Conjugated Microporous Polymers-Based Catalytic Membranes with Hierarchical Channels for High-Throughput Removal of Micropollutants.

Engineering a catalytic membrane capable of efficiently removing emerging organic microcontaminants under ultrahigh flux conditions is of significance for water purification. Herein, drawing inspiration from the functional attributes of lymphatic vessels involved in immunosurveillance and fluid transport with minimal energy consumption, a novel hierarchical porous catalytic membrane is engineered. This membrane, based on an innovative nitrogen-rich conjugated microporous polymer (polytripheneamine, PTPA), is synthesized using an electrospinning coupled in situ polymerization approach. The resulting bioinspired membrane with hierarchical channels comprises a thin layer (≈1.7 µm) of crosslinked PTPA nanoparticles covering the interconnected electrospun nanofibers. This unique design creates an intrinsic microporous angstrom-confined system capable of activating peroxymonosulfate (PMS) to generate 98.7% singlet oxygen (1O2), enabling durable and highly efficient degradation of microcontaminants. Additionally, the presence of a thin layer of mesoporous structure between PTPA nanoparticles and macroporous channels within the interwoven nanofibers enhances mass transfer efficiency and facilitates high flux rates. Notably, the prepared hierarchical porous organic catalytic membrane demonstrates enduring high-efficiency degradation performance with a superior permeance (>95% and >2500 L m-2 h-1 bar-1) sustained over 100 h. This work introduces an innovative pathway for the design of high-performance catalytic membranes for the removal of emerging organic microcontaminants.

Laser-Scribed Battery Electrodes for Ultrafast Zinc-Ion Energy Storage.

Aqueous Zn batteries are promising for large-scale energy storage applications but are plagued by the lack of high-performance cathode materials that enable high specific capacity, ultrafast charging, and outstanding cycling stability. In this work, we design a laser-scribed nano-vanadium oxide (LNVO) cathode that can simultaneously achieve these properties. Our material stores charge through Faradaic redox reactions on/near the surface at fast rates owing to the small grain size (2-6 nm) of vanadium oxide and interpenetrating three-dimensional (3D) graphene network, displaying a surface-controlled capacity contribution (90%-98%). Multiple characterization techniques unambiguously reveal that zinc and hydronium ions co-insert with minimal LNVO lattice change upon cycling. As a result, we demonstrate that a high specific capacity of 553 mAh g-1 can be achieved by the LNVO/Zn system at 0.1 A g-1 , and an impressive 264 mAh g-1 capacity can be retained at 100 A g-1 with a 10 s charge/discharge cycle, showing excellent rate capability. The LNVO/Zn is also capable of reaching >90% capacity retention after 3,000 cycles at a high rate of 30 A g-1, as well as achieving both high energy (369 Wh kg-1) and power densities (56,306 W kg-1). Moreover, the LNVO cathode retains its excellent cycling performance when integrated into quasi-solid-state pouch cells, further demonstrating mechanical stability and its potential for practical application in wearable and grid-scale applications. This article is protected by copyright. All rights reserved.

A nanoengineered vanadium oxide composite as a high-performance anode for aqueous Li-ion hybrid batteries.

Aqueous lithium-ion batteries (LIBs) have received increasing attention as a promising solution for stationary energy storage systems due to their low environmental impact, non-flammability and low cost. Despite recent progress in electrolyte development and cathode manufacturing, the lack of anode materials with high specific capacity presents difficult challenges for a wide range of applications. In this study, we propose a novel synthetic strategy to fabricate a pseudocapacitive V2O5/graphene composite as a highly functional anode material for aqueous LIBs. The designed synthesis combines a fast laser-scribing step with controlled calcination to tune the morphology and oxidation state of the electrochemically active vanadium oxide species while obtaining a highly conductive graphene scaffold. The optimized V2O5/graphene anode shows an outstanding specific capacity of 158 mA h g-1 in three-electrode measurements. When the V2O5/graphene anode is paired with an LiMn2O4 cathode, the charge storage mechanism of the full cell is revealed to be dominantly surface-controlled, resulting in remarkable rate performance. Specifically, the full cell can reach a specific capacity of 151 and 107 mA h (g anode)-1 at C/6 and 3C, respectively. Moreover, this hybrid battery can achieve a high power density and an energy density of 650 W kg-1 at 15.6 W h kg-1 and 81.5 W h kg-1 at 13.6 W kg-1, respectively, outperforming most aqueous LIBs reported in the literature. This innovative strategy provides a pathway to incorporate pseudocapacitive electrodes for improving aqueous lithium-ion storage systems, enabling safe operation of large-scale energy storage without compromising their electrochemical performance.

