Extreme Environmental Thermal Shock Induced Dislocation-Rich Pt Nanoparticles Boosting Hydrogen Evolution Reaction

WS2 Moiré Superlattices Supporting Au Nanoclusters and Isolated Ru to Boost Hydrogen Production

Maximizing the catalytic activity of single-atom and nanocluster catalysts through the modulation of the interaction between these components and the corresponding supports is crucial but challenging. Herein, guided by theoretical calculations, a nanoporous bilayer WS2 Moiré superlattices (MSLs) supported Au nanoclusters (NCs) adjacent to Ru single atoms (SAs) (Ru1/Aun-2LWS2) is developed for alkaline hydrogen evolution reaction (HER) for the first time. Theoretical analysis suggests that the induced robust electronic metal-support interaction effect in Ru1/Aun-2LWS2 is prone to promote the charge redistribution among Ru SAs, Au NCs, and WS2 MSLs support, which is beneficial to reduce the energy barrier for water adsorption and thus promoting the subsequent H2 formation. As feedback, the well-designed Ru1/Aun-2LWS2 electrocatalyst exhibits outstanding HER performance with high activity (η10 = 19 mV), low Tafel slope (35 mV dec-1), and excellent long-term stability. Further, in situ, experimental studies reveal that the reconstruction of Ru SAs/NCs with S vacancies in Ru1/Aun-2LWS2 structure acts as the main catalytically active center, while high-valence Au NCs are responsible for activating and stabilizing Ru sites to prevent the dissolution and deactivation of active sites. This work offers guidelines for the rational design of high-performance atomic-scale electrocatalysts.

Cathode-Electrolyte Interphase Engineering toward Fast-Charging LiFePO4 Cathodes by Flash Carbon Coating

Lithium iron phosphate (LiFePO4, LFP) batteries are widely used in electric vehicles and energy storage systems due to their excellent cycling stability, affordability and safety. However, the rate performance of LFP remains limited due to its low intrinsic electronic and ionic conductivities. In this work, an ex situ flash carbon coating method is developed to enhance the interfacial properties for fast charging. A continuous, amorphous carbon layer is achieved by rapidly decomposing the precursors and depositing carbon species in a confined space within 10 s. Simultaneously, different heteroatoms can be introduced into the surface carbon matrix, which regulates the irregular growth of cathode-electrolyte interphase (CEI) and selectively facilitates the inorganic region formation. The inorganic-rich, hybrid conductive CEI not only promotes electron and ion transport but also restricts parasitic side reactions. Consequently, LFP cathodes with fluorinated carbon coatings exhibited the highest capacity of 151 mAh g-1 at 0.2 C and 96 mAh g-1 at 10 C, indicating their excellent rate capability over commercial LFP (58 mAh g-1 at 10 C). This solvent-free, versatile surface modification is shown for other electrode materials, providing an efficient platform for electrode-electrolyte interphase engineering through a surface post-treatment.

Coupling Antisite Defect and Lattice Tensile Stimulates Facile Isotropic Li-Ion Diffusion

Despite widely used as a commercial cathode, the anisotropic 1D channel hopping of lithium ions along the [010] direction in LiFePO4 prevents its application in fast charging conditions. Herein, an ultrafast nonequilibrium high-temperature shock technology is employed to controllably introduce the Li-Fe antisite defects and tensile strain into the lattice of LiFePO4. This design makes the study of the effect of the strain field on the performance further extended from the theoretical calculation to the experimental perspective. The existence of Li-Fe antisite defects makes it feasible for Li+ to move from the 4a site of the edge-sharing octahedra across the ab plane to 4c site of corner-sharing octahedra, producing a new diffusion channel different from [010]. Meanwhile, the presence of a tensile strain field reduces the energy barrier of the new 2D diffusion path. In the combination of electrochemical experiments and first-principles calculations, the unique multiscale coupling structure of Li-Fe antisite defects and lattice strain promotes isotropic 2D interchannel Li+ hopping, leading to excellent fast charging performance and cycling stability (high-capacity retention of 84.4% after 2000 cycles at 10 C). The new mechanism of Li+ diffusion kinetics accelerated by multiscale coupling can guide the design of high-rate electrodes.

