Solar redox flow batteries (SRFB) have received much attention as an alternative integrated technology for simultaneous conversion and storage of solar energy. Yet, the photocatalytic efficiency of semiconductor-based single photoelectrodes, such as hematite, remains low due to the trade-off between fast electron hole recombination and insufficient light utilization, as well as inferior reaction kinetics at the solid/liquid interface. Herein, we present an α-FeO/Cu O p-n junction, coupled with a readily scalable nanostructure, that increases the electrochemically active sites and improves charge separation. Thanks to light-assisted scanning electrochemical microscopy (photo-SECM), we elucidate the morphology-dependent carrier transfer process involved in the photo-oxidation reaction at an α-FeO photoanode. The optimized nanostructure is then exploited in the α-FeO/Cu O p-n junction, achieving an outstanding unbiased photocurrent density of 0.46 mA cm, solar-to-chemical (STC) efficiency over 0.35% and a stable photocharge-discharge cycling. The average solar-to-output energy efficiency (SOEE) for this unassisted α-FeO-based SRFB system reaches 0.18%, comparable to previously reported DSSC-assisted hematite SRFBs. The use of earth-abundant materials and the compatibility with scalable nanostructuring and heterojunction preparation techniques offer promising opportunities for cost-effective device deployment in real-world applications.

The electroreduction of CO (CORR) is a promising alternative to the direct CO electroreduction reaction (CO2RR) to produce C products. Cu-based electrocatalysts enable the formation of C-C bonds, leading to various C hydrocarbon and oxygenate products. Herein, we investigated how the composition of bimetallic Cu-Ag catalysts impacted the nature of the Cu-Ag interactions and the product distribution of the CORR, aiming to improve the selectivity to C products. Cu-Ag catalysts containing 1-50 mol% Ag were prepared by sol-gel synthesis. A Ag content of 10 mol% of Ag (CuAg) was optimum with respect to increasing the C product selectivity and suppressing H evolution. X-ray absorption spectroscopy and quasi- X-ray photoelectron spectroscopy demonstrated the complete reduction of CuO to Cu during CORR. Electron microscopy (EM) and wide-angle X-ray scattering (WAXS) revealed substantial restructuring during reduction. EM imaging showed the formation of Ag-Cu core-shell structures in CuAg, while separate Cu and Ag particles were predominant at higher Ag content. WAXS revealed the formation of a Cu-Ag nanoalloy phase in the bimetallic Cu-Ag samples. The optimum CuAg sample contained more Cu-Ag nanoalloys than samples with a higher Ag content. The Cu-Ag interfaces between the Ag-core and the Cu-shell in the bimetallic particles are thought to host the nanoalloys. The optimum CORR performance for CuAg is likely due to the enhanced Cu-Ag interactions, as confirmed by a sample prepared with the same surface composition by galvanic exchange.

Battery research often encounters the challenge of determining chemical information, such as composition and elemental oxidation states, of a layer buried within a cell stack in a non-destructive manner. Spectroscopic techniques based on X-ray emission or absorption are well-suited and commonly employed to reveal this information. However, the attenuation of X-rays as they travel through matter creates a challenge when trying to analyze layers buried at depths exceeding hundred micrometers from the sample's surface. In the context of battery research, the limited escape depth of X-rays often necessitates the design of experiment-specific cells with thinner inner layers, despite the risk that these tailored cells may not exactly replicate the cycling behavior of larger commercial cells. Muon-induced X-ray emission (MIXE) is a non-destructive spectroscopic technique that involves implanting negative muons into a sample and detecting the highly energetic muonic X-rays generated when these muons are captured by the sample's atoms. By virtue of the high energy of muonic X-rays, the depth of analysis of MIXE greatly exceeds that of other X-ray based techniques. In this article, we introduce the technique and lay the groundwork for employing MIXE in future / analyses of batteries. We demonstrate that MIXE can detect nearly all elements, including low atomic number ones such as Li. Additionally, we establish the quantitative nature of MIXE through the precise determination of LiNi Mn Co O (NMC) electrode stoichiometries. Finally, we demonstrate that MIXE enables the acquisition of depth-resolved chemical information from a 700 μm thick cell, in good agreement with simulation results.