High-pressure studies of size dependent yield strength in rhenium diboride nanocrystals.

The superhard ReB2 system is the hardest pure phase diboride synthesized to date. Previously, we have demonstrated the synthesis of nano-ReB2 and the use of this nanostructured material for texture analysis using high-pressure radial diffraction. Here, we investigate the size dependence of hardness in the nano-ReB2 system using nanocrystalline ReB2 with a range of grain sizes (20-60 nm). Using high-pressure X-ray diffraction, we characterize the mechanical properties of these materials, including bulk modulus, lattice strain, yield strength, and texture. In agreement with the Hall-Petch effect, the yield strength increases with decreasing size, with the 20 nm ReB2 exhibiting a significantly higher yield strength than any of the larger grained materials or bulk ReB2. Texture analysis on the high pressure diffraction data shows a maximum along the [0001] direction, which indicates that plastic deformation is primarily controlled by the basal slip system. At the highest pressure (55 GPa), the 20 nm ReB2 shows suppression of other slip systems observed in larger ReB2 samples, in agreement with its high yield strength. This behavior, likely arises from an increased grain boundary concentration in the smaller nanoparticles. Overall, these results highlight that even superhard materials can be made more mechanically robust using nanoscale grain size effects.

Reprecipitation: A Rapid Synthesis of Micro-Sized Silicon-Graphene Composites for Long-lasting Lithium-Ion Batteries.

Silicon microparticles (SiMPs) have gained significant attention as a lithium-ion battery anode material due to their 10 times higher theoretical capacity compared to conventional graphite anodes as well as their much lower production cost than silicon nanoparticles (SiNPs). However, SiMPs have suffered from poorer cycle life relative to SiNPs because their larger size makes them more susceptible to volume changes during charging and discharging. Creating a wrapping structure in which SiMPs are enveloped by carbon layers has proven to be an effective strategy to significantly improve the cycling performance of SiMPs. However, the synthesis processes are complex and time-/energy-consuming and therefore not scalable. In this study, a wrapping structure is created by using a simple, rapid, and scalable "modified reprecipitation method". Graphene oxide (GO) and SiMP dispersion in tetrahydrofuran is injected into n-hexane, in which GO and SiMP by themselves cannot disperse. GO and SiMP therefore aggregate and precipitate immediately after injection to form a wrapping structure. The resulting SiMP/GO film is laser scribed to reduce GO to a laser-scribed graphene (LSG). Simultaneously, SiOx and SiC protection layers form on the SiMPs through the laser process, which alleviates severe volume change. Owing to these desirable characteristics, the modified reprecipitation method successfully doubles the cycle life of SiMP/graphene composites compared to the simple physically mixing method (50.2% vs. 24.0% retention at the 100th cycle). The modified reprecipitation method opens a new synthetic strategy for SiMP/carbon composites.

A Rapid, Scalable Laser-Scribing Process to Prepare Si/Graphene Composites for Lithium-Ion Batteries.

Silicon has gained significant attention as a lithium-ion battery anode material due to its high theoretical capacity compared to conventional graphite. Unfortunately, silicon anodes suffer from poor cycling performance caused by their extreme volume change during lithiation and de-lithiation. Compositing silicon particles with 2D carbon materials, such as graphene, can help mitigate this problem. However, an unaddressed challenge remains: a simple, inexpensive synthesis of Si/graphene composites. Here, a one-step laser-scribing method is proposed as a straightforward, rapid (≈3 min), scalable, and less-energy-consuming (≈5 W for a few minutes under air) process to prepare Si/laser-scribed graphene (LSG) composites. In this research, two types of Si particles, Si nanoparticles (SiNPs) and Si microparticles (SiMPs), are used. The rate performance is improved after laser scribing: SiNP/LSG retains 827.6 mAh g-1 at 2.0 A gSi+C -1 , while SiNP/GO (before laser scribing) retains only 463.8 mAh g-1 . This can be attributed to the fast ion transport within the well-exfoliated 3D graphene network formed by laser scribing. The cyclability is also improved: SiNP/LSG retains 88.3% capacity after 100 cycles at 2.0 A gSi+C -1 , while SiNP/GO retains only 57.0%. The same trend is found for SiMPs: the SiMP/LSG shows better rate and cycling performance than SiMP/GO composites.