Thermal Shock Synthesis for Loading Sub-2 nm Ru Nanoclusters on Titanium Nitride as a Remarkable Electrocatalyst toward Hydrogen Evolution Reaction

Heterogeneous catalysts embracing metal entities on suitable supports are profound in catalyzing various chemical reactions, and substantial synthetic endeavors in metal-support interaction modulation are made to enhance catalytic performance. Here, it is reported the loading of sub-2 nm Ru nanocrystals (NCs) on titanium nitride support (HTS-Ru-NCs/TiN) via a special Ru-Ti interaction using the high-temperature shock (HTS) method. Direct dechlorination of the adsorbed RuCl3, ultrafast nucleation process, and short coalescence duration at ultrahigh temperatures contribute to the immobilization of Ru NCs on TiN support via producing the Ru-Ti interfacial perimeter. HTS-Ru-NCs/TiN shows remarkable activity toward hydrogen evolution reaction (HER) in alkaline solution, yielding ultralow overpotentials of 16.3 and 86.6 mV to achieve 10 and 100 mA cm-2, respectively. The alkaline and anion exchange membrane water electrolyzers assembled using HTS-Ru-NCs/TiN yield 1.0 A cm-2 at 1.65 and 1.67 V, respectively, which validate its applicability in the hydrogen production industry. Theoretical simulations reveal the favorable formation of Ru─O and Ti─H bonds at the interfacial perimeters between Ru NCs and TiN, which accelerates the prerequisite water dissociation kinetics for enhanced HER activity. This exemplified work motivates the design of specific interfacial perimeters via the HTS strategy to improve the performance of diverse catalysis.

Approaching Ultimate Synthesis Reaction Rate of Ni-Rich Layered Cathodes for Lithium-Ion Batteries

Nickel-rich layered oxide LiNixCoyMnzO2 (NCM, x + y + z = 1) is the most promising cathode material for high-energy lithium-ion batteries. However, conventional synthesis methods are limited by the slow heating rate, sluggish reaction dynamics, high energy consumption, and long reaction time. To overcome these challenges, we first employed a high-temperature shock (HTS) strategy for fast synthesis of the NCM, and the approaching ultimate reaction rate of solid phase transition is deeply investigated for the first time. In the HTS process, ultrafast average reaction rate of phase transition from Ni0.6Co0.2Mn0.2(OH)2 to Li- containing oxides is 66.7 (% s-1), that is, taking only 1.5 s. An ultrahigh heating rate leads to fast reaction kinetics, which induces the rapid phase transition of NCM cathodes. The HTS-synthesized nickel-rich layered oxides perform good cycling performances (94% for NCM523, 94% for NCM622, and 80% for NCM811 after 200 cycles at 4.3 V). These findings might also assist to pave the way for preparing effectively Ni-rich layered oxides for lithium-ion batteries.

Pt Single-Atoms on Structurally-Integrated 3D N-Doped Carbon Tubes Grid for Ampere-Level Current Density Hydrogen Evolution

To date, the excellent mass-catalytic activities of Pt single-atoms catalysts (Pt-SACs) toward hydrogen evolution reaction (HER) are categorically confirmed; however, their high current density performance remains a challenge for practical applications. Here, a binder-free approach is exemplified to fabricate self-standing superhydrophilic-superaerphobic Pt-SACs cathodes by directly anchoring Pt-SAs via Pt-NxC4-x coordination bonds to the structurally-integrated 3D nitrogen-doped carbon tubes (N-CTs) array grid (denoted as Pt@N-CTs). The 3D Pt@N-CTs cathode with optimal Pt-SACs loading is capable of operating at a high current density of 1000 mA cm-2 with an ultralow overpotential of 157.9 mV with remarkable long-term stability over 11 days at 500 mA cm-2. The 3D super-wettable free-standing Pt@N-CTs possess interconnected vertical and lateral N-CTs with hierarchical-sized open channels, which facilitates the mass transfer. The binder-free immobilization adding to the large surface area and 3D-interconnected open channels endow Pt@N-CTs cathodes with high accessible active sites, electrical conductivity, and structural stability that maximize the utilization efficiency of Pt-SAs to achieve ampere-level current density HER at low overpotentials.

