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The effect of operating conditions on the surface composition and evolution of (La0.8Sr0.2)0.95Cr0.5Fe0.5O3−δ (LSCrF8255) as a model perovskite oxide was investigated. LSCrF8255 pellets were annealed under dry oxygen (pO2 = 200 mbar), wet oxygen (pO2 = 200 mbar, pH2O = 30 mbar), and water vapour (pO2 < 1 mbar, pH2O = 30 mbar) environments to reflect the applications of perovskite materials as electrodes for oxygen reduction/evolution and H2O electrolysis in electrochemical energy conversion devices such as solid oxide fuel/electrolysis cells (SOFCs/SOECs) and oxygen transport membranes (OTMs). A series of comprehensive surface characterization techniques were applied, including low energy ion scattering spectroscopy (LEIS), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and energy-dispersive X-ray spectroscopy (EDX). Our comprehensive study showed that after annealing at 900 °C for 27 hours, a severe level of Sr surface segregation occurred on the sample annealed in both dry oxygen and water vapour but in different manners, whereas on the sample annealed in wet oxygen, Sr segregation was likely suppressed. In addition, the Sr segregation behaviour can be correlated to other mass transport phenomena, such as Cr evaporation and redeposition and Si deposition, as well as to crystal orientation and defects such as grain boundaries and dislocations. Apart from the Sr-enriched surface precipitates, phase separation was consistently observed on the samples annealed in all three conditions. The secondary phase was found to be B-site cation enriched (significantly Fe enriched, relatively Cr enriched) and A-site cation (La and Sr) deficient. Moreover, in contrast to the Sr enriched surface, a La enriched surface was observed on samples annealed in dry oxygen at 600 and 700 °C, which was found to be potentially caused by the Sr and Cr surface evaporation processes.

As complex materials are widely used in emerging technologies for environmental and energy applications, it is important to be able to quantify their stimuli-response behaviors. Light is a useful stimulus to modulate multifunctional electrochemical, magnetic, optical, and structural properties in metal–organic frameworks (MOFs); however, the underlying mechanisms and kinetics of light-induced structural changes are not well understood. Herein, a double [2 + 2] photocyclization in photoactive [Cd2(stil)2(Py2TTF)2] (stil2– = 4,4′-stilbenedicarboxylic acid, Py2TTF = 2,6-bis(4′-pyridyl)-tetrathiafulvalene) offers a powerful platform to quantitatively probe solid-state photocyclization kinetics. Variable-temperature Raman spectroscopy revealed a nonlinear temperature dependence of these parameters, which could be analyzed using the Johnson–Mehl–Avrami–Kolmogorov (JMAK) kinetic model to yield a maximum rate observed between 0 °C and 20 °C of approximately 0.172 s–1. These results offer the first example of the quantification of the photocyclization kinetics in a MOF. Density functional theory (DFT) calculations support a singlet reaction mechanism for the double [2 + 2] photocyclization, which is facilitated by the cofacial alignment of Py2TTF ligands. Establishing mechanistic and kinetic models that can be applied to multistimuli-responsive materials provides a powerful platform for their future design for applications in sensing, switching, and molecular separations.

Hybrid inorganic-organic perovskites have attracted considerable attention over recent years as promising processable electronic materials. In particular, the rich structural dynamics of these ‘soft’ materials has become a subject of investigation and debate due to their direct influence on the perovskites' optoelectronic properties. Significant effort has focused on understanding the role and behaviour of the organic cations within the perovskite, as their rotational dynamics may be linked to material stability, heterogeneity and performance in (opto)electronic devices. To this end, we use two-dimensional IR spectroscopy (2DIR) to understand the effect of partial caesium alloying on the rotational dynamics of the methylammonium cation in the archetypal hybrid perovskite CH3NH3PbI3. We find that caesium incorporation primarily inhibits the slower ‘reorientational jump’ modes of the organic cation, whilst a smaller effect on the fast ‘wobbling time’ may be due to distortions and rigidisation of the inorganic cuboctahedral cage. 2DIR centre-line-slope analysis further reveals that while static disorder increases with caesium substitution, the dynamic disorder (reflected in the phase memory of the N-H stretching mode of methylammonium) is largely independent of caesium addition. Our results contribute to the development of a unified model of cation dynamics within organohalide perovskites.

Histidine, a widely used buffer in monoclonal antibody (mAb) formulations, is known to reduce antibody aggregation. While experimental studies suggest a nonelectrostatic, nonstructural (relating to secondary structure preservation) origin of the phenomenon, the underlying microscopic mechanism behind the histidine action is still unknown. Understanding this mechanism will help evaluate and predict the stabilizing effect of this buffer under different experimental conditions and for different mAbs. We have used all-atom molecular dynamics simulations and contact-based free energy calculations to investigate molecular-level interactions between the histidine buffer and mAbs, which lead to the observed stability of therapeutic formulations in the presence of histidine. We reformulate the Spatial Aggregation Propensity index by including the buffer-protein interactions. The buffer adsorption on the protein surface leads to lower exposure of the hydrophobic regions to water. Our analysis indicates that the mechanism behind the stabilizing action of histidine is connected to the shielding of the solvent-exposed hydrophobic regions on the protein surface by the buffer molecules.

