Three-dimensional ordered macroporous molybdenum doped NiCoP honeycomb electrode for two-step water electrolysis

Two-step alkaline water electrolysis is considered a safe and efficient method for producing hydrogen from renewable energy. Reversal of the current polarity in a bifunctional electrocatalyst used as a gas evolution electrode (GEE) in two-step water electrolysis can generate H₂/O₂ at different times and in different spaces. The design of a bifunctional electrocatalyst with high durability and excellent activity is imperative to achieving continuous, safe, and pure H₂ generation via two-step alkaline water electrolysis. Here, we present for the first time a novel 3D Mo-doped NiCo phosphide honeycomb electrocatalyst that was grown on nickel foam (3D Mo-NiCoP/NF) and fabricated using polystyrene as a template. The electrocatalyst exhibited extremely low overpotentials in both the hydrogen evolution reaction (HER; 117 mV at 10 mA/cm²) and the oxygen evolution reaction (OER; 344 mV at 100 mA/cm²). As a bifunctional electrocatalyst for two-step alkaline water electrolysis, the device had a 1.784 V cell voltage at 10 mA/cm², 95% decoupling efficiency, and ∼83% energy conversion efficiency. Taken together, the use of 3D Mo-NiCoP/NF as a GEE reduced the complexity and lowered the cost of the electrolyzer. The latter could be used to construct highly competitive water-splitting systems for continuous H₂ production and green energy harvesting.

Vacancy and doping engineering of Ni-based charge-buffer electrode for highly-efficient membrane-free and decoupled hydrogen/oxygen evolution

The realization of the membrane-free two-step water electrolysis is particularly important yet challenging for the low-cost and large-scale supply of hydrogen energy. In this effort, Co-doped Ni(OH)₂ nanosheets were successfully anchored onto the nickel foam (NF) substrate through the in-situ growth of metal-organic frame material and the subsequent alkali-etching technique. Using the well-regulated Co-doping Ni(OH)₂@NF electrodes as a charge mediator, electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were decoupled on time scales, thus affording a membrane-free two-step route for H₂ and O₂ productions. In this architecture, the first HER process on the cathode could be maintained for 1300 s at a current of 100 mA, while the corresponding Ni(OH)₂ charge mediator was simultaneously oxidized to NiOOH, with a decent cell voltage of 1.542 V. The subsequent OER process involved a reduction/regeneration of Ni(OH)₂ (from NiOOH to Ni(OH)₂) and an anodic O₂-production, with an operating voltage of 0.291 V. Moreover, the Ni-Zn battery assembled through the combination of NiOOH and Zn sheet could replace the second step of OER to achieve the coupling of continuous H₂-production and battery discharge, thus also providing a new way for hydrogen production without an external power supply. Experiment and theoretical calculations have shown that the cobalt-doping not only improved the conductivity of the charge-buffer electrode, but also shifted its redox potential cathodically and boosted the adsorption affinity of the buffer medium to OH^- ions, both contributing to promoted HER and OER activity. Therefore, this decoupled water electrolysis device affords a promising pathway to support the efficient conversion of renewables to hydrogen.

Alkyl side chain engineering enables high performance as-cast organic solar cells of over 17% efficiency

Achieving high-performance as-cast OSCs is crucial for industrialization in the future, owing to the advantages of better stability, environmental-friendly, and decreasing production cost. In this regard, we synthesized an A-DA'D-A type acceptor, Y6-eC6-BO, by shortening the straight alkyl side-chains on the thiophene position from C11 to C6 as well as lengthening the branched alkyl side-chains on the pyrrole position of Y6 to achieve a stronger crystallization and better miscibility than Y6. As a result, the corresponding chloroform-processed as-cast PM6: Y6-eC6-BO OSC showed a high PCE of 17.33%, which was one of the highest efficiencies of as-cast OSCs. And the as-cast PM6:Y6-eC6-BO OSCs processed from o-xylene displayed a PCE of 16.38%, as far as we know, this is among the highest efficiencies of non-halogenated-solvent processed as-cast OSCs. These results demonstrated tailoring the alkyl side-chain of NFAs is a feasible and simple approach to achieve high performance as-cast OSCs and provides guideline in molecular design in the future.