Platinum Nanoparticles Bonded with Carbon Nanotubes for High-Performance Ampere-Level All-Water Splitting

Platinum nanoparticles loaded on a nitrogen-doped carbon nanotubes exhibit a brilliant hydrogen evolution reaction (HER) in an alkaline solution, but their bifunctional hydrogen and oxygen evolution reaction (OER) has not been reported due to the lack of a strong Pt-C bond. In this work, platinum nanoparticles bonded in carbon nanotubes (Pt-NPs-bonded@CNT) with strong Pt-C bonds are designed toward ultralow overpotential water splitting ability in alkaline solution. Benefit from the strong interaction between platinum and high conductivity carbon nanotube substrates through the Pt-C bond also the platinum nanoparticles bonded in carbon nanotube can provide more stable active sites, as a result, the Pt-NPs-bonded@CNT exhibits excellent hydrogen evolution in acid and alkaline solution with ultralow overpotential of 0.19 and 0.23 V to reach 1000 mA cm-2, respectively. Besides, it shows superior oxygen evolution electrocatalysis in alkaline solution with a low overpotential of 1.69 V at 1000 mA cm-2. Furthermore, it also exhibits high stability over 110 h against the evolution of oxygen and hydrogen at 1000 mA cm-2. This strategy paves the way to the high performance of bifunctional electrocatalytic reaction with extraordinary stability originating from optimized electron density of metal active sites due to strong metal-substrate interaction.

Continuous and low-carbon production of biomass flash graphene

Flash Joule heating (FJH) is an emerging and profitable technology for converting inexhaustible biomass into flash graphene (FG). However, it is challenging to produce biomass FG continuously due to the lack of an integrated device. Furthermore, the high-carbon footprint induced by both excessive energy allocation for massive pyrolytic volatiles release and carbon black utilization in alternating current-FJH (AC-FJH) reaction exacerbates this challenge. Here, we create an integrated automatic system with energy requirement-oriented allocation to achieve continuous biomass FG production with a much lower carbon footprint. The programmable logic controller flexibly coordinated the FJH modular components to realize the turnover of biomass FG production. Furthermore, we propose pyrolysis-FJH nexus to achieve biomass FG production. Initially, we utilize pyrolysis to release biomass pyrolytic volatiles, and subsequently carry out the FJH reaction to focus on optimizing the FG structure. Importantly, biochar with appropriate resistance is self-sufficient to initiate the FJH reaction. Accordingly, the medium-temperature biochar-based FG production without carbon black utilization exhibited low carbon emission (1.9 g CO2-eq g-1 graphene), equivalent to a reduction of up to ~86.1% compared to biomass-based FG production. Undoubtedly, this integrated automatic system assisted by pyrolysis-FJH nexus can facilitate biomass FG into a broad spectrum of applications.

Kinetically Controlled Synthesis of Metallic Glass Nanoparticles with Expanded Composition Space

Nanoscale metallic glasses offer opportunities for investigating fundamental properties of amorphous solids and technological applications in biomedicine, microengineering, and catalysis. However, their top-down fabrication is limited by bulk counterpart availability, and bottom-up synthesis remains underexplored due to strict formation conditions. Here, a kinetically controlled flash carbothermic reaction is developed, featuring ultrafast heating (>105 K s-1) and cooling rates (>104 K s-1), for synthesizing metallic glass nanoparticles within milliseconds. Nine compositional permutations of noble metals, base metals, and metalloid (M1─M2─P, M1 = Pt/Pd, M2 = Cu/Ni/Fe/Co/Sn) are synthesized with widely tunable particle sizes and substrates. Through combinatorial development, a substantially expanded composition space for nanoscale metallic glass is discovered compared to bulk counterpart, revealing that the nanosize effect enhances glass forming ability. Leveraging this, several nanoscale metallic glasses are synthesized with composition that have never, to the knowledge, been synthesized in bulk. The metallic glass nanoparticles exhibit high activity in heterogeneous catalysis, outperforming crystalline metal alloy nanoparticles.