On the Disproportionate Contribution of Membrane Electron Donor Functionality in Membrane Biofouling.

This study set out to uncover which interfacial properties have the greatest impact on membrane organic fouling, biofouling, and fouling resistance. A relatively simple manipulation of the basic equations used in determining Lifshitz-van der Waals (LW) and Lewis acid-base (AB) surface tensions for solid materials reveals that the high electron accepticity of water makes the electron donicity of membrane and biofouling materials the key component governing their interfacial free energy of adhesion (ΔG132), which defines the favorability (or unfavorability) of one material (1) adhering to another (2) when immersed in a liquid (3). Various biofoulant and membrane LW and AB surface tensions were systematically characterized. Static bacterial adhesion, alginic acid filtration, and wastewater filtration tests were conducted to determine the fouling propensities of three different polymeric membrane materials. Experimental results of microbial adhesion, alginate fouling, and biofouling tests all correlated well with membrane electron density, where higher electron density produced less organic fouling or biofouling. These combined theoretical and experimental results confirm the importance of surface electron donicity in determining the fouling propensity of polymeric membranes.

Dynamic configurations of metallic atoms in the liquid state for selective propylene synthesis.

The use of liquid gallium as a solvent for catalytic reactions has enabled access to well-dispersed metal atoms configurations, leading to unique catalytic phenomena, including activation of neighbouring liquid atoms and mobility-induced activity enhancement. To gain mechanistic insights into liquid metal catalysts, here we introduce a GaSn0.029Ni0.023 liquid alloy for selective propylene synthesis from decane. Owing to their mobility, dispersed atoms in a Ga matrix generate configurations where interfacial Sn and Ni atoms allow for critical alignments of reactants and intermediates. Computational modelling, corroborated by experimental analyses, suggests a particular reaction mechanism by which Sn protrudes from the interface and an adjacent Ni, below the interfacial layer, aligns precisely with a decane molecule, facilitating propylene production. We then apply this reaction pathway to canola oil, attaining a propylene selectivity of ~94.5%. Our results offer a mechanistic interpretation of liquid metal catalysts with an eye to potential practical applications of this technology.

Understanding the Degradation Mechanisms of Conducting Polymer Supercapacitors.

Conducting polymers like polyaniline (PANI) are promising pseudocapacitive electrode materials, yet experience instability in cycling performance. Since polymers often degrade into oligomers, short chain length anilines have been developed to improve the cycling stability of PANI-based supercapacitors. However, the capacitance degradation mechanisms of aniline oligomer-based materials have not been systematically investigated and are little understood. Herein, two composite electrodes based on aniline trimers (AT) and carbon nanotubes (CNTs) are studied as model systems and evaluated at both pre-cycling and post-cycling states through physicochemical and electrochemical characterizations. The favorable effect of covalent bonding between AT and CNTs is confirmed to enhance cycling stability by preventing the detachment of aniline trimer and preserving the electrode microstructure throughout the charge/discharge cycling process. In addition, higher porosity has a positive effect on electron/ion transfer and the adaptation to volumetric changes, resulting in higher conductivity and extended cycle life. This work provides insights into the mechanism of enhanced cycling stability of aniline oligomers, indicating design features for aniline oligomer electrode materials to improve their electrochemical performance.

Labile Coordination Interphase for Regulating Lean Ion Dynamics in Reversible Zn Batteries.