Zinc ferrite (ZnFeO, ZFO) has gained attention as a candidate material for photoelectrochemical water oxidation. However, champion devices have achieved photocurrents far below that predicted by its bandgap energy. Herein, strong optical interference is employed in compact ultrathin film (8-14 nm) Ti-doped ZFO films deposited on specular back reflectors to boost photoanode performance through enhanced light trapping, resulting in a roughly fourfold improvement in absorption as compared to films deposited on transparent substrates. The spatial charge carrier collection profile and wavelength-dependent photogeneration yield of mobile charge carriers was then extracted spatial collection efficiency analysis based on optical and external quantum efficiency measurements. We demonstrate that despite the enhanced performance enabled by the light trapping structure, substantial recombination occurs for thin film ZFO photoanodes even within the space charge region of an ultrathin film photoanode. Furthermore, the excitation-wavelength-dependent yield of mobile charge carriers in ZFO is shown to be less than unity across the visible spectrum, ultimately limiting the attainable photocurrent density. These results explain the underperformance of ZFO as a photoanode material and suggest that reduction of the mobile charge carrier yield due to the existence of ligand field states is a dominant loss mechanism for metal-oxides containing Fe metal centers with open d-shell configuration.

Solid-state batteries currently receive ample attention due to their potential to outperform lithium-ion batteries in terms of energy density when featuring next-generation anodes such as lithium metal or silicon. One key remaining challenge is identifying solid electrolytes that combine high ionic conductivity with stability in contact with the highly reducing potentials of next-generation anodes. Fully reduced electrolytes, based on irreducible anions, offer a promising solution by avoiding electrolyte decomposition altogether. In this study, we demonstrate the compositional flexibility of the disordered antifluorite framework accessible by mechanochemical synthesis and leverage it to discover irreducible electrolytes with high ionic conductivities. We show that the recently investigated LiNCl and LiNCl phases are part of the same solid solution of Li-deficient antifluorite phases existing on the LiCl-LiN tie line with a general chemical formula of Li Cl N (0.33 < < 0.5). Using density functional theory calculations, we identify the origin of the 5-order-of-magnitude conductivity increase of the Li Cl N phases compared to the structurally related rock-salt LiCl phase. Finally, we demonstrate that S- and Br-substituted analogues of the Li Cl N phases may be synthesized, enabling significant conductivity improvements by a factor of 10, reaching 0.2 mS cm for LiSBrN. This investigation demonstrates for the first time that irreducible antifluorite-like phases are compositionally highly modifiable; this finding lays the ground for discovery of new compositions of irreducible antifluorite-like phases with even further increased conductivities, which could help eliminate solid-electrolyte decomposition and decomposition-induced Li losses on the anode side in high-performance next-generation batteries.

The advancement of rapid-response grid energy storage systems and the widespread adoption of electric vehicles are significantly hindered by the charging times and energy densities associated with current lithium-ion battery technology. In state-of-the-art lithium-ion batteries, graphite is employed as the standard negative electrode material. However, graphite suffers from polarization and deteriorating side-reactions at the high currents needed for fast charging. Transition metal-oxide anodes are attractive alternatives due to their enhanced power density. However, often these anodes make use of toxic or scarce elements, significantly limiting their future potential. In this work, we propose a new, facile solid-state synthesis method to obtain non-toxic, abundant, mixed-phase copper niobate (Cu Nb O ) anodes for lithium-ion batteries. The material consists of various phases working synergistically to deliver high electrochemical capacities at exceptional cycling rates (167 mA h g at 1C, 95 mA h g at 10C, 65 mA h g at 60C and 37 mA h g at 250C), large pseudocapacitive response (up to 90%), and high Li diffusion coefficient (1.8 × 10 cm s), at a stable capacity retention (99.98%) between cycles. Compared to graphite, at a comparable energy density (470 W h L), the composite material exhibits a 70 times higher power density (27 000 W L). These results provide a new perspective on the role of non-toxic and abundant elements for realizing ultrafast anode materials for future energy storage devices.