Ultrafast micro/nano-manufacturing of metastable materials for energy

The structural engineering of metastable nanomaterials with abundant defects has attracted much attention in energy-related fields. The high-temperature shock (HTS) technique, as a rapidly developing and advanced synthesis strategy, offers significant potential for the rational design and fabrication of high-quality nanocatalysts in an ultrafast, scalable, controllable and eco-friendly way. In this review, we provide an overview of various metastable micro- and nanomaterials synthesized via HTS, including single metallic and bimetallic nanostructures, high entropy alloys, metal compounds (e.g. metal oxides) and carbon nanomaterials. Note that HTS provides a new research dimension for nanostructures, i.e. kinetic modulation. Furthermore, we summarize the application of HTS-as supporting films for transmission electron microscopy grids-in the structural engineering of 2D materials, which is vital for the direct imaging of metastable materials. Finally, we discuss the potential future applications of high-throughput and liquid-phase HTS strategies for non-equilibrium micro/nano-manufacturing beyond energy-related fields. It is believed that this emerging research field will bring new opportunities to the development of nanoscience and nanotechnology in both fundamental and practical aspects.

Transforming Nature's Bath Sponge into Stacking Faults-Enhanced Ag Nanorings-Decorated Catalyst for Hydrogen Evolution Reaction

The rational design of cost-effective and efficient electrocatalysts for electrochemical water splitting is essential for green hydrogen production. Utilizing nanocatalysts with abundant active sites, high surface area, and deliberate stacking faults is a promising approach for enhancing catalytic efficiency. In this study, we report a simple strategy to synthesize a highly efficient electrocatalyst for the hydrogen evolution reaction (HER) using carbonized luffa cylindrica as a conductive N-doped carbon skeleton decorated with Ag nanorings that are activated by introducing stacking faults. The introduction of stacking faults and the resulting tensile strain into the Ag nanorings results in a significant decrease in the HER overpotential, enabling the use of Ag as an efficient HER electrocatalyst. Our findings demonstrate that manipulating the crystal properties of electrocatalysts, even for materials with intrinsically poor catalytic activity such as Ag, can result in highly efficient catalysts. Further, applying a conductive carbon backbone can lower the quantities of metal needed without compromising the HER activity. This approach opens up new avenues for designing high-performance electrocatalysts with very low metallic content, which could significantly impact the development of sustainable and cost-effective electrochemical water-splitting systems.

Strain and Shell Thickness Engineering in Pd3 Pb@Pt Bifunctional Electrocatalyst for Ethanol Upgrading Coupled with Hydrogen Production

The ethanol oxidation reaction (EOR) is an attractive alternative to the sluggish oxygen evolution reaction in electrochemical hydrogen evolution cells. However, the development of high-performance bifunctional electrocatalysts for both EOR and hydrogen evolution reaction (HER) is a major challenge. Herein, the synthesis of Pd3 Pb@Pt core-shell nanocubes with controlled shell thickness by Pt-seeded epitaxial growth on intermetallic Pd3 Pb cores is reported. The lattice mismatch between the Pd3 Pb core and the Pt shell leads to the expansion of the Pt lattice. The synergistic effects between the tensile strain and the core-shell structures result in excellent electrocatalytic performance of Pd3 Pb@Pt catalysts for both EOR and HER. In particular, Pd3 Pb@Pt with three Pt atomic layers shows a mass activity of 8.60 A mg-1 Pd+Pt for ethanol upgrading to acetic acid and close to 100% of Faradic efficiency for HER. An EOR/HER electrolysis system is assembled using Pd3 Pb@Pt for both the anode and cathode, and it is shown that low cell voltage of 0.75 V is required to reach a current density of 10 mA cm-2 . The present work offers a promising strategy for the development of bifunctional catalysts for hybrid electrocatalytic reactions and beyond.