Multi-scale boron penetration toward stabilizing nickel-rich cathode

Nickel-rich layered oxides LiNi x Co y Mn1- x - y O2 (x ≥ 0.8) have been recognized as the preferred cathode materials to develop lithium-ion batteries with high energy density (>300 Wh kg-1). However, the poor cycling stability and rate capability stemming from intergranular cracks and sluggish kinetics hinder their commercialization. To address such issues, a multi-scale boron penetration strategy is designed and applied on the polycrystalline LiNi0.83Co0.11Mn0.06O2 particles that are pre-treated with pore construction. The lithium-ion conductive lithium borate in grain gaps functions as the grain binder that can bear the strain/stress from anisotropic contraction/expansion, and provides more pathways for lithium-ion diffusion. As a result, the intergranular cracks are ameliorated and the lithium-ion diffusion kinetics is improved. Moreover, the coating layer separates the sensitive cathode surface and electrolyte, helping to suppress the parasitic reactions and related gas evolution. In addition, the enhanced structural stability is acquired by strong B-O bonds with trace boron doping. As a result, the boron-modified sample with an optimized boron content of 0.5% (B5-NCM) exhibits a higher initial discharge capacity of 205.5 mAh g-1 at 0.1C (1C = 200 mA g-1) and improved capacity retention of 81.7% after 100 cycles at 1C. Furthermore, the rate performance is distinctly enhanced by high lithium-ion conductive LBO (175.6 mAh g-1 for B5-NCM and 154.6 mAh g-1 for B0-NCM at 5C).

Challenges and Solutions for Low-Temperature Lithium-Sulfur Batteries: A Review

The lithium-sulfur (Li-S) battery is considered to be one of the attractive candidates for breaking the limit of specific energy of lithium-ion batteries and has the potential to conquer the related energy storage market due to its advantages of low-cost, high-energy density, high theoretical specific energy, and environmental friendliness issues. However, the substantial decrease in the performance of Li-S batteries at low temperatures has presented a major barrier to extensive application. To this end, we have introduced the underlying mechanism of Li-S batteries in detail, and further concentrated on the challenges and progress of Li-S batteries working at low temperatures in this review. Additionally, the strategies to improve the low-temperature performance of Li-S batteries have also been summarized from the four perspectives, such as electrolyte, cathode, anode, and diaphragm. This review will provide a critical insight into enhancing the feasibility of Li-S batteries in low-temperature environments and facilitating their commercialization.

Control and regulation of the performance of fullerene-based dye-sensitized solar cells with a D-D-A structure by external electric fields

We investigated the modulating effect of an electric field (F_ext) on the photovoltaic properties of triphenylamine-based sensitizers with a D-D-A structure and compared the photovoltaic parameters at different electric field intensities. The results show that F_ext can effectively adjust the photoelectric properties of the molecule. From the change of the parameters that measures the degree of electron delocalization, it can be seen that the F_ext can effectively strengthen the electronic communication and promote the charge transfer process within the molecule. And the dye molecule under a strong F_ext has a narrower energy gap, more favorable injection, regeneration driving force and a larger conduction band energy level shift, which ensures that the dye molecule can exhibit larger V_oc and J_sc under a strong F_ext. The results of calculations on the photovoltaic parameters of dye molecules show that dye molecules can exhibit better photovoltaic performance under the action of F_ext, which provides beneficial predictions and prospects for the development of highly efficient DSSCs.

A three-dimensional interconnected molybdenum disulfide/multi-walled carbon nanotubes cathode with enlarged interlayer spacing for aqueous zinc-ion storage

Layered molybdenum disulfide (MoS₂) shows tremendous prospect as cathode material for aqueous zinc-ion batteries (AZIBs) due to the two-dimensional zinc ions (Zn²⁺) diffusion channels and tunable interlayer spacing. However, it is subjected to sluggish insertion/extraction kinetics, inferior electronic conductivity and inadequate active capacities. Herein, a three-dimensional (3D) interconnected MoS₂/multi-walled carbon nanotubes (MWCNTs) framework is proposed to address these issues. Importantly, the MWCNTs cores offer interconnection routes for fast electrons and zinc ions transport, the expanded spacing of MoS₂ interlayer with 1.05 nm can facilitate rapid Zn²⁺ intercalation/extraction, and the confined MoS₂ layers in inner MWCNTs can mitigate the agglomeration and restacking of MoS₂ nanosheets. Benefitting from the confined structural configuration, sufficient active surface and 3D structural stability, the MoS₂/MWCNTs as AZIBs cathode delivers a large initial reversible capacity of 218.3 mAh/g and high coulombic efficiency of 78.2 % at 0.1 A/g. Additionally, the 3D interconnected cathode maintains nearly intact structure after a fierce galvanostatic charge/discharge process, resulting in large retained capacities of 126.3 mAh/g at 1 A/g after 650 cycles and 101.1 mAh/g at 3 A/g after 1000 cycles. This work offers a novel strategy for the structure design of two-dimensional materials to develop high-performance cathodes for AZIBs.

The local impacts of coal and oil power plant retirements on air pollution and cardiorespiratory health in California: An application of generalized synthetic control method

BACKGROUND

This study capitalized on coal and oil facility retirements to quantify their potential effects on fine particulate matter (PM2.5) concentrations and cardiorespiratory hospitalizations in affected areas using a generalized synthetic control method.