Rechargeability in zinc (Zn) batteries is limited by anode irreversibility. The practical lean electrolytes exacerbate the issue, compromising the cost benefits of zinc batteries for large-scale energy storage. In this study, a zinc-coordinated interphase is developed to avoid chemical corrosion and stabilize zinc anodes. The interphase promotes Zn2+ ions to selectively bind with histidine and carboxylate ligands, creating a coordination environment with high affinity and fast diffusion due to thermodynamic stability and kinetic lability. Experiments and simulations indicate that interphase regulates dendrite-free electrodeposition and reduces side reactions. Implementing such labile coordination interphase results in increased cycling at 20 mA cm-2 and high reversibility of dendrite-free zinc plating/stripping for over 200 hours. A Zn||LiMn2 O4 cell with 74.7 mWh g-1 energy density and 99.7% Coulombic efficiency after 500 cycles realized enhanced reversibility using the labile coordination interphase. A lean-electrolyte full cell using only 10 µL mAh-1 electrolyte is also demonstrated with an elongated lifespan of 100 cycles, five times longer than bare Zn anodes. The cell offers a higher energy density than most existing aqueous batteries. This study presents a proof-of-concept design for low-electrolyte, high-energy-density batteries by modulating coordination interphases on Zn anodes.

A simple route to functionalized porous carbon foams from carbon nanodots for metal-free pseudocapacitors.

The development of potent pseudocapacitive charge storage materials has emerged as an effective solution for closing the gap between high-energy density batteries and high-power density and long-lasting electrical double-layer capacitors. Sulfonyl compounds are ideal candidates owing to their rapid and reversible redox reactions. However, structural instability and low electrical conductivity hinder their practical application as electrode materials. This work addresses these challenges using a fast and clean laser process to interconnect sulfonated carbon nanodots into functionalized porous carbon frameworks. In this bottom-up approach, the resulting laser-converted three-dimensional (3D) turbostratic carbon foams serve as high-surface-area, conductive scaffolds for redox-active sulfonyl groups. This design enables efficient faradaic processes using pendant sulfonyl groups, leading to a high specific capacitance of 157.6 F g-1 due to the fast reversible redox reactions of sulfonyl moieties. Even at 20 A g-1, the capacitance remained at 78.4% due to the uniform distribution of redox-active sites on the graphitic domains. Additionally, the 3D-tsSC300 electrode showed remarkable cycling stability of >15 000 cycles. The dominant capacitive processes and kinetics were analysed using extensive electrochemical characterizations. Furthermore, we successfully used 3D-tsSC300 in flexible solid-state supercapacitors, achieving a high specific capacitance of up to 17.4 mF cm-2 and retaining 91.6% of the initial capacitance after 20 000 cycles of charge and discharge coupled with 90° bending tests. Additionally, an as-assembled flexible all-solid-state symmetric supercapacitor exhibits a high energy density of 12.6 mW h cm-3 at a high power density of 766.2 W cm-3, both normalized by the volumes of the full device, which is comparable or better than state-of-the-art commercial pseudocapacitors and hybrid capacitors. The integrated supercapacitor provides a wide potential window of 2.0 V using a serial circuit, showing great promise for metal-free energy storage devices.

Roots Fuel Cell Produces and Stores Clean Energy.

In recent years, extensive scientific efforts have been conducted to develop clean bioenergy technologies. A promising approach that has been under development for more than a hundred years is the microbial fuel cell (MFC) which utilizes exoelectrogenic bacteria as an electron source in a bioelectrochemical cell. The viability of bacteria in soil MFCs can be maintained by integrating plant roots, which release organic materials that feed the bacteria. In this work, we show that rather than organic compounds, roots also release redox species that can produce electricity in a biofuel cell. We first studied the reduction of the electron acceptor Cytochrome C by green onion roots. We integrate green onion roots into a biofuel cell to produce a continuous bias-free electric current for more than 24 h in the dark. This current is enhanced upon irradiation of the onion's leaves with light. We apply cyclic voltammetry and 2D-fluorescence measurements to show that NADH and NADPH act as major electron mediators between the roots and the anode, while their concentrations in the external root matrix are increased upon irradiation of the leaves. Finally, we show that roots can contribute to energy storage by charging a supercapacitor.

Mammalian Fuel Cells Produce Electric Current.