This article discusses challenges faced in the development of new Ni-based superalloys for applications in the hottest sections of turbine engines and the use of atom probe tomography and correlative microscopy for characterization of these complex alloys with regards to microstructural and compositional design. The two strengthening phases γ and γ′ are introduced and the precipitation of topologically close-packed phases and their potential detrimental effects on superalloy properties are reviewed. Mechanisms of environmental degradation, namely oxidation and hot corrosion, are elucidated and recent research studies on a new phenomenon of hot corrosion at relatively low temperatures below 600°C are discussed. The effect of individual alloying elements on superalloy properties is reviewed, with a focus on Mo and W. The use of atom probe in correlation with state-of-the-art microscopy, spectroscopy and diffraction techniques to study and understand oxidation and corrosion of Ni-based superalloys, including crack tip investigations, is presented.Graphical abstract

Crystal regeneration has been observed in macroscopic paracetamol crystals post breakage along their cleavage plane. High resolution imaging confirmed regeneration rates to be 3-fold faster than growth prior to breakage. Further analysis of the solute-solvent interactions is required to elucidate the process which currently lacks linearity with traditional growth theories.

Post-polymerisation functionalisation provides a facile and efficient way for the introduction of functional groups on the backbone of conjugated polymers. Using post-polymerisation functionalisation approaches, the polymer chain length is usually not affected, meaning that the resulting polymers only differ in their attached functional groups or side chains, which makes them particularly interesting for investigating the influence of the different groups on the polymer properties. For such functionalisations, highly efficient and selective reactions are needed to avoid the formation of complex mixtures or permanent defects in the polymer backbone. A variety of suitable synthetic approaches and reactions that fulfil these criteria have been identified and reported. In this review, a thorough overview is given of the post-polymerisation functionalisations reported to date, with the methods grouped based on the type of reaction used: cycloaddition, oxidation/reduction, nucleophilic aromatic substitution, or halogenation and subsequent cross-coupling reaction. Instead of modifications on the aliphatic side chains of the conjugated polymers, we focus on modifications directly on the conjugated backbones, as these have the most pronounced effect on the optical and electronic properties. Some of the discussed materials have been used in applications, ranging from solar cells to bioelectronics. By providing an overview of this versatile and expanding field for the first time, we showcase post-polymerisation functionalisation as an exciting pathway for the creation of new conjugated materials for a range of applications.

Understanding of the protonic defect transport mechanism in Ba(Ce,Zr)O3 perovskite oxides and defining the appropriate temperature range for ionic conductivity are fundamental to material design and application as electrolytes for solid oxide fuels and electrolyzer cells, isotopic separation membranes, and hydrogen sensors. Structural features of the material, and lattice distortions and proton diffusion are key factors that define the protonic conduction. The crystal structure of protonated and deuterated BaCe0.4Zr0.4Y0.2O3-? (BCZY) perovskite and its correlation with protonic transport was studied by in situ neutron powder diffraction (NPD) and complementary thermogravimetry (TG), quasi-elastic neutron scattering (QENS) and isotope exchange depth profiling (IEDP) techniques. A second order phase transition from rhombohedral to cubic symmetry takes place at intermediate temperatures (400-600 °C). Dynamic measurements of NPD allowed the detection of the temperature of the phase transition for BCZY at around 520 °C. Crystallographic and microstructural parameters, including deuterium occupancy and anisotropic thermal parameters, were determined from high resolution NPD data. The deuterium (and oxygen) occupancy for pre-hydrated BCZY was at its maximum at low temperature and decreased at temperatures greater than 400 °C, even through the phase transition and beyond 600 °C. By contrast, proton diffusion increased with temperature above the phase transition. The combination of both effects, i.e., deuterium content and diffusion coefficient, explains the previous results showing that the proton conductivity dominates the ionic conductivity over the oxygen vacancy mechanism until 600 °C. The phase transition is mainly related to oxygen sublattice relaxation and does not impact the protonic transport mechanism.

Environmental stability remains a major challenge for the commercialisation of organic solar cells and degradation pathways remain poorly understood. Designing materials for improved device stability requires an understanding of the relationship between the properties of the donor or acceptor molecule and different degradation mechanisms. Here we study the correlations between various molecular parameters of the fullerene derivative bis-PCBM and the degradation rate of polymer:bis-PCBM organic solar cells, based on the same carbazole-alt-benzothiadiazole polymer, in aerobic and anaerobic conditions. We compare eight high purity bis-PCBM isomers with different electronic, chemical and packing properties along with PCBM and the mixture of bis isomers. In the case of aerobic photodegradation, we find that device degradation rate is positively correlated to the LUMO energy of the bis-PCBM isomer and to the degree of crystallinity of the isomer, while the correlation of degradation with driving force for epoxide formation is unclear. These results support the idea that in these samples, aerobic photodegradation proceeds via superoxide formation by the photogenerated polaron on the fullerene, followed by further chemical reaction. In the absence of air, photodegradation rate is correlated with molecular structure, supporting the mechanism of microstructural degradation via fullerene dimerization. The approach and findings presented here show how control of specific molecular parameters through chemical design can serve as a strategy to enhance stability of organic solar cells.

Emerging technologies in solar energy will be critical in enabling worldwide society in overcoming the present energy challenges and reaching carbon net zero. Inefficient and unstable charge transport materials limit the current emerging energy conversion and storage technologies. Low-dimensional coordination polymers represent an alternative, unprecedented class of charge transport materials, comprised of molecular building blocks. Here, we provide a comprehensive study of mixed-valence coordination polymers from an analysis of the charge transport mechanism to their implementation as hole-conducting layers. CuII dithiocarbamate complexes afford morphology control of 1D polymer chains linked by (CuI2X2) copper halide rhombi. Concerted theoretical and experimental efforts identified the charge transport mechanism in the transition to band-like transport with a modeled effective hole mass of 6me. The iodide-bridged coordination polymer showed an excellent conductivity of 1 mS cm−1 and a hole mobility of 5.8 10−4 cm2 (V s)−1 at room temperature. Nanosecond selective hole injection into coordination polymer thin films was captured by nanosecond photoluminescence of halide perovskite films. Coordination polymers constitute a sustainable, tunable alternative to the current standard of heavily doped organic hole conductors.