The catalytic and plasmonic properties of bimetallic gold-palladium (Au-Pd) nanoparticles (NPs) critically depend on the distribution of the Au and Pd atoms inside the nanoparticle bulk and at the surface. Under operating conditions, the atomic distribution is highly dynamic. Analyzing gas induced redistribution kinetics at operating temperatures is therefore key in designing and understanding the behavior of Au-Pd nanoparticles for applications in thermal and light-driven catalysis, but requires advanced characterization strategies. In this work, we achieve the analysis of the gas dependent alloying kinetics in bimetallic Au-Pd nanoparticles at elevated temperatures through a combination of CO-DRIFTS and gas-phase transmission electron microscopy (TEM), providing direct insight in both the surface- and nanoparticle bulk redistribution dynamics. Specifically, we employ a well-defined model system consisting of colloidal Au-core Pd-shell NPs, monodisperse in size and uniform in composition, and quantify the alloying dynamics of these NPs in H and O under isothermal conditions. By extracting the alloying kinetics from TEM measurements, we show that the alloying behavior in Au-Pd NPs can be described by a numerical diffusion model based on Fick's second law. Overall, our results indicate that exposure to reactive gasses strongly affects the surface composition and surface alloying kinetics, but has a smaller effect on the alloying dynamics of the nanoparticle bulk. Both our methodology as well as the quantitative insights on restructuring phenomena can be extended to a wider range of bimetallic nanoparticle systems and are relevant in understanding the behavior of nanoparticle catalysts under operating conditions.

We herein report on a fast and convenient soft-chemical synthesis approach towards large 1T-CrTe van-der-Waals crystals. This compound is formed X-ray diffraction pure, with a complete conversion within just over 2 h from flux-grown LiCrTe crystals using diluted acids. Due to the availability of high-quality single crystals, we have confirmed the crystal structure for the first time by single-crystal X-ray diffraction experiments. For the acid deintercalated 1T-CrTe crystals, we find long-range ferromagnetic order with a Curie temperature of = 318 K. We further revealed the magnetic structure of 1T-CrTe using low-temperature neutron powder diffraction experiments and determined the magnetic Hamiltonian using density functional theory. X-ray diffraction experiments of post-annealed crystals suggest a thermal stability of 1T-CrTe up to at least 100 °C. Our findings expand the synthesis methods for 1T-CrTe crystals, which hold promise for integrated room-temperature spintronics applications.

Covalent organic frameworks (COFs) have developed as efficient and selective adsorbents to mitigate TcO contamination. However, the eco-friendly and scalable production of COF-based adsorbents for the removal of TcO has not yet been reported. This study explores the potential of a cationic COF (TpDB-COF) synthesized a green hydrothermal method, achieving gram-scale yields per batch, thereby addressing a significant limitation of existing COF production methods. The TpDB-COF demonstrates an exceptional stability in strongly acidic conditions (2 weeks in 3 M HNO), as well as in various organic solvents, making it suitable for harsh nuclear waste environments. Adsorption experiments using ReO as a surrogate for TcO show rapid adsorption kinetics, reaching nearly 100% removal efficiency within 1 min (with initial concentration of 28 ppm at a solid-to-liquid ratio of 1 g L), a maximum adsorption capacity of 570 mg g and excellent stability. Moreover, the COF maintains high selectivity for ReO even in the presence of competing anions such as SO and NO . These findings highlight that the hydrothermal synthesis is an effective method to synthesize COF adsorbents for efficient removal of TcO and offers a sustainable approach for practical applications.

