minerals, and exogenous components such as artificial humic substances and hydrochar, as introduced by hydrothermal humification processes. Results exhibit that AS has high contents of ammonium nitrogen, organic matter, organic carbon, and abundant porous structure for nutrient transport and water holding, especially, the community diversity and richness of microbial system gets the expected recovery and new beneficial bacteria (such as Caballeronia calidae) or fungi (such as Humicola) appear. Positive effects of AS on agronomic traits in rice seedlings are quantified. As a general result, this study supports the application of AS in sustainable agriculture, and provides a novel strategy to tackle the already-omnipresent land degradation by anthropogenic misuse and larger scale accidents. Highlights: • Anthropogenic soil system was rapidly reconstructed through hydrothermal humification-hydrothermal carbonation technology. • Anthropogenic soil possesses multiple components-structure properties for nutrient transport and water retention. • Anthropogenic soil microbial systems recover and spread in 4 weeks. • Anthropogenic soil provides acidic environment to biochemically promote rice seedling growth. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride is widely studied in organic photoredox catalysis. Reductive quenching of carbon nitride excited state is postulated in many photocatalytic transformations. However, the reactivity of this species in the turn over step is less explored. In this work, we investigate electron and proton transfer from carbon nitride that is photocharged to a various extent, while the negative charge is compensated either by protons or ammonium cations. Strong stabilization of electrons by ammonium cations makes proton-coupled electron transfer uphill, and affords air-stable persistent carbon nitride radicals. In carbon nitrides, which are photocharged to a smaller extent, protons do not stabilize electrons, which results in spontaneous charge transfer to oxidants. Facile proton-coupled electron transfer is a key step in the photocatalytic oxidative-reductive cascade – tetramerization of benzylic amines. The feasibility of proton-coupled electron transfer is modulated by adjusting the extent of carbon nitride photocharging, type of counterion and temperature.Savateev et al. investigate proton-coupled electron transfer from persistent graphitic carbon nitride radical to oxygen and imines. The results of their study find application in cascade photocatalysis – selective tetramerization of benzylic amines. [ABSTRACT FROM AUTHOR]

For decarbonization of ammonia production in industry, alternative methods by exploiting renewable energy sources have recently been explored. Nonetheless, they still lack yield and efficiency to be industrially relevant. Here, we demonstrate an advanced approach of nitrogen fixation to synthesize ammonia at ambient conditions via laser–induced multiphoton dissociation of lithium oxide. Lithium oxide is dissociated under non–equilibrium multiphoton absorption and high temperatures under focused infrared light, and the generated zero–valent metal spontaneously fixes nitrogen and forms a lithium nitride, which upon subsequent hydrolysis generates ammonia. The highest ammonia yield rate of 30.9 micromoles per second per square centimeter is achieved at 25 °C and 1.0 bar nitrogen. This is two orders of magnitude higher than state–of–the–art ammonia synthesis at ambient conditions. The focused infrared light here is produced by a commercial simple CO2 laser, serving as a demonstration of potentially solar pumped lasers for nitrogen fixation and other high excitation chemistry. We anticipate such laser-involved technology will bring unprecedented opportunities to realize not only local ammonia production but also other new chemistries. Emerged sustainable techniques for nitrogen fixation still lack ammonia yield rate to be practically relevant. Here, the authors demonstrate a laser–induced method to deliver a yield rate of 30.9 µmol s-1 cm−2 at ambient conditions, which is two orders of magnitude higher than other methods. [ABSTRACT FROM AUTHOR]

Dopamine is not only a widely used commodity pharmaceutical for treating neurological diseases but also a highly attractive base for advanced carbon materials. Lignin, the waste from the lignocellulosic biomass industry, is the richest source of renewable aromatics on earth. Efficient production of dopamine direct from lignin is a highly desirable target but extremely challenging. Here, we report an innovative strategy for the sustainable production of dopamine hydrochloride from softwood lignin with a mass yield of 6.4 wt.%. Significantly, the solid dopamine hydrochloride is obtained by a simple filtration process in purity of 98.0%, which avoids the tedious separation and purification steps. The approach begins with the acid-catalyzed depolymerization, followed by deprotection, hydrogen-borrowing amination, and hydrolysis of methoxy group, transforming lignin into dopamine hydrochloride. The technical economic analysis predicts that this process is an economically competitive production process. This study fulfills the unexplored potential of dopamine hydrochloride synthesis from lignin. Efficient production of dopamine direct from lignin is a highly desirable target but extremely challenging. Here, we report an innovative strategy for the sustainable production of dopamine hydrochloride from softwood lignin with a mass yield of 6.4 wt.%. [ABSTRACT FROM AUTHOR]

