Efficient tandem electroreduction of nitrate into ammonia through coupling Cu single atoms with adjacent Co3O4

The nitrate (NO3-) electroreduction into ammonia (NH3) represents a promising approach for sustainable NH3 synthesis. However, the variation of adsorption configurations renders great difficulties in the simultaneous optimization of binding energy for the intermediates. Though the extensively reported Cu-based electrocatalysts benefit NO3- adsorption, one of the key issues lies in the accumulation of nitrite (NO2-) due to its weak adsorption, resulting in the rapid deactivation of catalysts and sluggish kinetics of subsequent hydrogenation steps. Here we report a tandem electrocatalyst by combining Cu single atoms catalysts with adjacent Co3O4 nanosheets to boost the electroreduction of NO3- to NH3. The obtained tandem catalyst exhibits a yield rate for NH3 of 114.0 mgNH 3 h-1 cm-2, which exceeds the previous values for the reported Cu-based catalysts. Mechanism investigations unveil that the combination of Co3O4 regulates the adsorption configuration of NO2- and strengthens the binding with NO2-, thus accelerating the electroreduction of NO3- to NH3.

Sub-millisecond lithiothermal synthesis of graphitic meso-microporous carbon

Porous carbons with concurrently high specific surface area and electronic conductivity are desirable by virtue of their desirable electron and ion transport ability, but conventional preparing methods suffer from either low yield or inferior quality carbons. Here we developed a lithiothermal approach to bottom-up synthesize highly meso-microporous graphitized carbon (MGC). The preparation can be finished in a few milliseconds by the self-propagating reaction between polytetrafluoroethylene powder and molten lithium (Li) metal, during which instant ultra-high temperature (>3000 K) was produced. This instantaneous carbon vaporization and condensation at ultra-high temperatures and in ultra-short duration enable the MGC to show a highly graphitized and continuously cross-coupled open pore structure. MGC displays superior electrochemical capacitor performance of exceptional power capability and ultralong-term cyclability. The processes used to make this carbon are readily scalable to industrial levels.

Multi-step FRET systems based on discrete supramolecular assemblies

Fluorescence resonance energy transfer (FRET) from the excited state of the donor to the ground state of the acceptor is one of the most important fluorescence mechanisms and has wide applications in light-harvesting systems, light-mediated therapy, bioimaging, optoelectronic devices, and information security fields. The phenomenon of sequential energy transfer in natural photosynthetic systems provides great inspiration for scientists to make full use of light energy. In recent years, discrete supramolecular assemblies (DSAs) have been successively constructed to incorporate donor and multiple acceptors, and to achieve multi-step FRET between them. This perspective describes recent advances in the fabrication and application of DSAs with multi-step FRET. These DSAs are categorized based on the non-covalent scaffolds, such as amphiphilic nanoparticles, host-guest assemblies, metal-coordination scaffolds, and biomolecular scaffolds. This perspective will also outline opportunities and future challenges in this research area.

Green moisture-electric generator based on supramolecular hydrogel with tens of milliamp electricity toward practical applications

Moisture-electric generators (MEGs) has emerged as promising green technology to achieve carbon neutrality in next-generation energy suppliers, especially combined with ecofriendly materials. Hitherto, challenges remain for MEGs as direct power source in practical applications due to low and intermittent electric output. Here we design a green MEG with high direct-current electricity by introducing polyvinyl alcohol-sodium alginate-based supramolecular hydrogel as active material. A single unit can generate an improved power density of ca. 0.11 mW cm-2, a milliamp-scale short-circuit current density of ca. 1.31 mA cm-2 and an open-circuit voltage of ca. 1.30 V. Such excellent electricity is mainly attributed to enhanced moisture absorption and remained water gradient to initiate ample ions transport within hydrogel by theoretical calculation and experiments. Notably, an enlarged current of ca. 65 mA is achieved by a parallel-integrated MEG bank. The scalable MEGs can directly power many commercial electronics in real-life scenarios, such as charging smart watch, illuminating a household bulb, driving a digital clock for one month. This work provides new insight into constructing green, high-performance and scalable energy source for Internet-of-Things and wearable applications.

Solvent-free selective hydrogenation of nitroaromatics to azoxy compounds over Co single atoms decorated on Nb2O5 nanomeshes

The solvent-free selective hydrogenation of nitroaromatics to azoxy compounds is highly important, yet challenging. Herein, we report an efficient strategy to construct individually dispersed Co atoms decorated on niobium pentaoxide nanomeshes with unique geometric and electronic properties. The use of this supported Co single atom catalysts in the selective hydrogenation of nitrobenzene to azoxybenzene results in high catalytic activity and selectivity, with 99% selectivity and 99% conversion within 0.5 h. Remarkably, it delivers an exceptionally high turnover frequency of 40377 h-1, which is amongst similar state-of-the-art catalysts. In addition, it demonstrates remarkable recyclability, reaction scalability, and wide substrate scope. Density functional theory calculations reveal that the catalytic activity and selectivity are significantly promoted by the unique electronic properties and strong electronic metal-support interaction in Co1/Nb2O5. The absence of precious metals, toxic solvents, and reagents makes this catalyst more appealing for synthesizing azoxy compounds from nitroaromatics. Our findings suggest the great potential of this strategy to access single atom catalysts with boosted activity and selectivity, thus offering blueprints for the design of nanomaterials for organocatalysis.

Thermally stable Ni foam-supported inverse CeAlOx/Ni ensemble as an active structured catalyst for CO2 hydrogenation to methane

Nickel is the most widely used inexpensive active metal center of the heterogeneous catalysts for CO2 hydrogenation to methane. However, Ni-based catalysts suffer from severe deactivation in CO2 methanation reaction due to the irreversible sintering and coke deposition caused by the inevitable localized hotspots generated during the vigorously exothermic reaction. Herein, we demonstrate the inverse CeAlOx/Ni composite constructed on the Ni-foam structure support realizes remarkable CO2 methanation catalytic activity and stability in a wide operation temperature range from 240 to 600 °C. Significantly, CeAlOx/Ni/Ni-foam catalyst maintains its initial activity after seven drastic heating-cooling cycles from RT to 240 to 600 °C. Meanwhile, the structure catalyst also shows water resistance and long-term stability under reaction condition. The promising thermal stability and water-resistance of CeAlOx/Ni/Ni-foam originate from the excellent heat and mass transport efficiency which eliminates local hotspots and the formation of Ni-foam stabilized CeAlOx/Ni inverse composites which effectively anchored the active species and prevents carbon deposition from CH4 decomposition.