Self-doping organic semiconductors provide a promising route to avoid instabilities and morphological issues associated with molecular n-type dopants. Structural characterization of a naphthalenetetracarboxylic diimide (NDI) semiconductor covalently bound to an ammonium hydroxide group is presented. The dopant precursor was found to be the product of an unexpected base catalyzed hydrolysis, which was reversible. The reversible hydrolysis had profound consequences on the chemical composition, morphology, and electronic performance of the doped films. In addition, we investigated the degradation mechanism of the quaternary ammonium group and the subsequent doping of NDI. These findings reveal that the products of more than one chemical reaction during processing of films must be considered when utilizing this promising class of water-soluble semiconductors.

Circularly polarized organic light-emitting diodes (CP-OLEDs) that demonstrate both state-of-the-art efficiency and strongly circularly polarized (CP) electroluminescence have proved a considerable technical challenge. Furthermore, multiple factors – from film thickness to device structure – have been shown to influence the sign of the emitted CP light, independent of the handedness (absolute stereochemistry) of the chiral emitter. Here we report CP-OLEDs using a blend of poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) and a chiral small molecule additive (1-aza[6]helicene, aza[6]H). We demonstrate CP-OLEDs with an impressive electroluminescence dissymmetry (gEL) > 0.3 and a current efficiency of 0.53 cd A−1 and brightness of 3023 cd m−2. While at low aza[6]H loadings, F8T2 blends are consistent with previous observations of CP dissymetric inversion as a function of film thickness/excitation mode, a higher loading of aza[6]H (∼40 wt%) removes such dependencies while retaining excellent g-factors. The materials disclosed will allow for further mechanistic studies of chiral polymeric materials and provide new opportunities for chiroptical optimisation in films and devices.

Non-equilibrium thermodynamics describe the current–voltage characteristics of electrochemical devices. For conventional electrode–electrolyte interfaces, the local activation overpotential is used to describe the electrostatic potential step between the two materials as a current is generated. However, the activation overpotential for the metal/mixed ionic-electronic conducting (MIEC) composite electrodes studied in this work originates at the MIEC–gas interface. Moreover, we have studied the effects of non-equilibrium on the electrostatic surface potential and evaluated its influence over electrode kinetics. By investigating two phase (2PB) and three phase boundary (3PB) reactions at the Ni/Ce1−xGdxO2−δ (Ni/CGO) electrode, we have demonstrated that the driving force for coupled ion-electron transfer is held at the CGO–gas interface for both reaction pathways. We also determined that the rate of coupled ion-electron transfer via the 3PB scales with the availability of free sites on the metallic surface, revealing a Sabatier-like relationship with regards to the selection of metallic phases. Finally, we demonstrated how the theory of the electrostatic surface potential can be applied to other systems outside of the well-studied H2/H2O electrode environment. These findings therefore provide an insight into the design of future electrode structures for a range of electrochemical devices.

The use of iron-catalysed chain growth of ZnEt2 enables the synthesis of end-functionalised polyethylenes such as PE-I, which can be blended homogeneously into LDPE to affect the polymer degradability.

Nanoconfinement offers opportunities to tune physical properties of molecular entities by altering their assembled structures. This also applies to acene-based molecules with potentially rich π–π interactions. Unlike most of the previous cases with acene-based guests directly incorporated into hosts, we take a further step by oligomerizing a fluorescent anthryl monomer, 9-vinylanthracene, inside nanochannels of a metal–organic framework, which is a pillared three-dimensional kagome net of [Zn2(bdc)2(dabco)] (bdc2– = 1,4-benzenedicarboxylate; dabco = 1,4-diazabicyclo[2.2.2]octane). The fluorescence emission of the guest can be significantly enhanced after oligomerization, which is likely due to the suppressed nonemissive interaction between the oligomerized molecules in the nanospace and the MOF wall. The case we have demonstrated for fluorescence enhancement via confined oligomerization provides inspiration for the design of luminescent composites and is encouraging for further exploration of molecules in a nanoconfined space.

Porous boron nitride (BN) displays promising properties for interfacial and bulk processes, e.g. molecular separation and storage, or (photo)catalysis. To maximise porous BN's potential in such applications, tuning and controlling its chemical and structural features is key. Functionalisation of porous BN with metal nanoparticle represents one possible route, albeit a hardly explored one. Metal–organic frameworks (MOFs) have been widely used as precursors to synthesise metal functionalised porous carbon-based materials, yet MOF-derived metal functionalised inorganic porous materials remain unexplored. Here, we hypothesise that MOFs could also serve as a platform to produce metal-functionalised porous BN. We have used a Cu-containing MOF, i.e. Cu/ZIF-8, as a precursor and successfully obtained porous BN functionalised with Cu nanoparticles (i.e. Cu/BN). While we have shown control of the Cu content, we have not yet demonstrated it for the nanoparticle size. The functionalisation has led to improved light harvesting and enhanced electron–hole separation, which have had a direct positive impact on the CO2 photoreduction activity (production formation rate 1.5 times higher than pristine BN and 12.5 times higher than g-C3N4). In addition, we have found that the metal in the MOF precursor impacts porous BN's purity. Unlike Cu/ZIF-8, a Co-containing ZIF-8 precursor led to porous C-BN (i.e. BN with a large amount of C in the structure). Overall, given the diversity of metals in MOFs, one could envision our approach as a method to produce a library of different metal functionalised porous BN samples.