Copious Dislocations Defect in Amorphous/Crystalline/Amorphous Sandwiched Structure P-NiMoO4 Electrocatalyst toward Enhanced Hydrogen Evolution Reaction

The design and synthesis of efficient, inexpensive, and long-term stable heterostructured electrocatalysts with high-density dislocations for hydrogen evolution reaction in alkaline media and seawater are still a great challenge. An amorphous/crystalline/amorphous sandwiched structure with abundant dislocations were synthesized through thermal phosphidation strategies. The dislocations play an important role in the hydrogen evolution reactions. Copious dislocation defects, combined with cracks, and the synergistic interfacial effect between crystalline phase and amorphous phase regulate the electronic structure of electrocatalyst, provide more active sites, and thus endow the electrocatalysts with excellent catalytic activity under alkaline water and seawater. The overpotentials of P-NiMoO4 at 10 mA/cm2 in 1 M KOH aqueous solution and seawater are 45 and 75 mV, respectively. Additionally, the P-NiMoO4 electrocatalyst exhibits long-term stability over 100 h. This study provides a simple approach for synthesizing amorphous/crystalline/amorphous sandwiched non-noble-metal electrocatalysts with abundant dislocations for hydrogen evolution reaction.

Frank Partial Dislocations in Coplanar Ir/C Ultrathin Nanosheets Boost Hydrogen Evolution Reaction

Developing highly active and stable acidic hydrogen evolution catalysts is of great significance and challenge for the long-term operation of commercial proton exchange membrane (PEM) electrolyzers. In this work, coplanar ultrathin nanosheets composed of rich-Frank partial dislocations (FPDs) are first synthesized. Ir nanoparticles and carbon (Dr-Ir/C NSs) use a nonequilibrium high-temperature thermal shock method (>1200 °C) and KBr template-assisted techniques. Dr-Ir/C NSs exhibit excellent hydrogen evolution reaction (HER) performance with a remarkably high mass activity of 6.64 A mg-1 at 50 mV, which is among the best Ir-based catalysts.In addition, Dr-Ir/C NSs are able to operate stably at 1.0 A cm-2 for 200 h as a cathode in a PEM electrolyser, and the original coplanar ultrathin nanosheets structure are maintained after the test, demonstrating excellent stability against stacking and agglomeration. Geometrical phase analysis and theoretical calculations show that the FPDs produce a 4% compressive strain in the Dr-Ir/C NSs, and the compressive strain weaken the adsorption of H* by Ir, thus increasing the intrinsic activity of the catalyst.

Microwave Phosphine-Plasma-Assisted Ultrafast Synthesis of Halogen-Doped Ru/RuP2 with Surface Intermediate Adsorption Modulation for Efficient Alkaline Hydrogen Evolution Reaction

Anionic modification engineering is a crucial approach to develop highly efficient electrocatalysts for hydrogen evolution reaction. Herein, halogen elements (X = Cl, Br, and I)-modified Ru-based nanosheets (X-Ru/RuP2 ) are designed by rapid and eco-friendly microwave-phosphide plasma approach within 60 s. Experimental and density functional theory calculations verify that the introduced halogen element, especially Br, can optimize the surface intermediates adsorption. Specially, the designed Br-Ru/RuP2 favors the water dissociation and following hydrogen adsorption/desorption process. Then, the as-synthesized Br-Ru/RuP2 exhibits low overpotential of 34 mV to reach 10 mA cm-2 coupled with small Tafel slope of 27 mV dec-1 in alkaline electrolyte with excellent long-term stability. Moreover, the electrocatalytic performances in acid and neutral media are also boosted via Br element modification. This work paves a novel way to regulate the electronic structure of Ru-based compounds, and then can boost the electrocatalytic kinetics.

High-entropy alloys in electrocatalysis: from fundamentals to applications

High-entropy alloys (HEAs) comprising five or more elements in near-equiatomic proportions have attracted ever increasing attention for their distinctive properties, such as exceptional strength, corrosion resistance, high hardness, and excellent ductility. The presence of multiple adjacent elements in HEAs provides unique opportunities for novel and adaptable active sites. By carefully selecting the element configuration and composition, these active sites can be optimized for specific purposes. Recently, HEAs have been shown to exhibit remarkable performance in electrocatalytic reactions. Further activity improvement of HEAs is necessary to determine their active sites, investigate the interactions between constituent elements, and understand the reaction mechanisms. Accordingly, a comprehensive review is imperative to capture the advancements in this burgeoning field. In this review, we provide a detailed account of the recent advances in synthetic methods, design principles, and characterization technologies for HEA-based electrocatalysts. Moreover, we discuss the diverse applications of HEAs in electrocatalytic energy conversion reactions, including the hydrogen evolution reaction, hydrogen oxidation reaction, oxygen reduction reaction, oxygen evolution reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, and alcohol oxidation reaction. By comprehensively covering these topics, we aim to elucidate the intricacies of active sites, constituent element interactions, and reaction mechanisms associated with HEAs. Finally, we underscore the imminent challenges and emphasize the significance of both experimental and theoretical perspectives, as well as the potential applications of HEAs in catalysis. We anticipate that this review will encourage further exploration and development of HEAs in electrochemistry-related applications.