METHODS

We identified 11 coal and oil facilities in California that retired between 2006 and 2013. We classified zip code tabulation areas (ZCTA) as exposed or unexposed to a facility retirement using emissions information, distance, and a dispersion model. We calculated weekly ZCTA-specific PM2.5 concentrations based on previously estimated daily time-series PM2.5 concentrations from an ensemble model, and weekly cardiorespiratory hospitalization rates based on hospitalization data collected by the California Department of Health Care Access and Information. We estimated the average differences in weekly average PM2.5 concentrations and cardiorespiratory hospitalization rates in four weeks after each facility retirement between the exposed ZCTAs and the synthetic control using all unexposed ZCTAs (i.e., the average treatment effect among the treated [ATT]) and pooled ATTs using meta-analysis. We conducted sensitivity analyses to consider different classification schemes to distinguish exposed from unexposed ZCTAs, including aggregating outcomes with different time intervals and including a subset of facilities with reported retirement date confirmed via emission record.

RESULTS

The pooled ATTs were 0.02 μg/m3 (95% confidence interval (CI): -0.25 to 0.29 μg/m3) and 0.34 per 10,000 person-weeks (95%CI: -0.08 to 0.75 per 10,000 person-weeks) following the facility closure for weekly PM2.5 and cardiorespiratory hospitalization rates, respectively. Our inferences remained the same after conducting sensitivity analyses.

CONCLUSIONS

We demonstrated a novel approach to study the potential benefits associated with industrial facility retirements. The declining contribution of industrial emissions to ambient air pollution in California may explain our null findings. We encourage future research to replicate this work in regions with different industrial activities.

Study on performance and mechanisms of anaerobic oxidation of methane-microbial fuel cells (AOM-MFCs) with acetate-acclimatizing or formate-acclimatizing electroactive culture

Anaerobic oxidation of methane-microbial fuel cells with acetate-acclimatizing or formate-acclimatizing electroactive culture (A-AOM-MFC and F-AOM-MFC) were designed and operated at room temperature in this study to evaluate and explore the electrochemical performance and mechanisms of methane conversion and electricity generation. The results indicated that A-AOM-MFC output a higher voltage (0.526 ± 0.001 V) and F-AOM-MFC started up in a shorter time (51 d), resulting from different mechanisms of methane-electrogen caused by discrepant microbial alliances. Specifically, in A-AOM-MFC, acetoclastic methanogens (e.g., Methanosaeta) converted methane into intermediates (e.g., acetate) through reversing methanogenesis and carried out the direct interspecific electron transfer (DIET) with Geobacter-predominated electricigens which can oxidize the intermediates to carbon dioxide and transfer electrons to the electrodes. Differently, the intermediate-dependent extracellular electron transfer (EET) existed in F-AOM-MFC between hydro-methanogens (e.g., Methanobacterium) and electricigens (e.g., Geothrix), which was more difficult than DIET. Additionally, hydro-methanogens metabolized methane to produce formate-dominant intermediates more quickly.

Preparation of long-term cycling stable ni-rich concentration-gradient NCMA cathode materials for li-ion batteries

Nickel-rich (Ni > 90 %) cathodes are regarded as one of the most attractive because of their high energy density, despite their poor stability and cycle life. To improve their performance, in this study we synthesized a double concentration-gradient layered Li[Ni_0.90Co_0.04Mn_0.03Al_0.03]O₂ oxide (CG-NCMA) using a continuous co-precipitation Taylor-Couette cylindrical reactor (TCCR) with a Ni-rich-core, an Mn-rich surface, and Al on top. The concentration-gradient morphology was confirmed through cross-sectional EDX line scanning. The as-synthesized sample exhibited excellent electrochemical performance at high rates (5C/10C), as well as cyclability (91.5 % after 100 cycles and 70.3 % after 500 cycles at 1C), superior to that (83.4 % and 47.6 %) of its non-concentration-gradient counterpart (UC-NCMA). The Mn-rich surface and presence of Al helped the material stay structurally robust, even after 500 cycles, while also suppressing side reactions between the electrode and electrolyte, resulting in better overall electrochemical performance. These enhancements in performance were studied using TEM, SEM, in-situ-XRD, XPS, CV, EIS and post-mortem analyses. This synthetic method enables the highly scalable production of CG-NCMA samples with two concentration-gradient structures for practical applications in Li-ion batteries.

Two-dimensional transition metal carbide (Ti0.5V0.5)3C2Tx MXene as high performance electrode for flexible supercapacitor