Flexible strain sensors have attracted considerable attention due to their applications in wearable monitoring fields such as human-computer interaction systems, athletic training, and health systems. Textiles are a desired substrate for fabricating wearable flexible sensors due to their light weight, comfort, and flexibility. However, the compatibility between textiles and conductive materials still faces critical challenges, especially for wearable sensors to achieve high sensitivity and a wide sensing range simultaneously with long-term monitoring stability, reliability, and wearing comfort. In this study, we propose a graphene-based TPU/textile composite sensor that can be produced using small-scale manufacturing techniques, using laser cutting combined with film coating and thermal transfer processes and further explore its mechanical, electrical, and sensing properties. Since the human body exhibits different magnitudes of motion and fabric sensors integrated into clothing would face multiple challenges in real world usage e.g. repetitive wear, sweat and sunlight exposure, we performed sensitivity, reliability and durability tests to further evaluate real world usage of the fabric sensors. The developed composite sensor exhibits a high sensitivity (GF = 498), wide sensing range (0%–293%), excellent reliability and stability which only shows 5% deviation after 10,000 cycles of stretching under 5% strain. In addition, the graphene-based textile composite sensor thermalised by TPU film can also maintain high stability after long-term UV irradiation and multiple washing cycles. When integrated into various wearable devices, our composite sensor can detect a wide range of human body motions accurately, as well as subtle physiological signals, exhibiting great potential in incorporating into wearable monitoring devices.

The mesostructure of porous electrodes used in lithium-ion batteries strongly influences cell performance. Accurate imaging of the distribution of phases in these electrodes would allow this relationship to be better understood through simulation. However, imaging the nanoscale features in these components is challenging. While scanning electron microscopy is able to achieve the required resolution, it has well established difficulties imaging porous media. This is because the flat imaging planes prepared using focused ion beam milling will intersect with the pores, which makes the images hard to interpret as the inside walls of the pores are observed. It is common to infiltrate porous media with resin prior to imaging to help resolve this issue, but both the nanoscale porosity and the chemical similarity of the resins to the battery materials undermine the utility of this approach for most electrodes. In this study, a technique is demonstrated which uses in situ infiltration of platinum to fill the pores and thus enhance their contrast during imaging. Reminiscent of the Japanese art of repairing cracked ceramics with precious metals, this technique is referred to as the kintsugi method. The images resulting from applying this technique to a conventional porous cathode are presented and then segmented using a multi-channel convolutional method. We show that while some cracks in active material particles were empty, others appear to be filled (perhaps with the carbon binder phase), which will have implications for the rate performance of the cell. Energy dispersive X-ray spectroscopy was used to validate the distribution of phases resulting from image analysis, which also suggested a graded distribution of the binder relative to the carbon additive. The equipment required to use the kintsugi method is commonly available in major research facilities and so we hope that this method will be rapidly adopted to improve the imaging of electrode materials and porous media in general.

To realise the promise of solid-state batteries, negative electrode materials exhibiting large volumetric expansions, such as Li and Si, must be used. These volume changes can cause significant mechanical stresses and strains that affect cell performance and durability, however their role and nature in SSBs are poorly understood. Here, a 2D electro-chemo-mechanical model is constructed and experimentally validated using steady-state, transient and pulsed electrochemical methods. The model geometry is taken as a representative cross-section of a non-porous, thin-film solid-state battery with an amorphous Si (a-Si) negative electrode, lithium phosphorous oxynitride (LiPON) solid electrolyte and LiCoO2 (LCO) positive electrode. A viscoplastic model is used to predict the build-up of strains and plastic deformation of a-Si as a result of (de)lithiation during cycling. A suite of electrochemical tests, including electrochemical impedance spectroscopy, the galvanostatic intermittent titration technique and hybrid pulse power characterisation are carried out to establish key parameters for model validation. The validated model is used to explore the peak interfacial (a-Si∣LiPON) stress and strain as a function of the relative electrode thickness (up to a factor of 4), revealing a peak volumetric expansion from 69% to 104% during cycling at 1C. The validation of this electro-chemo-mechanical model under load and pulsed operating conditions will aid in the cell design and optimisation of solid-state battery technologies.

Covalent organic frameworks (COFs) offer a high degree of chemical and structural flexibility. There is a large family of COFs built from 2D sheets that are stacked to form extended crystals. While it has been common to represent the stacking as eclipsed with one repeating layer (“AA”), there is growing evidence that a more diverse range of stacking sequences is accessible. Herein, we report a computational study using density functional theory of layer stacking in two prototypical COFs, Tp-Azo and DAAQ-TFP, which have shown high performance as Li-ion battery electrodes. We find a striking preference for slipped structures with horizontal offsets between layers ranging from 1.7 Å to 3.5 Å in a potential energy minimum that forms a low energy ring. The associated symmetry breaking results in a pronounced change in the underlying electronic structure. A band gap opening of 0.8–1.4 eV is found due to modifications of the underlying valence and conduction band dispersion as explained from changes in the π orbital overlap. The implications for the screening and selection of COF for energy applications are discussed.

We developed a polymer–drug strategy to explore anticancer polymers. A series of monomers containing groups with potential anticancer activity have been facilely prepared through the Biginelli reaction. These monomers were used to produce water-soluble polymers through convenient radical copolymerization. The resulting polymers are biocompatible and can be directly used to suppress proliferation of different cancer cells without the release of small molecules. Theoretical calculations revealed that Biginelli groups in polymers had strong interaction with the Eg5 protein, which is highly expressed in cancer cells and is closely related to cell mitosis. Subsequent cell experiments confirmed that a screened polymer is efficient in inhibiting mitosis in different cancer cells. Our study of exploring functional polymers via the combination of multicomponent reactions and theoretical calculation resulted in promising anticancer polymers, which might pave a path for de novo designing of functional polymers and have important implications in the fields of organic, computational, and polymer chemistry.