Low-cost flexible textile electrocatalyst for overall water splitting

Through the braidability of cotton fiber and the richness of surface functional groups, cotton fiber can be woven into any shape, and catalytically active centers can be stably anchored on the fibers. During the electrocatalytic overall water splitting (OWS) process, catalyst shedding and activity reduction can be effectively avoided.

Tensile Strain-Mediated Spinel Ferrites Enable Superior Oxygen Evolution Activity

Exploring efficient strategies to overcome the performance constraints of oxygen evolution reaction (OER) electrocatalysts is vital for electrocatalytic applications such as H2O splitting, CO2 reduction, N2 reduction, etc. Herein, tunable, wide-range strain engineering of spinel oxides, such as NiFe2O4, is proposed to enhance the OER activity. The lattice strain is regulated by interfacial thermal mismatch during the bonding process between thermally expanding NiFe2O4 nanoparticles and the nonexpanding carbon fiber substrate. The tensile lattice strain causes energy bands to flatten near the Fermi level, lowering eg orbital occupancy, effectively increasing the number of electronic states near the Fermi level, and reducing the pseudoenergy gap. Consequently, the energy barrier of the rate-determining step for strained NiFe2O4 is reduced, achieving a low overpotential of 180 mV at 10 mA/cm2. A total water decomposition voltage range of 1.52-1.56 V at 10 mA/cm2 (without iR correction) was achieved in an asymmetric alkaline electrolytic cell with strained NiFe2O4 nanoparticles, and its robust stability was verified with a voltage retention of approximately 99.4% after 100 h. Furthermore, the current work demonstrates the universality of tuning OER performance with other spinel ferrite systems, including cobalt, manganese, and zinc ferrites.

High-temperature electrothermal remediation of multi-pollutants in soil

Soil contamination is an environmental issue due to increasing anthropogenic activities. Existing processes for soil remediation suffer from long treatment time and lack generality because of different sources, occurrences, and properties of pollutants. Here, we report a high-temperature electrothermal process for rapid, water-free remediation of multiple pollutants in soil. The temperature of contaminated soil with carbon additives ramps up to 1000 to 3000 °C as needed within seconds via pulsed direct current input, enabling the vaporization of heavy metals like Cd, Hg, Pb, Co, Ni, and Cu, and graphitization of persistent organic pollutants like polycyclic aromatic hydrocarbons. The rapid treatment retains soil mineral constituents while increases infiltration rate and exchangeable nutrient supply, leading to soil fertilization and improved germination rates. We propose strategies for upscaling and field applications. Techno-economic analysis indicates the process holds the potential for being more energy-efficient and cost-effective compared to soil washing or thermal desorption.

Electronic Structure Engineering of Pt Species over Pt/WO3 toward Highly Efficient Electrocatalytic Hydrogen Evolution

Pt-based supported materials, a widely used electrocatalyst for hydrogen evolution reaction (HER), often experience unavoidable electron loss, resulting in a mismatching of electronic structure and HER behavior. Here, a Pt/WO3 catalyst consisting of Pt species strongly coupled with defective WO3 polycrystalline nanorods is rationally designed. The electronic structure engineering of Pt sites on WO3 can be systematically regulated, and so that the optimal electron-rich Pt sites on Pt/WO3 -600 present an excellent HER activity with only 8 mV overpotential at 10 mA cm-2 . Particularly, the mass activity reaches 7015 mA mg-1 at the overpotential of 50 mV, up to 26-fold higher than that of the commercial Pt/C. The combination of experimental and theoretical results demonstrates that the O vacancies of WO3 effectively mitigate the tendency of electron transfer from Pt sites to WO3 , so that the d-band center could reach an appropriate level relative to Fermi level, endowing it with a suitableΔ G H ∗ $\Delta {G_{{{\rm{H}}^ * }}}$ . This work identifies the influence of the electronic structure on catalytic activity.