MXenes have gained widespread interest in flexible supercapacitor due to their rich electrochemical activity and free-standing electrode structure. However, it has been a challenge to obtain an electrode with high (mass and volumetric) specific capacitance, high rate and long cycle life simultaneously. Herein, we have prepared a novel few-layer double transition metal carbide (Ti_0.5V_0.5)₃C₂T_x MXene. Multivalent V atoms with high electrochemical activity were constructed in stable M₃C₂-type MXene to obtain the (Ti_0.5V_0.5)₃C₂T_x electrode with excellent performance in flexible supercapacitors. The (Ti_0.5V_0.5)₃C₂T_x film has an excellent specific capacitance of 387F g^-1 (1625 mF cm^-3) at 1.0 A g^-1, and 267 F g^-1 (1121 mF cm^-3) even at a high current density of 20.0 A g^-1, demonstrating superior rate performance (69%). Moreover, the capacitance of the (Ti_0.5V_0.5)₃C₂T_x film remains stable during 100,000 cycles. The symmetric supercapacitor assembled using (Ti_0.5V_0.5)₃C₂T_x film has high energy and power densities, up to 5.6 Wh kg^-1 and 5210.3 W kg^-1. And the all-solid-state (Ti_0.5V_0.5)₃C₂T_x flexible SC maintains stable electrochemical performance after 200 bending cycles. This work shows the huge potential of (Ti_0.5V_0.5)₃C₂T_x in flexible supercapacitor, and provides a new idea for the design of high performance flexible electrodes.

Electrolytes with Solvating Inner Sheath Engineering for Practical Na-S Batteries

Sodium-sulfur (Na-S) batteries with durable Na-metal stability, shuttle-free cyclability, and long lifespan are promising to large-scale energy storages. However, meeting these stringent requirements poses huge challenges with the existing electrolytes. Herein, a localized saturated electrolyte (LSE) is proposed with 2-methyltetrahydrofuran (MeTHF) as an inner sheath solvent, which represents a new category of electrolyte for Na-S system. Unlike the traditional high concentration electrolytes, the LSE is realized with a low salt-to-solvent ratio and low diluent-to-solvent ratio, which pushes the limit of localized high concentration electrolyte (LHCE). The appropriate molecular structure and solvation ability of MeTHF regulate a saturated inner sheath, which features a reinforced coordination of Na⁺ to anions, enlarged Na⁺ -solvent distance, and weakened anion-diluent interaction. Such electrolyte configuration is found to be the key to build a sustainable interphase and a quasi-solid-solid sulfur redox process, making a dendrite-inhibited and shuttle-free Na-S battery possible. With this electrolyte, pouch cells with decent cycling performance under rather demanding conditions are demonstrated.

Heterostructure engineering and ultralow Pt-loaded multicomponent nanocage for efficient electrocatalytic oxygen evolution

Developing highly efficient electrocatalysts based on appropriate heterojunction engineering and electronic structure modification for the oxygen evolution reaction (OER) has been extensively recognized as an effective approach to increase the efficiency of water splitting. Herein, ultralow Pt-loaded (1 %) NiCoFeP@NiCoFe-PBA hollow nanocages with well-defined heterointerfaces and modified electronic environment are successfully fabricated. As expected, the obtained Pt-NiCoFeP@NiCoFe-PBA exhibits outstanding performance with a low overpotential of 255 mV at 10 mA cm^-2 and a small Tafel slope of 57.2 mV dec^-1. More specifically, the highly open three-dimensional structure, exquisite interior voids and abundant surface defects endow Pt-NiCoFeP@NiCoFe-PBA nanocages with more electrochemical active sites. Meanwhile, experimental results and mechanism studies also reveal that the construction of heterogeneous interfaces as well as incorporation of noble metals could readily induce strong synergistic effects and significantly tailor electronic configurations to optimize the binding energy of the intermediates, thereby achieving prominent OER performance.

Emerging indoor photovoltaics for self-powered and self-aware IoT towards sustainable energy management

As the number of Internet of Things devices is rapidly increasing, there is an urgent need for sustainable and efficient energy sources and management practices in ambient environments. In response, we developed a high-efficiency ambient photovoltaic based on sustainable non-toxic materials and present a full implementation of a long short-term memory (LSTM) based energy management using on-device prediction on IoT sensors solely powered by ambient light harvesters. The power is supplied by dye-sensitised photovoltaic cells based on a copper(ii/i) electrolyte with an unprecedented power conversion efficiency at 38% and 1.0 V open-circuit voltage at 1000 lux (fluorescent lamp). The on-device LSTM predicts changing deployment environments and adapts the devices' computational load accordingly to perpetually operate the energy-harvesting circuit and avoid power losses or brownouts. Merging ambient light harvesting with artificial intelligence presents the possibility of developing fully autonomous, self-powered sensor devices that can be utilized across industries, health care, home environments, and smart cities.

Decarbonizing real estate portfolios considering optimal retrofit investment and policy conditions to 2050

Retrofitting existing buildings is crucial for achieving Net Zero emissions. Institutional real estate owners play a key role because of their significant ownership, especially of large buildings. We utilize an interdisciplinary approach to evaluate cost-optimal decarbonization conditions for three Swiss real estate portfolios owned by a global institutional investor. We leverage a bottom-up optimization framework for building asset retrofitting, scaled to the portfolio-level, to study the effect of policy scenarios and implementations. Results indicate that achieving Net Zero necessitates significant investments, largely through thermal energy efficiency measures and low-CO₂ energy systems, as early as possible to avoid locked-in emissions. Owners will be challenged to smooth long-term capital investments, pointing to a potential liquidity crisis. Consequently, hard-to-decarbonize assets are unable to reach regulatory benchmarks largely because of lingering embodied emissions. To lower transition risk, we recommend that policymakers move toward average CO₂ benchmarks at the real estate portfolio-level, emulating automotive fleets.