TEMPO-oxidised cellulose fibres are often explored as nano-reinforcement for polymers. However, it is unclear whether micrometre-sized TEMPO-oxidised cellulose fibres also possess similar reinforcing potential. In this work, we report the mechanical response of polypropylene (PP) composites reinforced with TEMPO-oxidised cellulose (TOC) of different fibre widths. Micrometre-sized TOC fibres (TOCF) containing sodium carboxylate (TOCF-Na) and free hydroxyl (TOCF-H) groups, as well as nano-sized TOC nanofibrils (TOCN) were produced from dissolving pulp and incorporated into PP matrix via melt-extrusion. It was found that model PP composites containing micrometre-sized TOCF-Na and TOCF-H possessed the highest tensile modulus of up to 2.5 GPa; 40% improvement over neat PP and 30% increase over PP/TOCN composite. No significant differences in the tensile strength of PP/TOCF-Na and PP/TOCF-H composites were observed when compared to neat PP. The incorporation of nano-sized TOCN into PP however, led to a 6% decrease in tensile strength. Single-edge notched beam fracture toughness test further showed that PP/TOCN composite possessed the lowest fracture toughness of 2.52 MPa m1/2; a decrease of 18% over PP reinforced with micrometre-sized TOCF-Na and TOCF-H. Our study shows that micrometre-sized TOCFs serve as better reinforcement for polymers compared to nano-sized TOCN. This is attributed to the better dispersion of TOCF in the PP matrix. Furthermore, the presence of surface microfibrillation on TOCFs also enhanced the quality of the TOCF-PP interface through mechanical interlocking and local stiffening of the PP matrix.

Pb-based halide perovskites have recently showed great potential in various applications such as solar cells, optoelectronics and photocatalysis. Despite their high performance, the Pb2+ toxicity along with poor stability hinders long term applications in photocatalysis. Herein, we report mechanochemically prepared Pb-free Cs2AgBiBr6 double perovskite nanoplates and their heterostructure with Cu-loaded reduced graphene oxide (Cu–RGO) for gas-phase photocatalytic CO2 reduction using water vapor as the proton source in the absence of a hole scavenger. The resulting Cs2AgBiBr6–Cu–RGO nanocomposite shows significant photocatalytic activity of 10.7 (±0.6) μmol CH4 g−1 h−1, 1.9 (±0.3) μmol CO g−1 h−1 and 1.0 (±0.2) μmol H2 g−1 h−1, with a CH4 selectivity of 93.0 (±0.5)% on an electron basis with 1 sun and a remarkable apparent quantum efficiency of 0.89 (±0.21)% at 590 nm. A further 32% enhancement in photocatalytic activity on an electron basis is achieved when the light intensity is doubled (2 suns). The high performance was attributed to their improved charge separation and suppressed electron–hole recombination, along with extended visible light absorption, better stability in a humid environment and improved CO2 adsorption. These findings support Cs2AgBiBr6 as a potential Pb-free alternative to conventional halide perovskites for photocatalytic solar-to-fuel conversion and CO2 utilization.

In the search for high performance n-type organic semiconductors (OSCs) a simple strategy might be substitution of aromatic CH groups for nitrogen heteroatoms. Here, we report the synthesis and characterisation of two novel N-heteroacene compounds, namely, 1,5,12-triazatetracene (TrAT1) and 2,5,12-triazatetracene (TrAT2). Their potential as n-type materials is evaluated against 5,12-diazatetracene (DAT) by UV/vis and EPR spectroscopy, cyclic voltammetry, DFT, single crystal X-ray diffraction and thin film characterisation. Increasing the number of N-heteroatoms was found to stabilise the HOMO and LUMO leading to electron affinities for TrAT1 and TrAT2 of ca. −4 eV. Both compounds were found to exhibit columns of co-facial π-stacked molecules. For TrAT1, molecules are also linked by hydrogen bonding, while the crystal structure of TrAT2 was found to be inherently disordered. Thin films of DAT, TrAT1 and TrAT2 were grown by organic molecular beam deposition (OMBD) and found to form discontinuous films, where TrAT1 exhibited a preferential orientation.

Substituted SrCoO3 perovskites have been proposed as promising mixed ionic electronic conductors for a range of applications including intermediate temperature solid oxide fuel cells (IT-SOFCs), electrolysers and thermochemical water splitting reactors for H2 production. In this work we investigate the effect of sample exposure to water in substituted SrCoO3 powders and thin films and correlate it with the degradation of oxygen mobility and kinetics. SrCo0.95Sb0.05O3−δ (SCS) thin films have been deposited on different single crystal substrates by pulsed laser deposition (PLD). After water cleaning and post annealing at 300 °C, the sample surface presented an increase of the SrO-surface species as observed by ex situ X-ray Photoemission Spectroscopy (XPS) analysis. This increase in SrO at the sample surface has also been confirmed by the Low Energy Ion Scattering (LEIS) technique on both SCS thin film and powder. Thermochemical water splitting experiments on SCS and SrCo0.95Mo0.05O3−δ (SCM) powder revealed a phase degradation under water oxidising conditions at high temperature with the formation of the trigonal phase Sr6Co5O15. Transmission Electron Microscopy (TEM) analysis of SCS powder treated with water suggests that this phase degradation could already superficially start at Room Temperature (RT). By isotope exchange depth profile experiments on SCS thin films, we were able to quantify the oxygen diffusivity in this SCS surface decomposed layer (D* = 5.1 × 10−17 cm2 s−1 at 400 °C). In the specific case of bulk powder, the effect of water superficial decomposition translates into a lower oxidation and reduction kinetics as demonstrated by comparative thermogravimetric analysis (TGA) studies.