Electron paramagnetic resonance as a tool to determine the sodium charge storage mechanism of hard carbon

Hard carbon is a promising negative electrode material for rechargeable sodium-ion batteries due to the ready availability of their precursors and high reversible charge storage. The reaction mechanisms that drive the sodiation properties in hard carbons and subsequent electrochemical performance are strictly linked to the characteristic slope and plateau regions observed in the voltage profile of these materials. This work shows that electron paramagnetic resonance (EPR) spectroscopy is a powerful and fast diagnostic tool to predict the extent of the charge stored in the slope and plateau regions during galvanostatic tests in hard carbon materials. EPR lineshape simulation and temperature-dependent measurements help to separate the nature of the spins in mechanochemically modified hard carbon materials synthesised at different temperatures. This proves relationships between structure modification and electrochemical signatures in the galvanostatic curves to obtain information on their sodium storage mechanism. Furthermore, through ex situ EPR studies we study the evolution of these EPR signals at different states of charge to further elucidate the storage mechanisms in these carbons. Finally, we discuss the interrelationship between EPR spectroscopy data of the hard carbon samples studied and their corresponding charging storage mechanism.

Water-assisted oxidative redispersion of Cu particles through formation of Cu hydroxide at room temperature

Sintering of active metal species often happens during catalytic reactions, which requires redispersion in a reactive atmosphere at elevated temperatures to recover the activity. Herein, we report a simple method to redisperse sintered Cu catalysts via O2-H2O treatment at room temperature. In-situ spectroscopic characterizations reveal that H2O induces the formation of hydroxylated Cu species in humid O2, pushing surface diffusion of Cu atoms at room temperature. Further, surface OH groups formed on most hydroxylable support surfaces such as γ-Al2O3, SiO2, and CeO2 in the humid atmosphere help to pull the mobile Cu species and enhance Cu redispersion. Both pushing and pulling effects of gaseous H2O promote the structural transformation of Cu aggregates into highly dispersed Cu species at room temperature, which exhibit enhanced activity in reverse water gas shift and preferential oxidation of carbon monoxide reactions. These findings highlight the important role of H2O in the dynamic structure evolution of supported metal nanocatalysts and lay the foundation for the regeneration of sintered catalysts under mild conditions.

A silicon photoanode protected with TiO2/stainless steel bilayer stack for solar seawater splitting

Photoelectrochemical seawater splitting is a promising route for direct utilization of solar energy and abundant seawater resources for H2 production. However, the complex salinity composition in seawater results in intractable challenges for photoelectrodes. This paper describes the fabrication of a bilayer stack consisting of stainless steel and TiO2 as a cocatalyst and protective layer for Si photoanode. The chromium-incorporated NiFe (oxy)hydroxide converted from stainless steel film serves as a protective cocatalyst for efficient oxygen evolution and retarding the adsorption of corrosive ions from seawater, while the TiO2 is capable of avoiding the plasma damage of the surface layer of Si photoanode during the sputtering of stainless steel catalysts. By implementing this approach, the TiO2 layer effectively shields the vulnerable semiconductor photoelectrode from the harsh plasma sputtering conditions in stainless steel coating, preventing surface damages. Finally, the Si photoanode with the bilayer stack inhibits the adsorption of chloride and realizes 167 h stability in chloride-containing alkaline electrolytes. Furthermore, this photoanode also demonstrates stable performance under alkaline natural seawater for over 50 h with an applied bias photon-to-current efficiency of 2.62%.

Isotope engineering achieved by local coordination design in Ti-Pd co-doped ZrCo-based alloys

Deuterium/Tritium (D/T) handling in defined proportions are pivotal to maintain steady-state operation for fusion reactors. However, the hydrogen isotope effect in metal-hydrogen systems always disturbs precise D/T ratio control. Here, we reveal the dominance of kinetic isotope effect during desorption. To reconcile the thermodynamic stability and isotope effect, we demonstrate a quantitative indicator of Tgap and further a local coordination design strategy that comprises thermodynamic destabilization with vibration enhancement of interstitial isotopes for isotope engineering. Based on theoretical screening analysis, an optimized Ti-Pd co-doped Zr0.8Ti0.2Co0.8Pd0.2 alloy is designed and prepared. Compared to ZrCo alloy, the optimal alloy enables consistent isotope delivery together with a three-fold lower Tgap, a five-fold lower energy barrier difference, a one-third lower isotopic composition deviation during desorption and an over two-fold higher cycling capacity. This work provides insights into the interaction between alloy and hydrogen isotopes, thus opening up feasible approaches to support high-performance fusion reactors.

Enhancement of electrocatalysis through magnetic field effects on mass transport

Magnetic field effects on electrocatalysis have recently gained attention due to the substantial enhancement of the oxygen evolution reaction (OER) on ferromagnetic catalysts. When detecting an enhanced catalytic activity, the effect of magnetic fields on mass transport must be assessed. In this study, we employ a specifically designed magneto-electrochemical system and non-magnetic electrodes to quantify magnetic field effects. Our findings reveal a marginal enhancement in reactions with high reactant availability, such as the OER, whereas substantial boosts exceeding 50% are observed in diffusion limited reactions, exemplified by the oxygen reduction reaction (ORR). Direct visualization and quantification of the whirling motion of ions under a magnetic field underscore the importance of Lorentz forces acting on the electrolyte ions, and demonstrate that bubbles' movement is a secondary phenomenon. Our results advance the fundamental understanding of magnetic fields in electrocatalysis and unveil new prospects for developing more efficient and sustainable energy conversion technologies.

Phenol as proton shuttle and buffer for lithium-mediated ammonia electrosynthesis

Ammonia is a crucial component in the production of fertilizers and various nitrogen-based compounds. Now, the lithium-mediated nitrogen reduction reaction (Li-NRR) has emerged as a promising approach for ammonia synthesis at ambient conditions. The proton shuttle plays a critical role in the proton transfer process during Li-NRR. However, the structure-activity relationship and design principles for effective proton shuttles have not yet been established in practical Li-NRR systems. Here, we propose a general procedure for verifying a true proton shuttle and established design principles for effective proton shuttles. We systematically evaluate several classes of proton shuttles in a continuous-flow reactor with hydrogen oxidation at the anode. Among the tested proton shuttles, phenol exhibits the highest Faradaic efficiency of 72 ± 3% towards ammonia, surpassing that of ethanol, which has been commonly used so far. Experimental investigations including operando isotope-labelled mass spectrometry proved the proton-shuttling capability of phenol. Further mass transport modeling sheds light on the mechanism.