A novel and accurate deep learning-based Covid-19 diagnostic model for heart patients

Using radiographic changes of COVID-19 in the medical images, artificial intelligence techniques such as deep learning are used to extract some graphical features of COVID-19 and present a Covid-19 diagnostic tool. Differently from previous works that focus on using deep learning to analyze CT scans or X-ray images, this paper uses deep learning to scan electro diagram (ECG) images to diagnose Covid-19. Covid-19 patients with heart disease are the most people exposed to violent symptoms of Covid-19 and death. This shows that there is a special, unclear relation (until now) and parameters between covid-19 and heart disease. So, as previous works, using a general diagnostic model to detect covid-19 from all patients, based on the same rules, is not accurate as we prove later in the practical section of our paper because the model faces dispersion in the data during the training process. So, this paper aims to propose a novel model that focuses on diagnosing accurately Covid-19 for heart patients only to increase the accuracy and to reduce the waiting time of a heart patient to perform a covid-19 diagnosis. Also, we handle the only one existed dataset that contains ECGs of Covid-19 patients and produce a new version, with the help of a heart diseases expert, which consists of two classes: ECGs of heart patients with positive Covid-19 and ECGs of heart patients with negative Covid-19 cases. This dataset will help medical experts and data scientists to study the relation between Covid-19 and heart patients. We achieve overall accuracy, sensitivity and specificity 99.1%, 99% and 100%, respectively.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11760-023-02561-8.

Construction of 3D copper-chitosan-gas diffusion layer electrode for highly efficient CO2 electrolysis to C2+ alcohols

High-rate electrolysis of CO₂ to C₂₊ alcohols is of particular interest, but the performance remains far from the desired values to be economically feasible. Coupling gas diffusion electrode (GDE) and 3D nanostructured catalysts may improve the efficiency in a flow cell of CO₂ electrolysis. Herein, we propose a route to prepare 3D Cu-chitosan (CS)-GDL electrode. The CS acts as a "transition layer" between Cu catalyst and the GDL. The highly interconnected network induces growth of 3D Cu film, and the as-prepared integrated structure facilitates rapid electrons transport and mitigates mass diffusion limitations in the electrolysis. At optimum conditions, the C₂₊ Faradaic efficiency (FE) can reach 88.2% with a current density (geometrically normalized) as high as 900 mA cm^-2 at the potential of -0.87 V vs. reversible hydrogen electrode (RHE), of which the C₂₊ alcohols selectivity is 51.4% with a partial current density of 462.6 mA cm^-2, which is very efficient for C₂₊ alcohols production. Experimental and theoretical study indicates that CS induces growth of 3D hexagonal prismatic Cu microrods with abundant Cu (111)/Cu (200) crystal faces, which are favorable for the alcohol pathway. Our work represents a novel example to design efficient GDEs for electrocatalytic CO₂ reduction (CO₂RR).

Significantly enhanced photothermal catalytic CO2 reduction over TiO2/g-C3N4 composite with full spectrum solar light

Using solar energy to drive catalytic conversion of CO₂ into value-added chemicals has great potential to alleviate the global energy shortage and anthropogenic climate change. Herein, a "hitting three birds with one stone" strategy was reported to prepared boron-doped g-C₃N₄/TiO_2-x composite (BCT) by a one-step thermal reduction process. A series of characterizations showed that the composite catalyst has extended full-spectrum absorption, rapid photogenerated charge separation, and outstanding CO₂ photoreduction performance (265.2 μmol g^-1h^-1), which is 7.5 and 9.2 times higher than that of pure TiO₂ and g-C₃N₄, respectively. In addition, the CO₂ conversion rate can be further increased to 345.1 μmol g^-1h^-1 at 70 °C due to its excellent photothermal conversion. Mechanistic studies reveal that synergistic effects alter the charge density distribution, thereby lowering the energy barrier for CO₂ conversion by adsorbing and activating CO₂ molecules_. This work provides a novel three-in-one integrated strategy for fabricating high-efficiency catalysts.