With the emergence of stretchable/wearable devices, functions, such as sensing, energy storage/harvesting, and electrical conduction, should ideally be carried out by a single material, while retaining its ability to withstand large elastic deformations, to create compact, functionally-integrated and autonomous systems. A new class of trimodal, stretchable yarn-based transducer formed by coating commercially available Lycra® yarns with PEDOT:PSS is presented. The material developed can sense strain (first mode), and temperature (second mode) and can power itself thermoelectrically (third mode), eliminating the need for an external power-supply. The yarns were extensively characterized and obtained an ultrahigh (gauge factor ∼3.6 × 105, at 10–20% strain) and tunable (up to about 2 orders of magnitude) strain sensitivity together with a very high strain-at-break point (up to ∼1000%). These PEDOT:PSS-Lycra yarns also exhibited stable thermoelectric behavior (Seebeck coefficient of 15 μV K−1), which was exploited both for temperature sensing and self-powering (∼0.5 μW, for a 10-couple module at ΔT ∼ 95 K). The produced material has potential to be interfaced with microcontroller-based systems to create internet-enabled, internet-of-things type devices in a variety of form factors.

Ionogels are emerging as soft materials with remarkable physical properties that can be tuned to suit application requirements. The liquid component—ionic liquids—are effectively involatile, which provides new opportunities to explore gel surfaces with UHV based analytical techniques. Here, we exploit the highly solvating nature of ionic liquids to fabricate poly(ethylene glycol) based ionogels with high concentrations of zinc, and then investigate their surfaces to show that tunability extends beyond the bulk to the interface. A unique relationship between Lewis acidity and basicity and the surface concentration of metal was revealed. Chemical state analysis and molecular dynamics showed that Lewis acidic metals templated polymers to give new architectures reduced brittleness and increased flexibility, while Lewis basic metals improved polymer uniformity and strengthened gels. Therefore, bulk structure, surface composition, and metal speciation were all found to be intimately related and dependent upon the coordination strengths of ionic liquid anions. Importantly, the highly controllable surface and structural properties of metal ionogels allow fine-tuning across a broad design space, which presents new opportunities for gel based applications.

We report the mechanism of rhodamine B (RhB) acting as an electrolyte additive in Li/graphite cells. We show that the cycle performance and rate capability of graphite are enhanced in carbonate-based electrolytes containing 0.2 wt% RhB. By using silica-encapsulated Au nanoparticles, in situ surface-enhanced Raman spectroscopy (SERS) is applied to study the graphite/electrolyte interface. We find that the adsorption orientation of RhB molecules on the surface of graphite can be modulated by the applied potential: vertical adsorption at higher potentials while horizontal adsorption takes place at lower potentials. This behavior effectively suppresses the electrolyte solvent decomposition, as well as electrode corrosion while improving the Li+ diffusion. This work shows that SERS is a powerful tool for interfacial analysis of battery systems and provides new ideas for rational design of electrolyte additives., In situ surface-enhanced Raman spectroscopy reveals that the adsorption orientation of rhodamine B on the surface of graphite is modulated by the applied potential, drastically altering the cycle performance and rate capability of Li/graphite cells.

Thermoresponsive polymers based on oligo(ethylene glycol) (OEG) methyl ether methacrylate monomers have drawn much attention in recent years. In this investigation, copolymers based on oligo(ethylene glycol) methyl ether methacrylate (OEGMA, 300 g mol-1) and di(ethylene glycol) methyl ether methacrylate (DEGMA) or/and n-butyl methacrylate (n-BuMA) were successfully synthesised via group transfer polymerisation (GTP). The molar mass was kept constant around 10000 g mol-1, while the OEGMA content was varied from 80% w/w to 50% w/w. Three different structures including diblock bipolymer, diblock terpolymer and statistical copolymers were synthesised and compared. The thermoresponsive properties of the copolymers were investigated in deionised water and phosphate buffered saline (PBS), and in aqueous mixtures with Pluronic® F127. Interestingly, while the diblock polymers based on OEGMA and DEGMA were not able to form gel upon heating, they were found to lower the critical gelation concentration (CGC) of Pluronic® F127 from 15% w/w to 10% w/w and increase the gelation temperature from room temperature to near body temperature.

The use of perovskite materials for thermochemical energy storage and oxygen separation has been gaining momentum in recent years due to their ability to topotactically exchange large volumes of oxygen, and their chemical and structural flexibility. B-site substituted SrCoO3-δ derivatives have previously been investigated as promising materials for intermediate temperature solid oxide fuel cell cathodes due to the stabilization of a 3 C perovskite structure with high electronic and ionic conductivity that allows large oxygen storage capabilities. Here, antimony-substituted strontium cobalt oxides are investigated and identified as new candidate materials for thermochemical oxygen separation applications. In this work we shed light on the exceptional redox kinetics and cyclability of antimony-substituted variants undergoing oxygen exchange at intermediate temperatures (500 to 800 °C). Through the use of density functional theory and isothermal gas atmosphere switching, we demonstrate how the inductive effect of the more electronegative antimony dopants in the Co position, facilitates the kinetics of metal oxide oxidation, whilst hindering reduction reactions. SrCo0.95Sb0.05O3−δ was identified to isothermally evolve 3.76 cm3 g−1 of oxygen at 500 °C and calculated to produce up to 10.44 cm3 g−1 under temperature-swing reaction configurations aligning with previously reported materials.