Electrolyzers operate over a range of temperatures; hence, it is crucial to design electrocatalysts that do not compromise the product distribution unless temperature can promote selectivity. This work reports a synthetic approach based on electrospinning to produce NiO:SnO nanofibers (NFs) for selectively reducing CO to formate above room temperature. The NFs comprise compact but disjoined NiO and SnO nanocrystals identified with STEM. The results are attributed to the segregation of NiO and SnO confirmed with XRD. The NFs are evaluated for the CO reduction reaction (CORR) over various temperatures (25, 30, 35, and 40 °C). The highest faradaic efficiencies to formate (FE ) are reached by NiO:SnO NFs containing 50% of NiO and 50% SnO (NiOSnO50NF), and 25% of NiO and 75% SnO (NiOSnO75NF), at an electroreduction temperature of 40 °C. At 40 °C, product distribution is assessed with differential electrochemical mass spectrometry (DEMS), recognizing methane and other species, like formate, hydrogen, and carbon monoxide, identified in an electrochemical flow cell. XPS and EELS unveiled the FE variations due to a synergistic effect between Ni and Sn. DFT-based calculations reveal the superior thermodynamic stability of Ni-containing SnO systems towards CORR over the pure oxide systems. Furthermore, computational surface Pourbaix diagrams showed that the presence of Ni as a surface dopant increases the reduction of the SnO surface and enables the production of formate. Our results highlight the synergy between NiO and SnO, which can promote the electroreduction of CO at temperatures above room temperature.

BaNbMoO-based hexagonal perovskite derivatives are promising oxygen-ion conductors for solid electrolytes in solid-oxide fuel cells and electrolysers. A thorough understanding of chemical substitution and its impact on structural features conducive to high ionic conductivity is fundamental for decreasing the operation temperature of such devices. Here, a new 7H polytype-based composition, namely BaNb V MoO, is investigated to assess the effect of vanadium substitution. Structural changes upon V incorporation are studied using X-ray and neutron diffraction, as well as V and Nb solid-state nuclear magnetic resonance spectroscopy. For the undoped composition at room temperature, two distinct oxygen sites (O1 and O5) are found along the palmierite-like layer, corresponding to a mix of four- and six-fold coordination for adjacent M2 cations. At high temperature (527 °C), reorganization of oxygen results in the major occupation of O1 and four-fold (tetrahedral) coordination of the M2 cations. The same rearrangement is observed upon V-substitution, but already at room temperature. From V NMR, we identified a tetrahedral coordination for V cations, indicating their preferential occupation of the M2 site. This preferential occupation by V cations is correlated with increasing tetrahedral coordination of Nb cations as observed from Nb NMR. Altogether, these observations indicate that V-substitution impacts the oxygen sublattice so as to mimic the high-temperature structure. Additionally, BVSE calculations demonstrate a decreasing energy barrier for O migration associated with the presence of vanadium in the structure. This conclusion corroborates the hypothesis that vanadium's propensity for a lower coordination number is beneficial for promoting high O mobility in this promising class of oxide-ion conductors.

Molecular solar thermal systems, which absorb light, store it, and release it as heat, have been extensively researched, yet many potential candidates remain unexplored. To expand this range, five specifically designed -dianthrylbenzenes were investigated. Anthracene dimers have been underexplored due to issues like photooxidation and varying photodimerization efficiency. The presented systems address these challenges by aryl-linking two anthracene moieties, achieving photodimerization quantum yields ranging from 11.5% to 16% in mesitylene. The impact of donor or acceptor groups on energy storage time (9-37 years), energy storage density (0.14-0.2 MJ kg), and solar energy storage efficiency (0.38-0.66%) was evaluated. The experimental results, supported by density functional theory-based modeling, highlight the potential of anthracene-based photoswitches for molecular solar thermal applications and encourage further exploration of similar systems.

[This corrects the article DOI: 10.1039/D4TA03165B.].

Understanding diffusion mechanisms in solid electrolytes is crucial for advancing solid-state battery technologies. This study investigates the role of structural disorder in Li PS Br argyrodites using molecular dynamics, focusing on the correlation between key structural descriptors and Li-ion conductivity. Commonly suggested parameters, such as configurational entropy, bromide site occupancy, and bromine content, correlate with Li-ion diffusivity but do not consistently explain conductivity trends. We find that a uniform distribution of bromine and sulfur ions across the 4a and 4d sublattices is critical for achieving high conductivity by facilitating optimal lithium jump activation energies, anion-lithium distances, and charge distribution. Additionally, we introduce the ionic potential as a simple descriptor that predicts argyrodite conductivity by assessing the interaction strength between cations and anions. By analyzing the correlation between ionic potential and conductivity for a range of argyrodite compositions published over the past decade, we demonstrate its broad applicability. Minimizing and equalizing ionic potentials across both sublattices enhances conductivity by reducing the strength of anion-lithium interactions. Our analysis of local environments coordinating Li jumps reveals that balancing high and low-energy pathways is crucial for enabling macroscopic diffusion, supported by investigating percolating pathways. This study highlights the significance of the anionic framework in lithium mobility and informs the design of solid electrolytes for improved energy storage systems.