Membrane-based water treatment processes offer possibility to alleviate the water scarcity dilemma in energy-efficient and sustainable ways, this has been exemplified in filtration membranes assembled from two-dimensional (2D) materials for water desalination purposes. Most representatives however tend to swell or disintegrate in a hydrated state, making precise ionic or molecular sieving a tough challenge. Here we report that the chemically robust 2D carbon nitride can be activated using aluminum polycations as pillars to modulate the interlayer spacing of the conjugated framework, the noncovalent interaction concomitantly affords a well-interlinked lamellar structure, to be carefully distinguished from random stacking patterns in conventional carbon nitride membranes. The conformally packed membrane is characterized by adaptive subnanochannel and structure integrity to allow excellent swelling resistance, and breaks permeability-selectivity trade-off limit in forward osmosis due to progressively regulated transport passage, achieving high salt rejection (>99.5%) and water flux (6 L m−2 h−1), along with tunable permeation behavior that enables water gating in acidic and alkaline environments. These findings position carbon nitride a rising building block to functionally expand the 2D membrane library for applications in water desalination and purification scenarios. Traditional carbon nitride membranes are generally presented with random stacking behavior leading to undesired separation performance. Here, authors create lamellar membranes via polycation pillaring to afford adaptive subnanochannels, overcoming the selectivity-permeability trade-off in forward osmosis. [ABSTRACT FROM AUTHOR]

Switchable gas separation membranes are intriguing systems for regulating the transport properties of gases. However, existing stimuli-responsive gas separation membranes suffer from either very slow response times or require high energy input for switching to occur. Accordingly, herein, we introduced light-switchable polymeric carbon nitride (pCN) gas separation membranes with fast response times prepared from melamine precursor through in-situ formation and deposition of pCN onto a porous support using chemical vapor deposition. Our systematic analysis revealed that the gas transport behavior upon light irradiation is fully governed by the polarizability of the permeating gas and its interaction with the charged pCN surface, and can be easily tuned either by controlling the power of the light and/or the duration of irradiation. We also demonstrated that gases with higher polarizabilities such as CO2 can be separated from gases with lower polarizability like H2 and He effectively with more than 22% increase in the gas/CO2 selectivity upon light irradiation. The membranes also exhibited fast response times (<1 s) and can be turned "on" and "off" using a single light source at 550 nm. Simuli-responsive separation membranes often suffer from slow response times or require high energy input for switching to occur. Here authors demonstrate light-switchable gas separation membranes based on polymeric carbon nitride with fast switching times for the efficient separation of gases with higher polarizabilities. [ABSTRACT FROM AUTHOR]

Aqueous zinc (Zn) chemistry features intrinsic safety, but suffers from severe irreversibility, as exemplified by low Coulombic efficiency, sustained water consumption and dendrite growth, which hampers practical applications of rechargeable Zn batteries. Herein, we report a highly reversible aqueous Zn battery in which the graphitic carbon nitride quantum dots additive serves as fast colloid ion carriers and assists the construction of a dynamic & self-repairing protective interphase. This real-time assembled interphase enables an ion-sieving effect and is found actively regenerate in each battery cycle, in effect endowing the system with single Zn2+ conduction and constant conformal integrality, executing timely adaption of Zn deposition, thus retaining sustainable long-term protective effect. In consequence, dendrite-free Zn plating/stripping at ~99.6% Coulombic efficiency for 200 cycles, steady charge-discharge for 1200 h, and impressive cyclability (61.2% retention for 500 cycles in a Zn | |MnO2 full battery, 73.2% retention for 500 cycles in a Zn | |V2O5 full battery and 93.5% retention for 3000 cycles in a Zn | |VOPO4 full battery) are achieved, which defines a general pathway to challenge Lithium in all low-cost, large-scale applications. Metallic zinc is an ideal anode material for aqueous rechargeable batteries but reversibility is a challenge. Here, the authors realise a dynamic real-time reconstructed interphase on zinc anode formed by graphitic carbon nitride quantum dot as an electrolyte additive to improve the performance of Zn metal anodes. [ABSTRACT FROM AUTHOR]