Capturing ion trapping and detrapping dynamics in electrochromic thin films

Ion trapping has been found to be responsible for the performance degradation in electrochromic oxide thin films, and a detrapping procedure was proved to be effective to rejuvenate the degraded films. Despite of the studies on ion trapping and detrapping, its dynamics remain largely unknown. Moreover, coloration mechanisms of electrochromic oxides are also far from clear, limiting the development of superior devices. Here, we visualize ion trapping and detrapping dynamics in a model electrochromic material, amorphous WO3. Specifically, formation of orthorhombic Li2WO4 during long-term cycling accounts for the origin of shallow traps. Deep traps are multiple-step-determined, composed of mixed W4+-Li2WO4, amorphous Li2WO4 and W4+-Li2O. The non-decomposable W4+-Li2WO4 couple is the origin of the irreversible traps. Furthermore, we demonstrate that, besides the typical small polaron hopping between W5+ ↔ W6+ sites, bipolaron hopping between W4+ ↔ W6+ sites gives rise to optical absorption in the short-wavelength region. Overall, we provide a general picture of electrochromism based on polaron hopping. Ion trapping and detrapping were demonstrated to also prevail in other cathodic electrochromic oxides. This work not only provides the ion trapping and detrapping dynamics of WO3, but also open avenues to study other cathodic electrochromic oxides and develop superior electrochromic devices with great durability.

Supra-biological performance of immobilized enzymes enabled by chaperone-like specific non-covalent interactions

Designing complex synthetic materials for enzyme immobilization could unlock the utility of biocatalysis in extreme environments. Inspired by biology, we investigate the use of random copolymer brushes as dynamic immobilization supports that enable supra-biological catalytic performance of immobilized enzymes. This is demonstrated by immobilizing Bacillus subtilis Lipase A on brushes doped with aromatic moieties, which can interact with the lipase through multiple non-covalent interactions. Incorporation of aromatic groups leads to a 50 °C increase in the optimal temperature of lipase, as well as a 50-fold enhancement in enzyme activity. Single-molecule FRET studies reveal that these supports act as biomimetic chaperones by promoting enzyme refolding and stabilizing the enzyme's folded and catalytically active state. This effect is diminished when aromatic residues are mutated out, suggesting the importance of π-stacking and π-cation interactions for stabilization. Our results underscore how unexplored enzyme-support interactions may enable uncharted opportunities for using enzymes in industrial biotransformations.

Battery deactivation with redox shuttles for safe and efficient recycling

To safely recycle spent lithium-ion batteries (LIBs), their deactivation as a pretreatment is essential. However, the conventional deactivation methods, mainly inducing an external short circuit, cannot be applied to LIBs with disconnected electrical circuits or Li deposited, despite their safety risk. Here, we propose a deactivation method using redox shuttles (RSs). The addition of an RS with redox potentials located between the two electrode potentials into a LIB electrochemically induces an internal short circuit with or without disconnected electrical circuits. A fully charged LIB discharges to approximately 0 V when a deactivation agent containing ferrocene or phenothiazine as an RS is added. Moreover, we demonstrate that RSs introduced into LIB can simultaneously dissolve Li deposited on the negative electrode surface and return it to the positive electrode as mobile ions. These characteristics of our method contribute to the improvement in safety and collection rate of Li in the recycling processes, promoting the sustainability of LIBs.

Decoupled oxidation process enabled by atomically dispersed copper electrodes for in-situ chemical water treatment

In-situ wastewater treatment has gained popularity due to cost and energy savings tailored to water sources and user needs. However, this treatment, particularly through advanced oxidation processes (AOPs), poses ecological risks due to the need for strong oxidizing agents. Here, we present a decoupled oxidation process (DOP) using single-atom copper-modified graphite felt electrodes. This process creates a positive potential difference (ΔE ~ 0.5 V) between spatially isolated oxidants and organics and drives electron transfer-based redox reactions. The approach avoids the drawbacks of conventional AOPs, while being capable of treating various recalcitrant electron-rich organics. A floating water treatment device designed based on the DOP approach can degrade organic molecules in large bodies of water with oxidants stored separately in the device. We demonstrate that over 200 L of contaminated water can be treated with a floating device containing only 40 mL of oxidant (10 mM peroxysulphate). The modular device can be used in tandem structures on demand, maximizing water remediation per unit area. Our result provides a promising, eco-friendly method for in-situ water treatment that is unattainable with existing techniques.

Automatically Generated Datasets: Present and Potential Self-Cleaning Coating Materials

The rise of urbanization coupled with pollution has highlighted the importance of outdoor self-cleaning coatings. These revolutionary coatings contribute to the longevity of various surfaces and reduce maintenance costs for a wide range of applications. Despite ongoing research to develop efficient and durable self-cleaning coatings, adopting systematic research methodologies could accelerate these advancements. In this work, we use Natural Language Processing (NLP) strategies to generate open- and traceable-sourced datasets about self-cleaning coating materials from 39,011 multi-disciplinary papers. The data are from function-based and property-based corpora for self-cleaning purposes. These datasets are presented in four different formats for diverse uses or combined uses: material frequency statistics, material dictionary, measurement value datasets for self-cleaning-related properties and optical properties, and sentiment statistics of material stability and durability. This provides a literature-based data resource for the development of self-cleaning coatings and also offers potential pathways for material discovery and prediction by machine learning.

Atomically synergistic Zn-Cr catalyst for iso-stoichiometric co-conversion of ethane and CO2 to ethylene and CO

Developing atomically synergistic bifunctional catalysts relies on the creation of colocalized active atoms to facilitate distinct elementary steps in catalytic cycles. Herein, we show that the atomically-synergistic binuclear-site catalyst (ABC) consisting of [Formula: see text]-O-Cr6+ on zeolite SSZ-13 displays unique catalytic properties for iso-stoichiometric co-conversion of ethane and CO2. Ethylene selectivity and utilization of converted CO2 can reach 100 % and 99.0% under 500  °C at ethane conversion of 9.6%, respectively. In-situ/ex-situ spectroscopic studies and DFT calculations reveal atomic synergies between acidic Zn and redox Cr sites. [Formula: see text] ([Formula: see text]) sites facilitate β-C-H bond cleavage in ethane and the formation of Zn-Hδ- hydride, thereby the enhanced basicity promotes CO2 adsorption/activation and prevents ethane C-C bond scission. The redox Cr site accelerates CO2 dissociation by replenishing lattice oxygen and facilitates H2O formation/desorption. This study presents the advantages of the ABC concept, paving the way for the rational design of novel advanced catalysts.