The increasing concern about climate change has led scientists around the world to develop clean energy technologies that may replace the traditional use of fossil fuels. A promising approach is the utilization of unicellular organisms as electron donors in bio-fuel cells. To date, this method has been limited to microorganisms such as bacteria, yeast, and microalgae. In this work, we show for the first time the concept of using mammalian cell cultures and organoids as electron donors in biofuel cells. We apply cyclic voltammetry to show that upon association of ARPE19 cells with the anode, they release reducing molecules to produce electricity. Furthermore, we apply 2D-fluorescence measurements and show that upon illumination, photosensitive stem cell-derived retinal organoids, which consist of rod photoreceptors and interneurons, secrete NADH and NADPH molecules that can donate electrons at the anode to produce photocurrent.

Tailoring Metal-Organic Frameworks and Derived Materials for High-Performance Zinc-Air and Alkaline Batteries.

Developing multifunctional materials from earth-abundant elements is urgently needed to satisfy the demand for sustainable energy. Herein, we demonstrate a facile approach for the preparation of a metal-organic framework (MOF)-derived Fe2O3/C, composited with N-doped reduced graphene oxide (MO-rGO). MO-rGO exhibits excellent bifunctional electrocatalytic activities toward the oxygen evolution reaction (ηj=10 = 273 mV) and the oxygen reduction reaction (half-wave potential = 0.77 V vs reversible hydrogen electrode) with a low ΔEOER-ORR of 0.88 V in alkaline solutions. A Zn-air battery based on the MO-rGO cathode displays a high specific energy of over 903 W h kgZn-1 (∼290 mW h cm-2), an excellent power density of 148 mW cm-2, and an open-circuit voltage of 1.430 V, outperforming the benchmark Pt/C + RuO2 catalyst. We also hydrothermally synthesized a Ni-MOF that was partially transformed into a Ni-Co-layered double hydroxide (MOF-LDH). A MO-rGO||MOF-LDH alkaline battery exhibits a specific energy of 42.6 W h kgtotal mass-1 (106.5 µW h cm-2) and an outstanding specific power of 9.8 kW kgtotal mass-1 (24.5 mW cm-2). This work demonstrates the potential of MOFs and MOF-derived compounds for designing innovative multifunctional materials for catalysis, electrochemical energy storage, and beyond.

Molecular Engineering of Hierarchical Conducting Polymer Composites for Highly Stable Supercapacitors.

Long cycle life and high energy/power density are imperative to energy storage systems. Polyaniline (PANI) has shown great potential as an electrode material but is limited by poor cycling and rate performance. We present a molecular design approach of binding short-chain aniline trimers (ATs) and carbon nanotubes (CNTs) through the formation of amide covalent linkages enabled by a simple laser scribing technique. The covalently coupled AT/CNT (cc-AT/CNT) composite retains 80% of its original capacitance after 20 000 charge/discharge cycles, which readily outperforms long-chain PANI/CNT composites without covalent connections. The compact AT/CNT heterointerfaces produce fast charge/discharge kinetics and excellent rate capability. The flexible symmetric quasi-solid-state devices can be stably cycled beyond 50 000 cycles, at least 5 times longer than most PANI/CNT-based symmetric supercapacitors reported to date. This molecular design of durable conducting polymer-based electrode materials enabled by laser irradiation presents a feasible approach toward robust advanced energy storage devices.

Phase-Dependent Energy Storage Performance of the NixSey Polymorphs for Supercapacitor-Battery Hybrid Devices.