Chromoselective photocatalysis offers an intriguing opportunity to enable a specific reaction pathway out of a potentially possible multiplicity for a given substrate by using a sensitizer that converts the energy of incident photon into the redox potential of the corresponding magnitude. Several sensitizers possessing different discrete redox potentials (high/low) upon excitation with photons of specific wavelength (short/long) have been reported. Herein, we report design of molecular structures of two-dimensional amorphous covalent triazine-based frameworks (CTFs) possessing intraband states close to the valence band with strong red edge effect (REE). REE enables generation of a continuum of excited sites characterized by their own redox potentials, with the magnitude proportional to the wavelength of incident photons. Separation of charge carriers in such materials depends strongly on the wavelength of incident light and is the primary parameter that defines efficacy of the materials in photocatalytic bromination of electron rich aromatic compounds. In dual Ni-photocatalysis, excitation of electrons from the intraband states to the conduction band of the CTF with 625 nm photons enables selective formation of C‒N cross-coupling products from arylhalides and pyrrolidine, while an undesirable dehalogenation process is completely suppressed. Chromoselective catalysis offers an intriguing opportunity to enable a specific reaction pathway in photocatalysis. Here, the authors look into the ability of covalent triazine frameworks to enable the synthesis of different organic compounds by using safer red light instead of harsh UV light. [ABSTRACT FROM AUTHOR]

The transport of fluids in channels with diameter of 1-2 nm exhibits many anomalous features due to the interplay of several genuinely interfacial effects. Quasi-unidirectional ion transport, reminiscent of the behavior of membrane pores in biological cells, is one phenomenon that has attracted a lot of attention in recent years, e.g., for realizing diodes for ion-conduction based electronics. Although ion rectification has been demonstrated in many asymmetric artificial nanopores, it always fails in the high-concentration range, and operates in either acidic or alkaline electrolytes but never over the whole pH range. Here we report a hierarchical pore architecture carbon membrane with a pore size gradient from 60 nm to 1.4 nm, which enables high ionic rectification ratios up to 104 in different environments including high concentration neutral (3 M KCl), acidic (1 M HCl), and alkaline (1 M NaOH) electrolytes, resulting from the asymmetric energy barriers for ions transport in two directions. Additionally, light irradiation as an external energy source can reduce the energy barriers to promote ions transport bidirectionally. The anomalous ion transport together with the robust nanoporous carbon structure may find applications in membrane filtration, water desalination, and fuel cell membranes. Ion transport through nano channels can exhibit intriguing non-linear behaviour. Here, Chen et al. fabricate a hierarchical system of sandwiched carbon membranes of wide and narrow pores with substantial enhancement in rectification ratio of the ionic current, adjustable by optical triggers. [ABSTRACT FROM AUTHOR]

The activation of C–H bonds is a central challenge in organic chemistry and usually a key step for the retro-synthesis of functional natural products due to the high chemical stability of C–H bonds. Electrochemical methods are a powerful alternative for C–H activation, but this approach usually requires high overpotential and homogeneous mediators. Here, we design electron-deficient W2C nanocrystal-based electrodes to boost the heterogeneous activation of C–H bonds under mild conditions via an additive-free, purely heterogeneous electrocatalytic strategy. The electron density of W2C nanocrystals is tuned by constructing Schottky heterojunctions with nitrogen-doped carbon support to facilitate the preadsorption and activation of benzylic C–H bonds of ethylbenzene on the W2C surface, enabling a high turnover frequency (18.8 h−1) at a comparably low work potential (2 V versus SCE). The pronounced electron deficiency of the W2C nanocatalysts substantially facilitates the direct deprotonation process to ensure electrode durability without self-oxidation. The efficient oxidation process also boosts the balancing hydrogen production from as-formed protons on the cathode by a factor of 10 compared to an inert reference electrode. The whole process meets the requirements of atomic economy and electric energy utilization in terms of sustainable chemical synthesis. Designing electrode materials for mild and additive-free activation of C–H bonds is of great challenge. The authors report the application of electron-deficient W2C nanocrystal electrodes to boost the dissociation of C-H bonds toward the efficient alkoxylation and hydrogen evolution reactions. [ABSTRACT FROM AUTHOR]