Efficient conversion of propane in a microchannel reactor at ambient conditions

The oxidative dehydrogenation of propane, primarily sourced from shale gas, holds promise in meeting the surging global demand for propylene. However, this process necessitates high operating temperatures, which amplifies safety concerns in its application due to the use of mixed propane and oxygen. Moreover, these elevated temperatures may heighten the risk of overoxidation, leading to carbon dioxide formation. Here we introduce a microchannel reaction system designed for the oxidative dehydrogenation of propane within an aqueous environment, enabling highly selective and active propylene production at room temperature and ambient pressure with mitigated safety risks. A propylene selectivity of over 92% and production rate of 19.57 mmol mCu-2 h-1 are simultaneously achieved. This exceptional performance stems from the in situ creation of a highly active, oxygen-containing Cu catalytic surface for propane activation, and the enhanced propane transfer via an enlarged gas-liquid interfacial area and a reduced diffusion path by establishing a gas-liquid Taylor flow using a custom-made T-junction microdevice. This microchannel reaction system offers an appealing approach to accelerate gas-liquid-solid reactions limited by the solubility of gaseous reactant.

High-performance p-type V2O3 films by spray pyrolysis for transparent conducting oxide applications

High-quality epitaxial p-type V2O3 thin films have been synthesized by spray pyrolysis. The films exhibited excellent electrical performance, with measurable mobility and high carrier concentration. The conductivity of the films varied between 115 and 1079 Scm-1 while the optical transparency of the films ranged from 32 to 65% in the visible region. The observed limitations in thinner films' mobility were attributed to the nanosized granular structure and the presence of two preferred growth orientations. The 60 nm thick V2O3 film demonstrated a highly competitive transparency-conductivity figure of merit compared to the state-of-the-art.

Unlocking osmotic energy harvesting potential in challenging real-world hypersaline environments through vermiculite-based hetero-nanochannels

Nanochannel membranes have demonstrated remarkable potential for osmotic energy harvesting; however, their efficiency in practical high-salinity systems is hindered by reduced ion selectivity. Here, we propose a dual-separation transport strategy by constructing a two-dimensional (2D) vermiculite (VMT)-based heterogeneous nanofluidic system via an eco-friendly and scalable method. The cations are initially separated and enriched in micropores of substrates during the transmembrane diffusion, followed by secondary precise sieving in ultra-thin VMT laminates with high ion flux. Resultantly, our nanofluidic system demonstrates efficient osmotic energy harvesting performance, especially in hypersaline environment. Notably, we achieve a maximum power density of 33.76 W m-2, a 6.2-fold improvement with a ten-fold increase in salinity gradient, surpassing state-of-the-art nanochannel membranes under challenging conditions. Additionally, we confirm practical hypersaline osmotic power generation using various natural salt-lake brines, achieving a power density of 25.9 W m-2. This work triggers the hopes for practical blue energy conversion using advanced nanoarchitecture.

2-Dimensional Ti3C2Tx/NaF nano-composites as electrode materials for hybrid battery-supercapacitor applications

The increasing global demand for energy storage solutions has spurred interest in advanced materials for electrochemical energy storage devices. Transition-metal carbides and nitrides, known as MXenes, are characterized by remarkable conductivity and tunable properties, They have gained significant attention for their potential in energy storage applications. The properties of two-dimensional (2-D) MXenes can be tuned by doping or composite formation. We report a novel Ti3C2Tx/NaF composite prepared via a straightforward hydrothermal process for supercapacitor electrode applications. Three composites with varying NaF concentrations (1%, 3%, and 5%) were synthesized under similar conditions. Structural characterization using X-ray diffraction (XRD) and scanning electron microscopy confirmed the successful formation of the composites, whereas distinct shifts in XRD peaks and new peaks revealed the presence of NaF. Electrochemical performance was evaluated by cyclic voltammetry, galvanostatic charging-discharging, and electrochemical impedance spectroscopy. The composites exhibited pseudo-capacitive behavior with reversible redox reactions during charge and discharge cycles. Specific capacitance of 191 F/g at scan rates of 2 mV/s was measured in 1 M KOH. Electrochemical impedance spectroscopy revealed an escalating impedance factor as NaF content increases within Ti3C2Tx. This study underscores the versatile energy storage potential of Ti3C2Tx/NaF composites, offering insights into their tailored properties and behavior.

Graphene nanowalls formation investigated by Electron Energy Loss Spectroscopy

The properties of layered materials are significantly dependent on their lattice orientations. Thus, the growth of graphene nanowalls (GNWs) on Cu through PECVD has been increasingly studied, yet the underlying mechanisms remain unclear. In this study, we examined the GNWs/Cu interface and investigated the evolution of their microstructure using advanced Scanning transmission electron microscopy and Electron Energy Loss Spectroscopy (STEM-EELS). GNWs interface and initial root layers of comprise graphitic carbon with horizontal basal graphene (BG) planes that conform well to the catalyst surface. In the vertical section, the walls show a mix of graphitic and turbostratic carbon, while the latter becomes more noticeable close to the top edges of the GMWs film. Importantly, we identified growth process began with catalysis at Cu interface forming BG, followed by defect induction and bending at 'coalescence points' of neighboring BG, which act as nucleation sites for vertical growth. We reported that although classical thermal CVD mechanism initially dominates, growth of graphene later deviates a few nanometers from the interface to form GNWs. Nascent walls are no longer subjected to the catalytic action of Cu, and their development is dominated by the stitching of charged carbon species originating in the plasma with basal plane edges.

Regulating Au coverage for the direct oxidation of methane to methanol

The direct oxidation of methane to methanol under mild conditions is challenging owing to its inadequate activity and low selectivity. A key objective is improving the selective oxidation of the first carbon-hydrogen bond of methane, while inhibiting the oxidation of the remaining carbon-hydrogen bonds to ensure high yield and selectivity of methanol. Here we design ultrathin PdxAuy nanosheets and revealed a volcano-type relationship between the binding strength of hydroxyl radical on the catalyst surface and catalytic performance using experimental and density functional theory results. Our investigations indicate a trade-off relationship between the reaction-triggering and reaction-conversion steps in the reaction process. The optimized Pd3Au1 nanosheets exhibits a methanol production rate of 147.8 millimoles per gram of Pd per hour, with a selectivity of 98% at 70 °C, representing one of the most efficient catalysts for the direct oxidation of methane to methanol.