Transition-metal chalcogenides have emerged as a promising class of materials for energy storage applications due to their earth abundance, high theoretical capacity, and high electrical conductivity. Herein, we introduce a facile and one-pot electrodeposition method to prepare high-performance nickel selenide NixSey (0.5 ≤ x/y ≤ 1.5) nanostructures (specific capacity = 180.3 mA h g-1 at 1 A g-1). The as-synthesized nickel selenide (NS) nanostructure is however converted to other polymorphs of nickel selenide including orthorhombic NiSe2, trigonal Ni3Se2, hexagonal NiSe, and orthorhombic Ni6Se5 over cycling. Interestingly, NiSe2 and Ni3Se2 polymorphs that display a more metallic character and superior energy storage performance are the predominant phases after a few hundred cycles. We fabricated a hybrid device using activated carbon (AC) as a supercapacitor-type negative electrode and NS as a high-rate battery-type positive electrode (AC||NS). This hybrid device provides a high specific energy of 71 W h kg-1, an excellent specific power of up to 31 400 W kg-1, and exceptional cycling stability (80% retention of the initial capacity after 20 000 cycles). The higher energy storage performance of the device is a result of the development of high-performance NiSe2 and Ni3Se2 polymorphs. Moreover, the reduction of the critical dimension of the NS particles to the nanoscale partially induces an extrinsic pseudocapacitive behavior that improves the rate capability and durability of the device. We also explored the origin of the superior energy storage performance of the NS polymorphs using density functional theory calculations in terms of the computed density of states around the Fermi level, electrical conductivity, and quantum capacitance that follows the trend NiSe2 > Ni3Se2 > NiSe > Ni6Se5. The present study thus provides an appealing approach for tailoring the phase composition of NS as an alternative to the commonly used templated synthesis methods.

A 3D-Printed, Freestanding Carbon Lattice for Sodium Ion Batteries.

Increasing mass loadings of battery electrodes critically enhances the energy density of an overall battery by eliminating much of the inactive components, while compacting the battery size and lowering the costs of the ingredients. A hard carbon microlattice, digitally designed and fabricated by stereolithography 3D-printing and pyrolysis, offers enormous potential for high-mass-loading electrodes. In this work, sodium-ion batteries using hard carbon microlattices produced by an inexpensive 3D printer are demonstrated. Controlled periodic carbon microlattices are created with enhanced ion transport through microchannels. Carbon microlattices with a beam width of 32.8 µm reach a record-high areal capacity of 21.3 mAh cm-2 at a loading of 98 mg cm-2 without degrading performance, which is much higher than the conventional monolithic electrodes (≈5.2 mAh cm-2 at 92 mg cm-2 ). Furthermore, binder-free, pure-carbon elements of microlattices enable the tracking of structural changes in hard carbon that support the hypothesized intercalation of ions at plateau regions by temporal ex situ X-ray diffraction measurements. These results will advance the development of high-performance and low-cost anodes for sodium-ion batteries as well as help with understanding the mechanisms of ion intercalations in hard carbon, expanding the utilities of 3D-printed carbon architectures in both applications and fundamental studies.

Low-temperature liquid platinum catalyst.

Insights into metal-matrix interactions in atomically dispersed catalytic systems are necessary to exploit the true catalytic activity of isolated metal atoms. Distinct from catalytic atoms spatially separated but immobile in a solid matrix, here we demonstrate that a trace amount of platinum naturally dissolved in liquid gallium can drive a range of catalytic reactions with enhanced kinetics at low temperature (318 to 343 K). Molecular simulations provide evidence that the platinum atoms remain in a liquid state in the gallium matrix without atomic segregation and activate the surrounding gallium atoms for catalysis. When used for electrochemical methanol oxidation, the surface platinum atoms in the gallium-platinum system exhibit an activity of [Formula: see text] three orders of magnitude higher than existing solid platinum catalysts. Such a liquid catalyst system, with a dynamic interface, sets a foundation for future exploration of high-throughput catalysis.

Low Temperature Nano Mechano-electrocatalytic CH4 Conversion.

Transforming natural resources to energy sources, such as converting CH4 to H2 and carbon, at high efficiency and low cost is crucial for many industries and environmental sustainability. The high temperature requirement of CH4 conversion regarding many of the current methods remains a critical bottleneck for their practical uptake. Here we report an approach based on gallium (Ga) liquid metal droplets, Ni(OH)2 cocatalysts, and mechanical energy input that offers low-temperature and scalable CH4 conversion into H2 and carbon. Mainly driven by the triboelectric voltage, originating from the joint contributions of the cocatalysts during agitation, CH4 is converted at the Ga and Ni(OH)2 interface through nanotribo-electrochemical reaction pathways. The efficiency of the system is enhanced when the reaction is performed at an increased pressure. The dehydrogenation of other nongaseous hydrocarbons using this approach is also demonstrated. This technology presents a possible low energy route for CH4 conversion without involving high temperature and harsh operating conditions.