Pluronic Induced Interparticle Attraction and Re-entrant Liquid-Liquid Phase Separation in Charged Silica Nanoparticle Suspensions

Tuning surface properties of nanoparticles by introducing charge, surface functionalization, or polymer grafting is central to their stability and applications. Here, we show that introducing non-DLVO forces like steric and hydrophobic effects in charged silica nanoparticle suspensions through interaction with a nonionic surfactant brings about interesting modulations in their interparticle interaction and phase behavior. The Ludox TM-40 negatively charged silica suspensions thus exhibit liquid-liquid phase separation driven by the onset of interparticle attraction in the system in the presence of the triblock copolymer Pluronic P123. The observed phase separations are thermoresponsive in nature, as they are associated with lower consolute temperatures and a re-entrant behavior as a function of temperature. The nanoparticle-Pluronic system thus undergoes transformation from one-phase to two-phase and then back to one-phase with monotonic increase in temperature. Evolution of the interparticle interaction in the composite system is investigated by dynamic light scattering (DLS), small angle neutron scattering (SANS), zeta potential, rheological, and fluorescence spectroscopy studies. Zeta potential studies show that the charge interaction in the system is partially mitigated through adsorption of a Pluronic micellar layer on the nanoparticle surfaces. Contrast-matching SANS studies suggest that hydrophobic interactions between the adsorbed micellar layer bring about the onset of interparticle attraction in the system. The results are unique and not reported hitherto in charged silica nanoparticle systems.

Bimetallic Pt-Hg Aerogels for Electrocatalytic Upgrading of Ethanol to Acetate

Electrochemical upgrading of ethanol to acetic acid provides a promising strategy to couple with the current hydrogen production from water electrolysis. This work reports the design of a series of bimetallic PtHg aerogels, where the PtHg aerogel exhibits a 10.5-times higher mass activity than that of commercial Pt/C toward ethanol oxidation. More impressively, the PtHg aerogel demonstrates nearly 100% selectivity toward the production of acetic acid. The operando infrared spectroscopic studies and nuclear magnetic resonance analysis verify the preferable C2 pathway mechanism during the reaction. This work opens an avenue for the electrochemical synthesis of acetic acid via ethanol electrolysis.

Ultra-Low Pt Doping and Pt-Ni Pair Sites in Amorphous/Crystalline Interfacial Electrocatalyst Enable Efficient Alkaline Hydrogen Evolution

Noble metal doping can achieve an increase in mass activity (MA) without sacrificing catalysis efficiency and stability, so that alkaline hydrogen evolution reaction (HER) performance of the catalyst can be optimized to the maximum degree. However, its excessively large ionic radius makes it difficult to achieve either interstitial doping or substitutional doping under mild conditions. Herein, a hierarchical nanostructured electrocatalyst with enriched amorphous/crystalline interfaces for high-efficiency alkaline HER is reported, which is composed of amorphous/crystalline (Co, Ni)₁₁ (HPO₃ )₈ (OH)₆ homogeneous hierarchical structure with an ultra-low doped Pt (Pt-a/c-NiHPi). Benefiting from the structural flexibility of the amorphous component, extremely low Pt (0.21 wt.%, totally 3.31 µg Pt on 1 cm^-2 NF) are stably doped on it via a simple two-phase hydrothermal method. The DFT calculations show that due to the strongly electron transfer between the crystalline/amorphous components at the interfaces, electrons finally concentrate toward Pt and Ni in the amorphous components, thus the electrocatalyst has near-optimal energy barriers and adsorption energy for H₂ O^* and H^* . With the above benefits, the obtained catalyst exhibits an exceptionally high MA (39.1 mA µg^-1 _Pt ) at 70 mV, which is almost the highest level among the reported Pt-based electrocatalysts for alkaline HER.