We have developed an innovative recyclable printed magnetoresistive sensor using GMR microflakes and AMR microparticles as functional fillers, with PECH as the elastomer binder. Under saturation magnetic fields of 100 mT and 30 mT, these sensors respectively exhibit magnetoresistance values of 4.7% and 0.45%. The excellent mechanical properties and thermal stability of the PECH elastomer binder endow these sensors with outstanding flexibility and temperature stability. This flexibility, low cost, and scalability make these sensors highly suitable for integration into flexible electronic devices, such as smart security systems and home automation. Moreover, these sensors are fully recyclable and reusable, allowing the materials to be separated, reused, and remanufactured without loss of performance. The low energy consumption of the production process and the recyclability of the materials significantly reduce the environmental impact of these magnetic field sensors.

This work reports the thermal and electron beam stabilities of a series of isostructural metal-organic frameworks (MOFs) of type MFM-300(M) (M = Al, Ga, In, Cr). MFM-300(Cr) was most stable under the electron beam, having an unusually high critical electron fluence of 1111 e Å while the Group 13 element MOFs were found to be less stable. Within Group 13, MFM-300(Al) had the highest critical electron fluence of 330 e Å, compared to 189 e Å and 147 e Å for the Ga and In MOFs, respectively. For all four MOFs, electron beam-induced structural degradation was independent of crystal size and was highly anisotropic, although both the length and width of the channels decreased during electron beam irradiation. Notably, MFM-300(Cr) was found to retain crystallinity while shrinking up to 10%. Thermal stability was studied using synchrotron X-ray diffraction at elevated temperature, which revealed critical temperatures for crystal degradation to be 605, 570, 490 and 480 °C for Al, Cr, Ga, and In, respectively. The pore channel diameters contracted by ≈0.5% on desorption of solvent species, but thermal degradation at higher temperatures was isotropic. The observed electron stabilities were found to scale with the relative inertness of the cations and correlate well to the measured lifetime of the materials when used as photocatalysts.

Photocatalyst systems combining donor polymers with acceptor molecules have shown the highest evolution rates for sacrificial hydrogen production from water for organic systems to date. Here, new donor molecules have been designed and synthesised taking inspiration from the structure-performance relationships which have been established in the development of non-fullerene acceptors. While a conventional bulk heterojunction (BHJ) pairing consists of a donor polymer and acceptor small molecule, here we have successfully reversed this approach by using new p-type small molecules in combination with a n-type conjugated polymer to produce non-conventional BHJ (ncBHJ) nanoparticles. We have applied these ncBHJs as photocatalysts in the sacrificial hydrogen evolution from water, and the best performing heterojunction displayed high activity for sacrificial hydrogen production from water with a hydrogen evolution rate of 22 321 μmol h g which compares well with the state-of-the-art for conventional BHJ photocatalyst systems.

The oxygen evolution reaction (OER) is a key reaction in the production of green hydrogen by water electrolysis. In alkaline media, the current state of the art catalysts used for the OER are based on non-noble metal oxides. However, despite their huge potential as OER catalysts, these materials exhibit various disadvantages including lack of stability and conductivity that hinder the wide-spread utilization of these materials in alkaline electrolyzer devices. This study highlights the innovative chemical functionalization of a mixed copper cobalt hydroxide with the VCT MXene to enhance the OER efficiency, addressing the need for effective electrocatalytic interfaces for sustainable hydrogen production. The herein synthesized CuCo@VCT electrocatalysts demonstrate remarkable activity, outperforming the pure CuCo catalysts for the OER and moreover show increased efficiency after 12 hours of continuous operation. This strategic integration improved the water oxidation performance of the pure oxide material by improving the composite's hydrophilicity, charge transfer properties and ability to hinder Cu leaching. The materials were characterized using an array of materials characterization techniques to help decipher both structure of the composite materials after synthesis and to elucidate the reasoning for the OER enhancement for the composites. This work demonstrates the significant potential of TMO-based nanomaterials combined with VCT for advanced innovative electrocatalytic interfaces in energy conversion applications.