How a catalyst behaves microscopically under reaction conditions, and what kinds of active sites transiently exist on its surface, is still very much a mystery to the scientific community. Here we present an in situ study on the red-ox behaviour of copper in the model reaction of hydrogen oxidation. Direct imaging combined with on-line mass spectroscopy shows that activity emerges near a phase boundary, where complex spatio-temporal dynamics are induced by the competing action of simultaneously present oxidizing and reducing agents. Using a combination of in situ imaging with in situ X-ray absorption spectroscopy and scanning photoemission microscopy, we reveal the relation between chemical and morphological dynamics and demonstrate that a static picture of active sites is insufficient to describe catalytic function of redox-active metal catalysts. The observed oscillatory redox dynamics provide a unique insight on phase-cooperation and a convenient and general mechanism for constant re-generation of transient active sites. How a catalyst behaves microscopically under reaction conditions, and what kinds of active sites transiently exist on its surface, is still very much a mystery to the scientific community. Here the authors report on in situ observation of a redox active copper catalyst by a combination of in situ imaging and spectroscopy tools. [ABSTRACT FROM AUTHOR]

The potassium salt of polyheptazine imide (K–PHI) is a promising photocatalyst for various chemical reactions. From powder X–ray diffraction data an idealized structural model of K–PHI has been derived. Using atomic coordinates of this model we defined an energetically optimized K–PHI structure, in which the K ions are present in the pore and between the PHI–planes. The distance between the anion framework and K+ resembles a frustrated Lewis pair-like structure, which we denote as frustrated Coulomb pair that results in an interesting adsorption environment for otherwise non-adsorbing, non-polar gas molecules. We demonstrate that even helium (He) gas molecules, which are known to have the lowest boiling point and the lowest intermolecular interactions, can be adsorbed in this polarized environment with an adsorption energy of − 4.6 kJ mol−1 per He atom. The interaction between He atoms and K–PHI is partially originating from charge transfer, as disclosed by our energy decomposition analysis based on absolutely localized molecular orbitals. Due to very small charge transfer interactions, He gas adsorption saturates at 8 at%, which however can be subject to further improvement by cation variation. [ABSTRACT FROM AUTHOR]

Small organic radicals are ubiquitous intermediates in photocatalysis and are used in organic synthesis to install functional groups and to tune electronic properties and pharmacokinetic parameters of the final molecule. Development of new methods to generate small organic radicals with added functionality can further extend the utility of photocatalysis for synthetic needs. Herein, we present a method to generate dichloromethyl radicals from chloroform using a heterogeneous potassium poly(heptazine imide) (K-PHI) photocatalyst under visible light irradiation for C1-extension of the enone backbone. The method is applied on 15 enones, with γ,γ-dichloroketones yields of 18–89%. Due to negative zeta-potential (−40 mV) and small particle size (100 nm) K-PHI suspension is used in quasi-homogeneous flow-photoreactor increasing the productivity by 19 times compared to the batch approach. The resulting γ,γ-dichloroketones, are used as bifunctional building blocks to access value-added organic compounds such as substituted furans and pyrroles. Long-lived carbon nitride radicals have been used in several photocatalytic reactions. Herein, long-lived potassium poly(heptazine imide) radicals enable synthesis of γ,γ-dichloroketones from enones by addition of CHCl2 moiety, generated from chloroform, to the C=C bond. [ABSTRACT FROM AUTHOR]

High-performance thermally insulating materials from renewable resources are needed to improve the energy efficiency of buildings. Traditional fossil-fuel-derived insulation materials such as expanded polystyrene and polyurethane have thermal conductivities that are too high for retrofitting or for building new, surface-efficient passive houses. Tailored materials such as aerogels and vacuum insulating panels are fragile and susceptible to perforation. Here, we show that freeze-casting suspensions of cellulose nanofibres, graphene oxide and sepiolite nanorods produces super-insulating, fire-retardant and strong anisotropic foams that perform better than traditional polymer-based insulating materials. The foams are ultralight, show excellent combustion resistance and exhibit a thermal conductivity of 15 mW m−1 K−1, which is about half that of expanded polystyrene. At 30 °C and 85% relative humidity, the foams retained more than half of their initial strength. Our results show that nanoscale engineering is a promising strategy for producing foams with excellent properties using cellulose and other renewable nanosized fibrous materials. [ABSTRACT FROM AUTHOR]