Amongst the greatest challenges in developing injectable controlled thermoresponsive micellar and hydrogel drug delivery vehicles include tuning the cloud point (CP) and reducing the gelation temperature (Tgel), below 37 °C, without compromising stability and solubility. Here, a unique strategy is employed using ionic liquid (IL) matrices to produce stable micellar and hydrogel delivery vehicles of distinct thermoresponsive properties. Each formulation includes the in-house synthesised polymer OEGMA30020-b-BuMA22-b-DEGMA11 with FITC-IgG. Both micellar-IL and hydrogel-IL formulations exhibit enhanced stability following 120 days of storage under 4 °C compared to in phosphate buffered saline (PBS). Visual tests demonstrate that the CP of the micellar-IL carriers can be finely tuned (31- 46 °C). Rheology measurements show that hydrogel strength is significantly increased and Tgel is reduced, from 40 °C in PBS to 30 °C with IL. Finally, a unique stabilisation mechanism is proposed, triggered by the synergetic action of the excipients and IL in each system

The comment of Díez-García and co-workers on the article ‘Flat band potential determination: avoiding the pitfalls’ is a very valuable contribution to the discussion about the appropriateness of various models and techniques used for the determination of flat band potentials of semiconducting photoelectrodes, as well as other parameters. Such discussions will benefit the community and should improve the reliability of published parameters characterising photoelectrode interfaces with electrolytes. Herein we respond to the specific topics addressed in the comment: (i) the correction of the geometric photoelectrode surface area by surface roughness to enable more accurate characterisation of materials with nanotextured surfaces and (ii) the inclusion of photon flux limitation in the Gärtner–Butler model.

In the February issue of Chem, Hu, Wang, and coworkers synthesized a Janus metal-organic layer that can be embedded into lipid bilayer membranes, undergoes photo-induced charge transfer, and facilitates active H+ transport and subsequent ATP synthesis by CF0F1-ATP synthase in liposomes.

Detergents are widely used for membrane protein solubilization, purification, and structural analysis. Over the past two decades, much effort has been made to design novel detergents with improved properties. Here, we provide the details of 23 different classes of novel detergents with particular focus on OGNG, LMNG, and GDN, which have been widely applied to the successful determination of a wide range of membrane protein structures. This review provides insights into the biophysical basis of the distinct behaviors of these three detergents by analysis of the stability of protein-detergent complexes (PDCs) in terms of detergent-detergent and detergent-protein interactions. The review also discusses recently developed variants of OGNG, LMNG, and GDN as well as several other classes of amphiphiles in the context of these interactions. Finally, a detailed perspective of a new detergent design is provided as a basis for expanding the applicability of small detergents for membrane protein structural study.

Silicon/graphite blended electrodes are promising candidates to replace graphite in lithium ion batteries, benefiting from the high capacity of silicon and the good structural stability of carbon. Models have proven essential to understand and optimise batteries with new materials. However, most previous models treat silicon/graphite blends as a single “lumped” material, offering limited understanding of the behaviors of the individual materials and thus limited design capability. Here, we present a multi-material model for silicon/graphite electrodes with detailed descriptions of the contributions of the individual active materials. The model shows that silicon introduces voltage hysteresis to silicon/graphite electrodes and consequently a “plateau shift” during delithiation of the electrodes. There will also be competition between the silicon and graphite lithiation reactions depending on silicon/graphite ratio. A dimensionless competing factor is derived to quantify the competition between the two active materials. This is demonstrated to be a useful indicator for active operating regions for each material and we demonstrate how it can be used to design cycling protocols for mitigating electrode degradation. The multi-material electrode model can be readily implemented into full-cell models and coupled with other physics to guide further development of lithium ion batteries with silicon-based electrodes.

Summary The genesis of anion receptor chemistry can be traced back to the late 1960s with the work of Shriver and Biallas on chelating Lewis acids and Park and Simmons on ammonium-containing cryptand-like halide receptors. Despite pioneering work in the 1970s and 1980s from the groups of Lehn and Schmidtchen, the area did not attract significant interest until the 1990s, when the field of anion receptor chemistry—which includes molecular recognition, sensing, transmembrane anion transport, extraction, crystal engineering, self-assembly, and catalysis—began to blossom. This Perspective highlights the recent developments in this area and examines future challenges.

Single-molecule pulling experiments are widely used to extract both thermodynamic and kinetic data on ligand-receptor pairs, typically by fitting different models to the probability distribution of rupture forces of the corresponding bond. Here, a theoretical model is presented that shows how a measurement of the number of binding and unbinding events as a function of the observation time can also give access to both the binding (kon) and the unbinding (koff) rates of bonds, which combined provide a well-defined bond free-energy ΔGbond. The connection between ΔGbond and the ligand-receptor binding constant measured by typical binding essays is critically discussed. The role played by the molecular construct used to tether ligands and receptors to a surface is considered, highlighting the various approximations necessary to derive general expressions that connect its structure to its contribution, termed ΔGcnf, to the bond free-energy. In this way, the validity and the assumptions underpinning widely employed formulas and experimental protocols used to extract binding constants from single-molecule experiments are assessed. Finally, the role of ΔGcnf in processes mediated by ligand-receptor binding is briefly considered, and an experiment to unambiguously measure this quantity proposed.

The rigid cellular materials widely used for personal impact protection can be effective but tend to be inconveniently thick, and to be less effective after a first impact. A macroscopically structured panel material, molded as a two‐dimensional matrix of re‐entrant cells, has been specifically designed and optimized for body‐worn protection. These panels are injection molded from a blend of rate‐stiffening polyborodimethylsiloxane with a thermoplastic elastomer, optimized to minimize the impact force transmitted to the anvil in standard drop‐weight tests even as monolithic slab specimens. The concurrently designed, impact‐protective molded panels offer equivalent protection in thinner, lighter, and more wearable layers. Their re‐entrant cellular structure and rate‐stiffening material allow them to conform easily to individual wearers and to allow free movement at normal rates, while offering enhanced protection under one or more impacts at the same location.