Cobalt-free nickel-rich cathode materials based on Al/Mg co-doping of LiNiO2 for lithium ion battery

To develop Co-free LiNiO₂-based layered cathode materials is crucial for meeting the demands of the lithium-ion batteries with high energy density, long cycling life, and low cost. Herein, the LiNi_1-x-yAl_xMg_yO₂ materials are synthesized by the solid-solid interface elemental interdiffusion strategy. It is elucidated that the Mg²⁺ and Al³⁺ ions are mainly doped in the Li slabs and transition metal slabs, respectively, leading to the alteration of the crystal lattice. Furthermore, the incorporation of the Mg²⁺ ions may induce more Ni²⁺ ions formed in the transition metal slabs, which would have great impact on the electrochemical performance of the materials. The LiNi_1-x-yAl_xMg_yO₂ materials with optimized Mg/Al co-doping exhibit much better electrochemical performance than the pristine LiNiO₂ and Al-doped LiNiO₂ materials, including cycling stability and rate capability. The in-situ XRD characterization and structural analysis show that stabilization of the crystal structure, preservation of the integrity of the secondary particles, and enlargement of the interlayer spacing by the Mg/Al co-doping are the main factors responsible for the superior performance of the materials. The Mg/Al co-doping strategy might be the promising approach for the design of the cobalt-free nickel-rich materials.

Electrochemical properties and facile preparation of hollow porous V2O5 microspheres for lithium-ion batteries

Vanadium pentoxide (V₂O₅) has shown great potential to be used in lithium-ion batteries (LIBs), but it has limited applications because it has cycle instability and poor rate capability, and its lithiation mechanism is not well understood. In this work, hollow porous V₂O₅ microspheres (HPVOM) were obtained by a facile poly(vinylpyrrolidone) and ethylene glycol-assisted soft-template solvothermal method. Half cells with HPVOM exhibited good capacity, rate capability, and stability, delivering 407.9 mAh g^-1 at 1.0 A g^-1 after 700 cycles. Furthermore, a LiFePO₄/HPVOM full cell had a discharge capacity of 109.9 mAh g^-1 after 150 cycles at 0.1 A g^-1. Using an equivalent circuit model (ECM) and distribution of relaxation times (DRT), we found that the charge-transfer (including the solid-state interface resistance) and bulk resistances varied regularly with the charge/discharge state, while the electrolyte resistance was largely maintained. The bulk resistance finally vanished, indicative of dynamic activation. The method used to prepare the hollow microspheres, as well as the display of electrode kinetics via ECM and DRT, could be broadly applied in developing efficient electrodes for LIBs.

Structurally integrated asymmetric polymer electrolyte with stable Janus interface properties for high-voltage lithium metal batteries

Solid-state polymer electrolytes are outstanding candidates for next-generation lithium metal batteries in the realm of high specific energy densities, high safeties and tight contact with electrodes. However, their applications are still hindered by the limitations that no single polymer is electrochemically stable with the oxidizing high-voltage cathode and the highly reductive Li anode, simultaneously. Herein, a bilayer asymmetric polymer electrolyte (SL-SPE) without accessional interface resistance that using poly (ethylene glycol) diacrylate (PEGDA) as a "bridge" to connect the sulfonyl (OS = O)-contained oxidation-tolerated layer and polyether-derived reduction-tolerated layer (SPE), is proposed and synthesized by sequential two-step UV polymerizations. SL-SPE can provide widened electrochemical stability window up to 5 V, while simultaneously deploying a stable Janus interface property. Eventually, the superior high-voltage (4.4 V) cycling durability can be displayed in LiNi_0.6Co_0.2Mn_0.2O₂|SL-SPE|Li batteries. This finding provides a bran-new idea for designing multifunctional polymer electrolytes in the application of solid-state batteries.

"Thiol-ene" crosslinked polybenzimidazoles anion exchange membrane with enhanced performance and durability

To address the "trade-off" between conductivity and stability of anion exchange membranes (AEMs), we developed a series of crosslinked AEMs by using polybenzimidazole with norbornene (cPBI-Nb) as backbone and the crosslinked structure was fabricated by adopting click chemical between thiol and vinyl-group. Meanwhile, the hydrophilic properties of the dithiol cross-linker were regulated to explore the effect for micro-phase separation morphology and hydroxide ion conductivity. As result, the AEMs with hydrophilic crosslinked structure (PcPBI-Nb-C2) not only had apparent micro-phase separation morphology and high OH^- conductivity of 105.54 mS/cm at 80 °C, but also exhibited improved mechanical properties, dimensional stability (swelling ratio < 15%) and chemical stability (90.22 % mass maintaining in Fenton's reagent at 80 °C for 24 h, 78.30 % conductivity keeping in 2 M NaOH at 80 °C for 2016 h). In addition, the anion exchange membranes water electrolysis (AEMWEs) using PcPBI-Nb-C2 as AEMs achieved the current density of 368 mA/cm² at 2.1 V and the durability over 500 min operated at 150 mA/cm² under 60 °C. Therefore, this work paves the way for constructing AEMs by introduction of norbornene into polybenzimidazole and formation of hydrophilic crosslinked structure based on "thiol-ene".