Soil amendment with hydrochar produced by hydrothermal carbonization of biomass is suggested as a simple, cheap, and effective method for increasing soil C. We traced C derived from corn silage hydrochar (δC of −13 ‰) added to 'coarse' and 'fine' textured soils (δC of −27 ‰ for native soil C (SOC)) over two cropping seasons. Respiration rates increased in both soils ( p < 0.001) following hydrochar addition, and most of this extra respiration was derived from hydrochar C. Dissolved losses accounted for ~5 % of added hydrochar C ( p < 0.001). After 1 year, 33 ± 8 % of the added hydrochar C was lost from both soils. Decomposition rates for the roughly two thirds of hydrochar that remained were very low, with half-life for less estimated at 19 years. In addition, hydrochar-amended soils preserved 15 ± 4 % more native SOC compared to controls (negative priming). Hydrochar negatively affected plant height ( p < 0.01) and biomass ( p < 0.05) in the first but not the second crop grown on both soils. Our results confirm previous laboratory studies showing that initially, hydrochar decomposes rapidly and limits plant growth. However, the negative priming effect and persistence of added hydrochar C after 1 year highlight its soil C sequestration potential, at least on decadal timescales. [ABSTRACT FROM AUTHOR]

The production of hydrogen from water using a catalyst and solar energy is an ideal future energy source, independent of fossil reserves. For an economical use of water and solar energy, catalysts that are sufficiently efficient, stable, inexpensive and capable of harvesting light are required. Here, we show that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor. Contrary to other conducting polymer semiconductors, carbon nitride is chemically and thermally stable and does not rely on complicated device manufacturing. The results represent an important first step towards photosynthesis in general where artificial conjugated polymer semiconductors can be used as energy transducers. [ABSTRACT FROM AUTHOR]

Morphosynthesis strategies inspired by biomineralization processes gives access to a wide range of fascinating and useful crystalline mesostructures. Biomimetic synthesis of inorganic materials with complex shapes can now be used to control the nucleation, tensorial growth, and alignment of inorganic crystals in a way previously not practicable. Double hydrophilic block copolymers (DHBCs) consisting of a hydrophilic block strongly interacting with inorganic minerals, and a non-interacting hydrophilic block, were recently introduced for the control of mineralization reactions. DHBCs are 'improved versions' of the previously used polyelectrolytes or amphiphiles and are extraordinarily effective in crystallization control. Here, we report on the formation of helices of achiral BaCO3 nanocrystals in the presence of a racemic DHBC suggesting that a helical alignment can be induced by racemic polymers through selective adsorption on the (110) face of nanocrystals. This mechanism is the key for a better understanding of the self-assembly of chiral organic–inorganic superstructures that don't follow a direct template route. [ABSTRACT FROM AUTHOR]

Innovative strategies to produce well-defined nanoparticles and other nanostructures such as nanofibres, quantum wells and mesoporous materials have revitalized materials science for the potential benefit to society. Here, we report a controlled process, involving soft-chemistry-based deposition, template-assisted mesostructured growth, and tuned annealing conditions that allows the preparation of ordered mesoporous crystalline networks and mesostructured nano-island single layers, composed of multicationic metal oxides having perovskite, tetragonal or ilmenite structures. This strategy to obtain meso-organized multi-metal-oxide nanocrystalline films (M3NF) bridges the gap between conventional mesoporous materials and the remarkable properties of crystalline ternary or quaternary metallic oxides. Nanocrystalline mesoporous films with controlled wall thickness (10–20 nm) of dielectric SrTiO3, photoactive MgTa2O6 or ferromagnetic semi-conducting CoxTi1−xO2−x were prepared by evaporation-induced self-assembly (EISA) using a specially designed non-ionic block-copolymer template. A tuned thermal treatment of the mesoporous films permits the transfer of the wall structure into nanocrystallites, with all tectonic units being tightly incorporated into mechanically stable ordered tri- or bidimensional nanocrystalline networks. This methodology should allow multifunctionalization, miniaturization and integration during development of devices such as smart sensors and actuators, better-performing photocatalysts, and fast electrochromic devices. On the other hand, organized arrays of dispersed ferromagnetic or ferroelectric nanoparticles are promising materials for spintronics and for cheap, non-volatile 'flash' memories. [ABSTRACT FROM AUTHOR]