CO2 hydrogenation over Fe-Co bimetallic catalysts with tunable selectivity through a graphene fencing approach

Tuning CO2 hydrogenation product distribution to obtain high-selectivity target products is of great significance. However, due to the imprecise regulation of chain propagation and hydrogenation reactions, the oriented synthesis of a single product is challenging. Herein, we report an approach to controlling multiple sites with graphene fence engineering that enables direct conversion of CO2/H2 mixtures into different types of hydrocarbons. Fe-Co active sites on the graphene fence surface present 50.1% light olefin selectivity, while the spatial Fe-Co nanoparticles separated by graphene fences achieve liquefied petroleum gas of 43.6%. With the assistance of graphene fences, iron carbides and metallic cobalt can efficiently regulate C-C coupling and olefin secondary hydrogenation reactions to achieve product-selective switching between light olefins and liquefied petroleum gas. Furthermore, it also creates a precedent for CO2 direct hydrogenation to liquefied petroleum gas via a Fischer-Tropsch pathway with the highest space-time yields compared to other reported composite catalysts.

Synthesis of core@shell catalysts guided by Tammann temperature

Designing high-performance thermal catalysts with stable catalytic sites is an important challenge. Conventional wisdom holds that strong metal-support interactions can benefit the catalyst performance, but there is a knowledge gap in generalizing this effect across different metals. Here, we have successfully developed a generalizable strong metal-support interaction strategy guided by Tammann temperatures of materials, enabling functional oxide encapsulation of transition metal nanocatalysts. As an illustrative example, Co@BaAl2O4 core@shell is synthesized and tracked in real-time through in-situ microscopy and spectroscopy, revealing an unconventional strong metal-support interaction encapsulation mechanism. Notably, Co@BaAl2O4 exhibits exceptional activity relative to previously reported core@shell catalysts, displaying excellent long-term stability during high-temperature chemical reactions and overcoming the durability and reusability limitations of conventional supported catalysts. This pioneering design and widely applicable approach has been validated to guide the encapsulation of various transition metal nanoparticles for environmental tolerance functionalities, offering great potential to advance energy, catalysis, and environmental fields.

Structural regulation of halide superionic conductors for all-solid-state lithium batteries

Metal halide solid-state electrolytes have gained widespread attention due to their high ionic conductivities, wide electrochemical stability windows, and good compatibility with oxide cathode materials. The exploration of highly ionic conductive halide electrolytes is actively ongoing. Thus, understanding the relationship between composition and crystal structure can be a critical guide for designing better halide electrolytes, which still remains obscure for reliable prediction. Here we show that the cationic polarization factor, which describes the geometric and ionic conditions, is effective in predicting the stacking structure of halide electrolytes formation. By supplementing this principle with rational design and preparation of more than 10 lithium halide electrolytes with high conductivity over 10-3 S cm-1 at 25 °C, we establish that there should be a variety of promising halide electrolytes that have yet to be discovered and developed. This methodology may enable the systematic screening of various potential halide electrolytes and demonstrate an approach to the design of halide electrolytes with superionic conductivity beyond the structure and stability predictions.

Universal machine learning aided synthesis approach of two-dimensional perovskites in a typical laboratory

The past decade has witnessed the significant efforts in novel material discovery in the use of data-driven techniques, in particular, machine learning (ML). However, since it needs to consider the precursors, experimental conditions, and availability of reactants, material synthesis is generally much more complex than property and structure prediction, and very few computational predictions are experimentally realized. To solve these challenges, a universal framework that integrates high-throughput experiments, a priori knowledge of chemistry, and ML techniques such as subgroup discovery and support vector machine is proposed to guide the experimental synthesis of materials, which is capable of disclosing structure-property relationship hidden in high-throughput experiments and rapidly screening out materials with high synthesis feasibility from vast chemical space. Through application of our approach to challenging and consequential synthesis problem of 2D silver/bismuth organic-inorganic hybrid perovskites, we have increased the success rate of the synthesis feasibility by a factor of four relative to traditional approaches. This study provides a practical route for solving multidimensional chemical acceleration problems with small dataset from typical laboratory with limited experimental resources available.

Spin polarized Fe1-Ti pairs for highly efficient electroreduction nitrate to ammonia

Electrochemical nitrate reduction to ammonia offers an attractive solution to environmental sustainability and clean energy production but suffers from the sluggish *NO hydrogenation with the spin-state transitions. Herein, we report that the manipulation of oxygen vacancies can contrive spin-polarized Fe1-Ti pairs on monolithic titanium electrode that exhibits an attractive NH3 yield rate of 272,000 μg h-1 mgFe-1 and a high NH3 Faradic efficiency of 95.2% at -0.4 V vs. RHE, far superior to the counterpart with spin-depressed Fe1-Ti pairs (51000 μg h-1 mgFe-1) and the mostly reported electrocatalysts. The unpaired spin electrons of Fe and Ti atoms can effectively interact with the key intermediates, facilitating the *NO hydrogenation. Coupling a flow-through electrolyzer with a membrane-based NH3 recovery unit, the simultaneous nitrate reduction and NH3 recovery was realized. This work offers a pioneering strategy for manipulating spin polarization of electrocatalysts within pair sites for nitrate wastewater treatment.

Giant adiabatic temperature change and its direct measurement of a barocaloric effect in a charge-transfer solid

Solid refrigerants exhibiting a caloric effect upon applying external stimuli are receiving attention as one of the next-generation refrigeration technologies. Herein, we report a new inorganic refrigerant, rubidium cyano-bridged manganese-iron-cobalt ternary metal assembly (cyano-RbMnFeCo). Cyano-RbMnFeCo shows a reversible barocaloric effect with large reversible adiabatic temperature changes of 74 K (from 57 °C to -17 °C) at 340 MPa, and 85 K (from 88 °C to 3 °C) at 560 MPa. Such large reversible adiabatic temperature changes have yet to be reported among caloric effects in solid-solid phase transition refrigerants. The reversible refrigerant capacity is 26000 J kg-1 and the temperature window is 142 K. Additionally, cyano-RbMnFeCo shows barocaloric effects even at low pressures, e.g., reversible adiabatic temperature change is 21 K at 90 MPa. Furthermore, direct measurement of the temperature change using a thermocouple shows +44 K by applying pressure. The temperature increase and decrease upon pressure application and release are repeated over 100 cycles without any degradation of the performance. This material series also possesses a high thermal conductivity value of 20.4 W m-1 K-1. The present barocaloric material may realize a high-efficiency solid refrigerant.