Zn and N co-doped three-dimensional honeycomb-like carbon featured with interconnected nano-pools for dendrite-free zinc anode

The zinc-ion battery (ZIB) has been extensively researched as one of the promising electrochemical power sources. However, the problem of Zn-dendrite formation during repeated plating and stripping process seriously hinders the development of ZIBs. Herein, three-dimensional (3D) honeycomb-like porous carbon (HPC) with co-doping of zinc and nitrogen is prepared through confining growth of nanoscale zeolite imidazole framework-8 (ZIF-8) on the well-designed nano-pools walls of HPC followed by pyrolysis at 600 ℃ to obtain the final product ZnN/HPC-600, which exhibits large surface area and abundant zincophilic interfaces, ensuring homogeneous distribution of electronic field and low polarization during cycling process. Importantly, ZnN/HPC-600 facilitates the uniform distribution and migration of Zn²⁺ in this nano-pools structure, avoiding the growth of dendritic Zn crystal during charging stage. The symmetric and asymmetric cells with Zn/ZnN/HPC-600 anodes are assembled, demonstrating excellent cycling reversibility, good rate performance and long-term stability. Besides, a Zn||MnO₂ full cell with Zn/ZnN/HPC-600 anode also exhibits robust cycling stability, fast reaction kinetics and almost 100 % coulombic efficiency. This work offers a novel and efficient carbonaceous nano-pools strategy to realize dendrite-free zinc anode in ZIBs.

Revealing the activity origin of ultrathin nickel metal-organic framework nanosheet catalysts for selective electrochemical nitrate reduction to ammonia: Experimental and density functional theory investigations

The electrochemical nitrate reduction reaction (NitRR) affords a sustainable way for nitrate mitigation and ammonia synthesis, but there are still some problems such as poor nitrate conversion, low ammonia selectivity, and slow reaction kinetics. A clear structure-performance relationship is essential for designing efficient catalysts and understanding the reaction mechanisms. Herein, ultrathin nickel metal-organic framework (Ni-MOF) nanosheets supported on Ni foam featuring a well-defined stable structure, large electrochemically active surface area, and low electron transport resistance were prepared by a one-step solvothermal process. At -1.4 V, the nitrate reduction, rate constant, ammonia selectivity, and yield reached 96.4%, 0.448 h^-1, 80%, and 110.13 ug·h^-1·cm^-2, respectively. Experimental and theoretical studies demonstrated that the hydroxyl-ligated Ni atoms exhibited higher nitrate adsorption properties and lower activation energy towards NitRR compared to carboxylic acid-ligated Ni atoms. Mechanism investigations revealed a nitrate-to-ammonia reaction pathway involving multiple intermediate species on Ni-MOF nanosheet catalysts. This work offers a new avenue to construct highly efficient electrocatalysts for the selective transformation of nitrate to valuable ammonia.

Three-dimensional polyimide nanofiber framework reinforced polymer electrolyte for all-solid-state lithium metal battery

The replacement of traditional liquid electrolytes with polyethylene oxide (PEO) based composite polymer electrolytes (CPEs) is an important strategy to address the current flammability and explosiveness of lithium batteries since PEO CPEs have high flexibility, excellent processability and moderate cost. However, the insufficient ionic conductivity and inferior mechanical strength of PEO CPEs do not suit the operating requirements of all-solid-state lithium metal batteries at room temperature. Herein, three-dimensional (3D) framework composed of interweaved high-modulus polyimide (PI) nanofibers along with functional succinonitrile (SN) plasticizers are employed to synergistically reinforce the ionic conductivity and mechanical strength of PEO CPEs. Impressively, benefitting from the synergistic effects of 3D PI framework and SN plasticizer, PI-PEO-SN CPEs exhibits high ionic conductivity of 1.03 × 10^-4 S cm^-1 at 30 °C, remarkable tensile strength of 4.52 MPa, and superior Li dendrites blocking ability (>400 h at 0.1 mA cm^-2). Such favorable features of PI-PEO-SN CPEs endow LiFePO₄/PI-PEO-SN/Li solid-state prototype cells with high specific capacity (151.2 mA h g^-1 at 0.2 C), long cycling lifespan (>150 cycles with 91.7 % capacity retention), and superior operating safety even under bending, folding and cutting harsh conditions. This work will pave the avenues to design and fabricate new high-performance PEO CPEs for the high energy density and safety all-solid-state batteries.

Local hydrophobicity allows high-performance electrochemical carbon monoxide reduction to C2+ products

While CO can already be produced at industrially relevant current densities via CO₂ electrolysis, the selective formation of C₂₊ products seems challenging. CO electrolysis, in principle, can overcome this barrier, hence forming valuable chemicals from CO₂ in two steps. Here we demonstrate that a mass-produced, commercially available polymeric pore sealer can be used as a catalyst binder, ensuring high rate and selective CO reduction. We achieved above 70% faradaic efficiency for C₂₊ products formation at j = 500 mA cm^-2 current density. As no specific interaction between the polymer and the CO reactant was found, we attribute the stable and selective operation of the electrolyzer cell to the controlled wetting of the catalyst layer due to the homogeneous polymer coating on the catalyst particles' surface. These results indicate that sophistically designed surface modifiers are not necessarily required for CO electrolysis, but a simpler alternative can in some cases lead to the same reaction rate, selectivity and energy efficiency; hence the capital costs can be significantly decreased.