Precipitation of calcium phosphate in a double-jet experiment in the presence of sodium polyaspartic acid results in a structural evolution of stable colloidal objects with a variety of unconventional morphologies. This structural evolution is characterized by a combination of techniques, namely static and dynamic light scattering, small-angle and wide-angle X-ray scattering, and transmission electron microscopy. It is shown that after immediate formation of amorphous precursor nanoparticles with a “parachute architecture”, the system transfers into a hollow sphere morphology in the 500-nm region and is composed of plateletlike nanocrystals, and again is transferred into a final, “snowball-like” morphology of high structural definition and monodispersity. The kinetics depends on the amount and the molecular weight of the polymer, but similar structural elements are found in all the cases examined. When repeated in a triple-jet experiment, which also ensures a constant polymer concentration, it was possible to intercept a postulated intermediate structure in practically complete yield, namely crystalline hydroxyapatite nanofibres with extremely high axial ratios which form an interwoven gel. [ABSTRACT FROM AUTHOR]

Production of ammonia is currently realized by the Haber–Bosch process, while electrochemical N2 fixation under ambient conditions is recognized as a promising green substitution in the near future. A lack of efficient electrocatalysts remains the primary hurdle for the initiation of potential electrocatalytic synthesis of ammonia. For cheaper metals, such as copper, limited progress has been made to date. In this work, we boost the N2 reduction reaction catalytic activity of Cu nanoparticles, which originally exhibited negligible N2 reduction reaction activity, via a local electron depletion effect. The electron-deficient Cu nanoparticles are brought in a Schottky rectifying contact with a polyimide support which retards the hydrogen evolution reaction process in basic electrolytes and facilitates the electrochemical N2 reduction reaction process under ambient aqueous conditions. This strategy of inducing electron deficiency provides new insight into the rational design of inexpensive N2 reduction reaction catalysts with high selectivity and activity. Electrocatalytic nitrogen reduction is promising for ammonia production, but electrocatalysts are limited by low efficiency and high cost. Here, the authors report electron-deficient copper nanoparticles, induced by rectifying contact with polyimide, for selective reduction of nitrogen to ammonia. [ABSTRACT FROM AUTHOR]

Addition of N-centered radicals to C=C bonds or insertion into C-H bonds is well represented in the literature. These reactions have a tremendous significance, because they afford polyfunctionalized organic molecules. Despite the tetrahydroisoquinoline (THIQ) moiety widely occurring in natural biologically active compounds, N-unsubstituted THIQs as a source of N-centered radicals are not studied. Herein, we report a photocatalytic reaction between tetrahydroisoquinoline and chalcones that gives N-fused pyrroles—1,3-disubstituted-5,6-dihydropyrrolo[2,1-a]isoquinolines (DHPIQ). The mechanism includes at least two photocatalytic events in one pot: (1) C-N bond formation; (2) C-C bond formation. In this process potassium poly(heptazine imide) is used as a visible light active heterogeneous and recyclable photocatalyst. Fifteen N-fused pyrroles are reported with 65-90% isolated yield. DHPIQs are characterized by UV-vis and fluorescence spectroscopy, while the fluorescence quantum efficiency of fluorinated DHPIQs reaches 24%. Photochemistry offers new means to perform organic chemistry, although these transformations typically require additives. Here, the authors study reactions between tetrahydroisoquinolines and chalcones under visible light using carbon nitrides for construction of novel fluorescent heterocycles. [ABSTRACT FROM AUTHOR]

The original version of this Article contained errors in Figure 3. In Fig. 3d, the label 'With light irradiation' was originally incorrectly given as 'Without light irradiation'. In Fig. 3f, the label 'Without light irradiation' was originally incorrectly given as 'With light irradiation'. This has been corrected in both the PDF and HTML versions of the Article. [ABSTRACT FROM AUTHOR]

Biological light-driven ion pumps move ions against a concentration gradient to create a membrane potential, thus converting sunlight energy directly into an osmotic potential. Here, we describe an artificial light-driven ion pump system in which a carbon nitride nanotube membrane can drive ions thermodynamically uphill against an up to 5000-fold concentration gradient by illumination. The separation of electrons and holes in the membrane under illumination results in a transmembrane potential which is thought to be the foundation for the pumping phenomenon. When used for harvesting solar energy, a sustained open circuit voltage of 550 mV and a current density of 2.4 μA/cm2 can reliably be generated, which can be further scaled up through series and parallel circuits of multiple membranes. The ion transport based photovoltaic system proposed here offers a roadmap for the development of devices by using simple, cheap, and stable polymeric carbon nitride. Biological light-driven ion pumps move ions against a concentration gradient to create a membrane potential, converting sunlight into an osmotic potential. Here, the authors make an artificial ion pump which drives ions thermodynamically uphill against a large concentration gradient upon illumination, which can be used for harvesting solar energy. [ABSTRACT FROM AUTHOR]