Zinc metal batteries (ZMBs) are promising candidates for low-cost, intrinsically safe, and environmentally friendly energy storage systems. However, the anode is plagued with problems such as the parasitic hydrogen evolution reaction, surface passivation, corrosion, and a rough metal electrode morphology that is prone to short circuits. One strategy to overcome these issues is understanding surface processes to facilitate more homogeneous electrodeposition of zinc by guiding the alignment of electrodeposited zinc. Using Scanning Electrochemical Microscopy (SECM), the charge transport rate on zinc metal anodes was mapped, demonstrating that manipulating electrolyte concentration can influence zinc electrodeposition and solid electrolyte interphase (SEI) formation in ZMBs. Using XPS and Raman spectroscopy, it is demonstrated that an SEI is formed on zinc electrodes at neutral pH, composed primarily of a Zn(OH)SO·HO species, its formation being attributed to local pH increases at the interface. This work shows that more extended high-rate cycling can be achieved using a 1 M ZnSO electrolyte and that these systems have a reduced tendency for soft shorts. The improved cyclability in 1 M ZnSO was attributed to a more homogeneous and conductive interface formed, rather than the bulk electrolyte properties. This experimental methodology for studying metal battery electrodes is transferable to lithium metal and anode-free batteries, and other sustainable battery chemistries such as sodium, magnesium, and calcium.

Realization of ethane-trapping materials for separating ethane (CH) from ethylene (CH) by adsorption, to potentially replace the energy-intensive cryogenic distillation technology, is of prime importance in the petrochemical industry. It is still very challenging to target CH-selective adsorbents with both high CH capture capacity and gas selectivity. Herein, we report that a crystal engineering or reticular chemistry strategy enables the control of pore size and functionality in a family of isomorphic metal-organic frameworks (MOFs) for boosting the CH uptake and selectivity simultaneously. By altering the carboxylic acid linker in Ni(bdc)(ted), we developed two novel isoreticular MOFs, Ni(ndc)(ted) and Ni(adc)(ted) (termed ZJU-120 and ZJU-121, respectively), in which the pore sizes and nonpolar aromatic rings can be finely engineered. We discover that activated ZJU-120a with the optimized pore size (4.4 Å) and aromatic rings exhibits both a very high CH uptake (96 cm g at 0.5 bar and 296 K) and CH/CH selectivity (2.74), outperforming most of the CH-selective MOFs reported. Computational studies indicate that the suitable pore size and more nonpolar aromatic rings on the pore surfaces of ZJU-120a mainly contribute to its exceptional CH uptake and selectivity. The breakthrough experiments demonstrate that ZJU-120a can efficiently separate CH from 50/50 and 10/90CH/CH mixtures under ambient conditions.

Multi-element alloys and high-entropy alloys show promising electrocatalytic behavior for water splitting and other catalytic reactions, due to their highly tunable composition. While preparation and synthesis of these materials are thoroughly investigated, the true reactive surface composition is still not well understood, as it may significantly differ from the bulk composition. Precise knowledge and understanding of resulting surface composition is crucial for effective control of the electrocatalytic performance. In this work, low energy ion scattering spectroscopy was applied to determine the surface oxide composition of a series of Ni-based multi-metallic alloys with Mn, Fe, Co, and Cr under alkaline, neutral and acidic conditions. The composition of the surface oxide was investigated with sub-nanometer depth resolution. In electrochemical tests, good catalytic activity was found for the oxygen evolution reaction, although a strong dependence on the selected reaction conditions was observed. The surface composition under OER conditions deviates significantly from the bulk composition. No significant benefit of high entropy alloying compared with binary or ternary alloys concerning catalytic OER performance was found.