Machine learning and atomistic origin of high dielectric permittivity in oxides

Discovering new stable materials with large dielectric permittivity is important for future energy storage and electronics applications. Theoretical and computational approaches help design new materials by elucidating microscopic mechanisms and establishing structure-property relations. Ab initio methods can be used to reliably predict the dielectric response, but for fast materials screening, machine learning (ML) approaches, which can directly infer properties from the structural information, are needed. Here, random forest and graph convolutional neural network models are trained and tested to predict the dielectric constant from the structural information. We create a database of the dielectric properties of oxides and design, train, and test the two ML models. Both approaches show similar performance and can successfully predict response based on the structure. The analysis of the feature importance allows identification of local geometric features leading to the high dielectric permittivity of the crystal. Dimensionality reduction and clustering further confirms the relevance of descriptors and compositional features for obtaining high dielectric permittivity.

Elucidating the structure-stability relationship of Cu single-atom catalysts using operando surface-enhanced infrared absorption spectroscopy

Understanding the structure-stability relationship of catalysts is imperative for the development of high-performance electrocatalytic devices. Herein, we utilize operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) to quantitatively monitor the evolution of Cu single-atom catalysts (SACs) during the electrochemical reduction of CO2 (CO2RR). Cu SACs are converted into 2-nm Cu nanoparticles through a reconstruction process during CO2RR. The evolution rate of Cu SACs is highly dependent on the substrates of the catalysts due to the coordination difference. Density functional theory calculations demonstrate that the stability of Cu SACs is highly dependent on their formation energy, which can be manipulated by controlling the affinity between Cu sites and substrates. This work highlights the use of operando ATR-SEIRAS to achieve mechanistic understanding of structure-stability relationship for long-term applications.

Spectroscopic ellipsometry modelling of Cr+ implanted copper oxide thin films

In this paper, we present modelling of spectroscopic ellipsometry data. The measured samples are thin films of copper oxides modified with the ion implantation method. The samples were prepared using reactive magnetron sputtering. Thin films of CuO and Cu4O3 were deposited and subjected to Cr ion implantation with an energy of 15 keV and a dose of 5 × 1016 ions/cm2. The decrease in crystallinity of the thin film as a result of the implantation was inspected with X-ray diffraction measurements. The implantation of Cr+ ions was simulated using the Stopping and Range of Ions in Matter software by Ziegler and Biersack. Ion beam energy of 15 keV was simulated to estimate the distribution of Cr ions in the copper oxides thin films. Optical parameters, such as refractive index, extinction coefficient, and absorption coefficient of the thin films, were investigated with spectroscopic ellipsometry. Multilayered models based on Tauc-Lorentz oscillators were developed for both oxides. Analysis of the optical properties showed that the ion implantation with Cr decreased the absorption of copper oxides thin films and the modelling proved that the material properties of top layers changed the most.

Language models and protocol standardization guidelines for accelerating synthesis planning in heterogeneous catalysis

Synthesis protocol exploration is paramount in catalyst discovery, yet keeping pace with rapid literature advances is increasingly time intensive. Automated synthesis protocol analysis is attractive for swiftly identifying opportunities and informing predictive models, however such applications in heterogeneous catalysis remain limited. In this proof-of-concept, we introduce a transformer model for this task, exemplified using single-atom heterogeneous catalysts (SACs), a rapidly expanding catalyst family. Our model adeptly converts SAC protocols into action sequences, and we use this output to facilitate statistical inference of their synthesis trends and applications, potentially expediting literature review and analysis. We demonstrate the model's adaptability across distinct heterogeneous catalyst families, underscoring its versatility. Finally, our study highlights a critical issue: the lack of standardization in reporting protocols hampers machine-reading capabilities. Embracing digital advances in catalysis demands a shift in data reporting norms, and to this end, we offer guidelines for writing protocols, significantly improving machine-readability. We release our model as an open-source web application, inviting a fresh approach to accelerate heterogeneous catalysis synthesis planning.

Simulation of thermal hazards risk in octogen based on non-isothermal DSC data

To evaluate the possible thermal risks associated with the storage of octogen (HMX), non-isothermal differential scanning calorimetry (DSC) experiments were conducted in order to ascertain the kinetic model and parameters governing its thermal decomposition. DSC measurements indicate that HMX underwent a crystal transformation prior to thermal decomposition. A kinetic model for the autocatalytic thermal decomposition process was developed through the analysis of its primary exothermic peaks. Subsequently, numerical simulations were performed using the aforementioned kinetic model to assess the potential thermal explosion hazard of HMX under two distinct storage conditions. The comparison was made between the models of HMX autocatalytic decomposition temperature and thermal explosion critical temperature under two distinct storage conditions. The prediction of the influence of ambient temperature on the critical temperature of thermal explosion is conducted simultaneously. Finally, the thermal hazard parameters of HMX under different package quality are given.

Enhanced supercapacitor materials from pyrolyzed algae and graphene composites

This study focuses on the synthesis and characterization of supercapacitor materials derived from pyrolyzed natural compounds. Four compounds were investigated: methylcellulose with lysine (ML), methylcellulose with lysine-graphene composite (MLG), algae (A), and algae-graphene composite (AG). The pyrolysis process was utilized to convert these natural compounds into carbon-based materials suitable for supercapacitor applications. The properties of the resulting materials were analyzed extensively to evaluate their potential as supercapacitor electrodes. The electrochemical performance, including specific capacitance, cyclic stability, and rate capability was measured using various characterization techniques. The effects of incorporating graphene into the lysine-methylcellulose and algae matrices were also studied to explore the enhancements in supercapacitor performance. In both cases, the addition of graphene resulted in a positive effect. Among all the materials investigated, the algae-graphene composite exhibited the most favorable properties, demonstrating a specific capacitance of 192 F g-1 after 10,000 galvanostatic charge-discharge cycles at a current of 5 A g-1 in K2SO4 electrolyte. This exceptional performance underscores the potential of the algae-graphene composite as a highly efficient and durable electrode material for supercapacitor applications.