We report the electronic structure of two metal-organic frameworks (MOFs) with copper paddle wheel nodes connected by a N2(C2H4)3 (DABCO) ligand with accessible nitrogen lone pairs. The coordination is predicted, from first-principles density functional theory, to enable electronic pathways that could facilitate charge carrier mobility. Calculated frontier crystal orbitals indicate extended electronic communication in DMOF-1, but not in MOF-649. This feature is confirmed by bandstructure calculations and effective masses of the valence band egde. We explain the origin of the frontier orbitals of both MOFs based on the energy and symmetry alignment of the underlying building blocks. The effects of doping on the bandstructure of MOF-649 are considered. Our findings highlight DMOF-1 as a potential semiconductor with 1D charge carrier mobility along the framework

In the development of high temperature electrochemical devices such as oxygen transport membranes (OTMs) and solid oxide fuel cells (SOFCs), solid-state (ceramic) technologies have proven to be particularly promising. For example, doped lanthanum chromite perovskites, which display high thermo-chemical stability in aggressive environments as mixed ionic and electronic conducting (MIEC) perovskite electrodes, show potential for use as OTMs. Previous studies on the range of these MIEC perovskites have focussed on material behaviour under pure oxygen conditions. Recently, however, it has been suggested that components of air such as humid vapour may modify the materials' chemistry under device operating conditions, affecting device performance and durability. We have designed and carried out fundamental research into the effect of humidity on the oxygen surface exchange and diffusion kinetics of a commercialized (La0.8Sr0.2)0.95Cr0.5Fe0.5O3−δ (LSCrF8255) perovskite material under elevated OTM and SOFC operating conditions. The water surface exchange and oxygen ion diffusion behaviour of LSCrF8255 perovskites were measured through Isotopic Exchange Depth Profiling-Secondary Ion Mass Spectrometry (IEDP-SIMS) in a designed humid condition with an oxygen partial pressure of 200 mbar and a constant water vapour pressure of 30 mbar, from intermediate to high temperatures (600 °C to 900 °C). Our study demonstrates consistency between oxygen ion bulk diffusion kinetics in wet (pO2 = 200 mbar, pH2O = 30 mbar) and dry (pO2 = 200 mbar, pH2O = 0 mbar) oxygen atmospheres. However, limited surface exchange between water and the LSCrF material was observed above 800 °C. To study the limited water surface exchange behaviour, angle-resolved X-ray photoelectron spectroscopy (ARXPS), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM) have been applied to correlate the changes in water surface exchange with chemical or topographic changes in the materials, such as Sr surface segregation processes. It was found that Sr segregation is one of the factors suppressing water surface exchange, although not the primary limiting factor. Another limiting factor was found through in situ residual gas analysis (RGA), which showed the dominance of homo-exchange between the humid vapour and gaseous oxygen molecules at high temperatures.

A novel auto-catalytic reaction, a combination of naturally occurring enzyme glucose oxidase (GOx) and amine-functionalised cerium oxide nanoparticles (nanoceria), was employed for open vessel free radical polymerisation of double network hydrogels (DNHGs). The nanoceria also incorporated into the gels to enhance mechanical strength. GOx reduces atmospheric O2 to H2O2, causing a cyclic change of cerium ion states, resulting in propagating free radicals in the carbon group in the amino functionalised nanoceria surface. We synthesised novel nanocomposite DNHGs by grafting polymers onto amine-functionalised nanoceria (ANC), with poly(2-acrylamido-2-methylpropanesulfonic acid), PAMPS, and polyacrylamide (PAAm) in the first and second networks respectively. The graft polymerisation was initiated using the alternating cerium states on the ANC. GOx held two major roles within the reaction: to provide an oxygen free system, without any other form of degassing, and to provide cyclical cerium ion states between Ce4+ and Ce3+, creating new free radicals for polymerisation. Polymer conversion using ANC as the sole initiator in the presence of GOx resulted in 83% conversion for PAMPS and 64% PAAm. Polymers degassed only with argon resulted in less than 55% conversion for both PAAm and PAMPS, proving that the addition of GOx enhanced the reaction. The new gels (1.76 MPa) showed an order of magnitude improvement in mechanical properties compared to DNHG made without ANC/GOx (0.10 MPa).

Doped-ZnO nanoparticles, capped with dioctylphosphinate ligands, are synthesised by the controlled hydrolysis of a mixture of organometallic precursors. Substitutional doping of the wurtzite ZnO nanoparticles with 5 mol% Mg(II), Al(III) and Cu(I) is achieved by the addition of sub-stoichiometric amounts of the appropriate dopant [(n-butyl)(sec-butyl)magnesium, triethylaluminium or mesitylcopper] to diethylzinc in the precursor mixture. After hydrolysis, the resulting colloidal nanoparticles (sizes of 2–3 nm) are characterised by powder X-ray crystallography, transmission electron microscopy, inductively-coupled plasma optical emission spectrometry and X-ray photoelectron spectroscopy. A solution of the doped-ZnO nanoparticles and colloidal Cu(0) nanoparticles [M:ZnO : Cu = 1 : 1] are applied as catalysts for the hydrogenation of CO2 to methanol in a liquid-phase continuous flow stirred tank reactor [210 °C, 50 bar, CO2 : H2 = 1 : 3, 150 mL min−1, mesitylene, 20 h]. All the catalyst systems display higher rates of methanol production and better stability than a benchmark heterogeneous catalyst, Cu–ZnO–Al2O3 [480 μmol mmolmetal−1 h−1], with approximately twice the activity for the Al(III)-doped nanocatalyst. Despite outperforming the benchmark catalyst, Mg(II) doping is detrimental towards methanol production in comparison to undoped ZnO. X-Ray photoelectron spectroscopy and transmission electron microscopy analysis of the most active post-catalysis samples implicate the migration of Al(III) to the catalyst surface, and this surface enrichment is proposed to facilitate stabilisation of the catalytic ZnO/Cu interfaces.