Origin of dendrite-free lithium deposition in concentrated electrolytes

The electrolyte solvation structure and the solid-electrolyte interphase (SEI) formation are critical to dictate the morphology of lithium deposition in organic electrolytes. However, the link between the electrolyte solvation structure and SEI composition and its implications on lithium morphology evolution are poorly understood. Herein, we use a single-salt and single-solvent model electrolyte system to systematically study the correlation between the electrolyte solvation structure, SEI formation process and lithium deposition morphology. The mechanism of lithium deposition is thoroughly investigated using cryo-electron microscopy characterizations and computational simulations. It is observed that, in the high concentration electrolytes, concentrated Li⁺ and anion-dominated solvation structure initiate the uniform Li nucleation kinetically and favor the decomposition of anions rather than solvents, resulting in inorganic-rich amorphous SEI with high interface energy, which thermodynamically facilitates the formation of granular Li. On the contrary, solvent-dominated solvation structure in the low concentration electrolytes tends to exacerbate the solvolysis process, forming organic-rich mosaic SEI with low interface energy, which leads to aggregated whisker-like nucleation and growth. These results are helpful to tackle the long-standing question on the origin of lithium dendrite formation and guide the rational design of high-performance electrolytes for advanced lithium metal batteries.

One-step rapid synthesis of Ni0.5Co0.5-CPO-27 nanorod array with oxygen vacancies based on DBD microplasma: As an effective non-enzymatic glucose sensor for beverage and human serum

The rational design of high-efficiency catalysts for non-enzymatic glucose sensing is extremely important for the timely and effective monitoring of glucose content in beverages and human blood. A 3D bimetallic organic framework (Coordination Polymer of Oslo, CPO) nanorod array with oxygen vacancies was green fabricated on carbon cloth (Ni_0.5Co_0.5-CPO-27 NRA/CC) using dielectric barrier discharge (DBD) microplasma for the first time. Density functional theory (DFT) calculations demonstrated that the oxygen vacancy of Ni_0.5Co_0.5-CPO-27 can be effectively induced under DBD microplasma conditions. Based on the 3D nanorod arrays with rich oxygen vacancies and bimetallic synergistic effects, as a non-enzyme glucose sensor, the Ni_0.5Co_0.5-CPO-27 electrode exhibited a sensitivity of 8499.5 μA L/mmol cm^-2 and 3239.2 μA L/mmol cm^-2 and a limit of detection (LOD) of 0.16 μmol/L (S/N = 3). It has been successfully applied to the determination of glucose levels in real samples such as cola, green tea and human serum.

Skin-interfaced electronics: A promising and intelligent paradigm for personalized healthcare

Skin-interfaced electronics (skintronics) have received considerable attention due to their thinness, skin-like mechanical softness, excellent conformability, and multifunctional integration. Current advancements in skintronics have enabled health monitoring and digital medicine. Particularly, skintronics offer a personalized platform for early-stage disease diagnosis and treatment. In this comprehensive review, we discuss (1) the state-of-the-art skintronic devices, (2) material selections and platform considerations of future skintronics toward intelligent healthcare, (3) device fabrication and system integrations of skintronics, (4) an overview of the skintronic platform for personalized healthcare applications, including biosensing as well as wound healing, sleep monitoring, the assessment of SARS-CoV-2, and the augmented reality-/virtual reality-enhanced human-machine interfaces, and (5) current challenges and future opportunities of skintronics and their potentials in clinical translation and commercialization. The field of skintronics will not only minimize physical and physiological mismatches with the skin but also shift the paradigm in intelligent and personalized healthcare and offer unprecedented promise to revolutionize conventional medical practices.

Biophotovoltaics: Recent advances and perspectives

Biophotovoltaics (BPV) is a clean power generation technology that uses self-renewing photosynthetic microorganisms to capture solar energy and generate electrical current. Although the internal quantum efficiency of charge separation in photosynthetic microorganisms is very high, the inefficient electron transfer from photosystems to the extracellular electrodes hampered the electrical outputs of BPV systems. This review summarizes the approaches that have been taken to increase the electrical outputs of BPV systems in recent years. These mainly include redirecting intracellular electron transfer, broadening available photosynthetic microorganisms, reinforcing interfacial electron transfer and design high-performance devices with different configurations. Furthermore, three strategies developed to extract photosynthetic electrons were discussed. Among them, the strategy of using synthetic microbial consortia could circumvent the weak exoelectrogenic activity of photosynthetic microorganisms and the cytotoxicity of exogenous electron mediators, thus show great potential in enhancing the power output and prolonging the lifetime of BPV systems. Lastly, we prospected how to facilitate electron extraction and further improve the performance of BPV systems.