Ambipolar surface conduction in oxygen sub-stoichiometric molybdenum oxide films

The surface electric conduction in amorphous and crystallized molybdenum oxide films was studied as a function of electronic structure by current-voltage and simultaneous spectroscopic ellipsometry measurements on structures of the kind Al/Molybdenum oxide (MoOx)/Al, at temperatures up to 400 °C and in ambient air. At room temperature, both amorphous and crystalline MoOx samples were found to be sub-stoichiometric in oxygen. The random distribution of oxygen vacancies and the imperfect atomic ordering induced the creation of an intermediate band (IB) located near the valence band and of individual electronic gap states. At temperatures below 300 °C, the conduction was found to exhibit ambipolar character in which electrons and holes participated, the former moving in the conduction band and the latter in the IB and though gap states. Above 300 °C, due to samples gradual oxidation and improvement of atomic ordering (samples crystallization), the density of states in the IB and the gap gradually decreased. The above in their turn resulted in the gradual suppression of the ambipolar character of the conduction, which at 400 °C was completely suppressed and became similar to that of ordinary n-type semiconductor. The above phenomena were found to be reversible, so as the semiconducting MoOx samples were returning to room temperature the ambipolarity of the conduction was gradually re-appearing giving rise to an unusual phenomenon of "metallic" temperature variation of electrical resistance when electrons were injected.

Enhancing supercapacitor performance through design optimization of laser-induced graphene and MWCNT coatings for flexible and portable energy storage

The field of supercapacitors consistently focuses on research and challenges to improve energy efficiency, capacitance, flexibility, and stability. Low-cost laser-induced graphene (LIG) offers a promising alternative to commercially available graphene for next-generation wearable and portable devices, thanks to its remarkable specific surface area, excellent mechanical flexibility, and exceptional electrical properties. We report on the development of LIG-based flexible supercapacitors with optimized geometries, which demonstrate high capacitance and energy density while maintaining flexibility and stability. Three-dimensional porous graphene films were synthesized, and devices with optimized parameters were fabricated and tested. One type of device utilized LIG, while two other types were fabricated on LIG by coating multi-walled carbon nanotubes (MWCNT) at varying concentrations. Characterization techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy, and voltammetry, were employed to analyze the fabricated devices. AFM analysis revealed a surface roughness of 2.03 µm for LIG due to laser treatment. SEM images displayed compact, dense, and porous surface morphology. XRD analysis confirmed the presence of graphene and graphene oxide, which was further supported by energy-dispersive X-ray spectroscopy (EDX) data. Raman spectroscopy indicated that the fabricated samples exhibited distinct D and G bands at 1362 cm-1 and 1579 cm-1, respectively. Cyclic voltammetry (CV) results showed that LIG's capacitance, power density, and energy density were 6.09 mF cm-2, 0.199 mW cm-2, and 3.38 µWh cm-2, respectively, at a current density of 0.2 mA cm-2. The LIG-MWCNT coated electrode exhibited a higher energy density of 6.05 µWh cm-2 and an areal-specific capacitance of 51.975 mF cm-2 compared to the LIG-based devices. The fabricated device has potential applications in smart electronics, nanorobotics, microelectromechanical systems (MEMS), and wearable and portable electronics.

A polymer tethering strategy to achieve high metal loading on catalysts for Fenton reactions

The development of heterogenous catalysts based on the synthesis of 2D carbon-supported metal nanocatalysts with high metal loading and dispersion is important. However, such practices remain challenging to develop. Here, we report a self-polymerization confinement strategy to fabricate a series of ultrafine metal embedded N-doped carbon nanosheets (M@N-C) with loadings of up to 30 wt%. Systematic investigation confirms that abundant catechol groups for anchoring metal ions and entangled polymer networks with the stable coordinate environment are essential for realizing high-loading M@N-C catalysts. As a demonstration, Fe@N-C exhibits the dual high-efficiency performance in Fenton reaction with both impressive catalytic activity (0.818 min-1) and H2O2 utilization efficiency (84.1%) using sulfamethoxazole as the probe, which has not yet been achieved simultaneously. Theoretical calculations reveal that the abundant Fe nanocrystals increase the electron density of the N-doped carbon frameworks, thereby facilitating the continuous generation of long-lasting surface-bound •OH through lowering the energy barrier for H2O2 activation. This facile and universal strategy paves the way for the fabrication of diverse high-loading heterogeneous catalysts for broad applications.

Vanadium and tantalum doping of tin dioxide: a theoretical study

The increasing demand of efficient optoelectronic devices such as photovoltaics has created a great research interest in methods to manipulate the electronic and optical properties of all the layers of the device. Tin dioxide (SnO2), due to his charge transport capability, high stability and easy fabrication is the main electron transport layer in modern photovoltaics which have achieved a record efficiency. While the wide band gap of SnO2 makes it an effective electron transport layer, its potential for other energy applications such as photocatalysis is limited. To further improve is conductivity and reduce its bandgap, doping or co-doping with various elements has been proposed. In the present density functional theory (DFT) study, we focus on the investigation of vanadium (V) and tantalum (Ta) doped SnO2 both in the bulk and the surface. Here we focus on interstitial and substitutional doping aiming to leverage these modifications to enhance the density of states for energy application. These changes also have the potential to influence the optical properties of the material, such as absorption, and make SnO2 more versatile for photovoltaic and photocatalytic applications. The calculations show the formation of gap states near the band edges which are beneficial for the electron transition and in the case of Ta doping the lowest bandgap value is achieved. Interestingly, in the case of Ta interstitial, deep trap states are formed which depending of the application could be advantageous. Regarding the optical properties, we found that V doping significantly increases the refractive index of SnO2 while the absorption is generally improved in all the cases. Lastly, we investigate the electronic properties of the (110) surface of SnO2, and we discuss possible other applications due to surface doping. The present work highlights the importance of V and Ta doping for energy applications and sensor applications.

Attention-based solubility prediction of polysulfide and electrolyte analysis for lithium-sulfur batteries

During the continuous charge and discharge process in lithium-sulfur batteries, one of the next-generation batteries, polysulfides are generated in the battery's electrolyte, and impact its performance in terms of power and capacity by involving the process. The amount of polysulfides in the electrolyte could be estimated by the change of the Gibbs free energy of the electrolyte, [Formula: see text] in the presence of polysulfide. However, obtaining [Formula: see text] of the diverse mixtures of components in the electrolyte is a complex and expensive task that shows itself as a bottleneck in optimization of electrolytes. In this work, we present a machine-learning approach for predicting [Formula: see text] of electrolytes. The proposed architecture utilizes (1) an attention-based model (Attentive FP), a contrastive learning model (MolCLR) or morgan fingerprints to represent chemical components, and (2) transformers to account for the interactions between chemicals in the electrolyte. This architecture was not only capable of predicting electrolyte properties, including those of chemicals not used during training, but also providing insights into chemical interactions within electrolytes. It revealed that interactions with other chemicals relate to the logP and molecular weight of the chemicals.

Proton and molecular permeation through the basal plane of monolayer graphene oxide

Two-dimensional (2D) materials offer a prospect of membranes that combine negligible gas permeability with high proton conductivity and could outperform the existing proton exchange membranes used in various applications including fuel cells. Graphene oxide (GO), a well-known 2D material, facilitates rapid proton transport along its basal plane but proton conductivity across it remains unknown. It is also often presumed that individual GO monolayers contain a large density of nanoscale pinholes that lead to considerable gas leakage across the GO basal plane. Here we show that relatively large, micrometer-scale areas of monolayer GO are impermeable to gases, including helium, while exhibiting proton conductivity through the basal plane which is nearly two orders of magnitude higher than that of graphene. These findings provide insights into the key properties of GO and demonstrate that chemical functionalization of 2D crystals can be utilized to enhance their proton transparency without compromising gas impermeability.

Diffusion controlled electrochemical analysis of MoS2 and MOF derived metal oxide-carbon hybrids for high performance supercapacitors

In the context of emerging electric devices, the demand for advanced energy storage materials has intensified. These materials must encompass both surface and diffusion-driven charge storage mechanisms. While diffusion-driven reactions offer high capacitance by utilizing the bulk of the material, their effectiveness diminishes at higher discharge rates. Conversely, surface-controlled reactions provide rapid charge/discharge rates and high power density. To strike a balance between these attributes, we devised a tri-composite material, TiO2/Carbon/MoS2 (T10/MoS2). This innovative design features a highly porous carbon core for efficient diffusion and redox-active MoS2 nanosheets on the surface. Leveraging these characteristics, the T10/MoS2 composite exhibited impressive specific capacitance (436 F/g at 5 mV/s), with a significant contribution from the diffusion-controlled process (82%). Furthermore, our symmetrical device achieved a notable energy density of ~ 50 Wh/kg at a power density of 1.3 kW/kg. This concept holds promise for extending the approach to other Metal-Organic Framework (MOF) structures, enabling enhanced diffusion-controlled processes in energy storage applications.

Stabilizing lattice oxygen redox in layered sodium transition metal oxide through spin singlet state

Reversible lattice oxygen redox reactions offer the potential to enhance energy density and lower battery cathode costs. However, their widespread adoption faces obstacles like substantial voltage hysteresis and poor stability. The current research addresses these challenges by achieving a non-hysteresis, long-term stable oxygen redox reaction in the P3-type Na2/3Cu1/3Mn2/3O2. Here we show this is accomplished by forming spin singlet states during charge and discharge. Detailed analysis, including in-situ X-ray diffraction, shows highly reversible structural changes during cycling. In addition, local CuO6 Jahn-Teller distortions persist throughout, with dynamic Cu-O bond length variations. In-situ hard X-ray absorption and ex-situ soft X-ray absorption study, along with density function theory calculations, reveal two distinct charge compensation mechanisms at approximately 3.66 V and 3.99 V plateaus. Notably, we observe a Zhang-Rice-like singlet state during 3.99 V charging, offering an alternative charge compensation mechanism to stabilize the active oxygen redox reaction.

Design principles for sodium superionic conductors

Motivated by the high-performance solid-state lithium batteries enabled by lithium superionic conductors, sodium superionic conductor materials have great potential to empower sodium batteries with high energy, low cost, and sustainability. A critical challenge lies in designing and discovering sodium superionic conductors with high ionic conductivities to enable the development of solid-state sodium batteries. Here, by studying the structures and diffusion mechanisms of Li-ion versus Na-ion conducting solids, we reveal the structural feature of face-sharing high-coordination sites for fast sodium-ion conductors. By applying this feature as a design principle, we discover a number of Na-ion conductors in oxides, sulfides, and halides. Notably, we discover a chloride-based family of Na-ion conductors NaxMyCl6 (M = La-Sm) with UCl3-type structure and experimentally validate with the highest reported ionic conductivity. Our findings not only pave the way for the future development of sodium-ion conductors for sodium batteries, but also consolidate design principles of fast ion-conducting materials for a variety of energy applications.

Precise solid-phase synthesis of CoFe@FeOx nanoparticles for efficient polysulfide regulation in lithium/sodium-sulfur batteries

Complex metal nanoparticles distributed uniformly on supports demonstrate distinctive physicochemical properties and thus attract a wide attention for applications. The commonly used wet chemistry methods display limitations to achieve the nanoparticle structure design and uniform dispersion simultaneously. Solid-phase synthesis serves as an interesting strategy which can achieve the fabrication of complex metal nanoparticles on supports. Herein, the solid-phase synthesis strategy is developed to precisely synthesize uniformly distributed CoFe@FeOx core@shell nanoparticles. Fe atoms are preferentially exsolved from CoFe alloy bulk to the surface and then be carburized into a FexC shell under thermal syngas atmosphere, subsequently the formed FexC shell is passivated by air, obtaining CoFe@FeOx with a CoFe alloy core and a FeOx shell. This strategy is universal for the synthesis of MFe@FeOx (M = Co, Ni, Mn). The CoFe@FeOx exhibits bifunctional effect on regulating polysulfides as the separator coating layer for Li-S and Na-S batteries. This method could be developed into solid-phase synthetic systems to construct well distributed complex metal nanoparticles.

Energy transfer in N-component nanosystems enhanced by pulse-driven vibronic many-body entanglement

The processing of energy by transfer and redistribution, plays a key role in the evolution of dynamical systems. At the ultrasmall and ultrafast scale of nanosystems, quantum coherence could in principle also play a role and has been reported in many pulse-driven nanosystems (e.g. quantum dots and even the microscopic Light-Harvesting Complex II (LHC-II) aggregate). Typical theoretical analyses cannot easily be scaled to describe these general N-component nanosystems; they do not treat the pulse dynamically; and they approximate memory effects. Here our aim is to shed light on what new physics might arise beyond these approximations. We adopt a purposely minimal model such that the time-dependence of the pulse is included explicitly in the Hamiltonian. This simple model generates complex dynamics: specifically, pulses of intermediate duration generate highly entangled vibronic (i.e. electronic-vibrational) states that spread multiple excitons - and hence energy - maximally within the system. Subsequent pulses can then act on such entangled states to efficiently channel subsequent energy capture. The underlying pulse-generated vibronic entanglement increases in strength and robustness as N increases.