Liquid nitrogen quenching inducing lattice tensile strain to endow nitrogen/fluorine co-doping Fe3O4 nanocubes assembled on porous carbon with optimizing hydrogen evolution reaction

In this work, the lattice tensile strain of nitrogen/fluorine co-doping ferroferric oxide (Fe₃O₄) nanocubes assembled on chrysanthemum tea-derived porous carbon is induced through a novel liquid nitrogen quenching treatment (named as TS-NF-FO/PC_X-Y, TS: Tensile strain, NF: Nitrogen/Fluorine co-doping, FO: Fe₃O₄, PC: Porous carbon, X: The weight ratio of KOH/carbon, Y: The adding amount of porous carbon). Besides, the electrocatalytic activity influenced by the adding amount of porous carbon, the type of dopant, and the introduction of lattice tensile strain is systematically studied and explored. The interconnected porous carbon could improve electrical conductivity and prevent Fe₃O₄ nanocubes from aggregating. The induced nitrogen/fluorine could cause extrinsic defects and tailor the intrinsic electron state of the host materials. Lattice tensile strain could tailor the surface electronic structure of Fe₃O₄ via changing the dispersion of surface atoms and their bond lengths. Impressively, the designed TS-NF-FO/PC₅-0.25 delivers a low overpotential of 207.3 ± 0.4 mV at 10 mA/cm² and demonstrates desirable reaction dynamics. Density functional theory calculations illustrate that the electron structure and hydrogen adsorption free energy (ΔG_*H) are optimized by the synergistic effect among porous carbon, nitrogen/fluorine co-doping and lattice tensile strain, thus promoting hydrogen evolution reaction (HER) catalytic activity. Overall, this work paves the way to unravel the enhancement mechanism of HER on transition metal oxide-based materials by electronic structure and phase composition modulation strategy.

The Role of Discrepant Reactive Intermediates on Ru-Ru2 P Heterostructure for pH-Universal Hydrogen Oxidation Reaction

Developing highly efficient electrocatalysts for hydrogen oxidation reaction (HOR) under alkaline media is essential for the commercialization of alkaline exchange membrane fuel cell (AEMFC). However, the kinetics of HOR in alkaline media is complicated, resulting in orders of magnitude slower than that in acid, even for the state-of-the-art Pt/C. Here, we find that Ru-Ru₂ P/C heterostructure shows HOR performance with a non-monotonous variation in a whole pH region. Unexpectedly, an inflection point located at pH≈7 is observed, showing an anomalous behavior that HOR activity under alkaline media surpasses acidic media. Combining experimental results and theoretical calculations, we propose the roles of discrepant reactive intermediates for pH-universal HOR, while H* and H₂ O* adsorption strengths are responsible for acidic HOR, and OH* adsorption strength is essential for alkaline HOR. This work not only sheds light on fundamentally understanding the mechanism of HOR but also provides new designing principles for pH-targeted electrocatalysts.

Ultrafast Synthesis of Metal-Layered Hydroxides in a Dozen Seconds for High-Performance Aqueous Zn (Micro-) Battery

Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field. However, most of the synthetic routes at present mainly rely on traditional bottom-up method, which involves tedious steps, time-consuming treatments, or additional alkaline media, and is unfavorable for high-efficiency production. Herein, we present a facile, ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method. With high reaction kinetics caused by the instantaneous high temperature, seven kinds of transition metal-layered hydroxides (TM-LDHs) are formed on carbon cloth. Therein, the fastest synthesis rate reaches ~ 0.46 cm2 s-1. Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates. This efficient approach avoids the use of extra agents, multiple steps, and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability, showing practical advantages in both common and micro-zinc ion-based energy storage devices. To prove its utility, as a cathode in rechargeable aqueous alkaline Zn (micro-) battery, the NiCo LDH@carbon cloth exhibits a high energy density, superior to most transition metal LDH materials reported so far.

Ultrafast Non-Equilibrium Synthesis of Cathode Materials for Li-Ion Batteries

The synthesis of cathode materials plays an important role in determining the production efficiency, cost, and performance of lithium-ion batteries. However, conventional synthesis methods always experience a slow heating rate and involve a complicated multistep reaction process and sluggish reaction dynamics, leading to high energy and long time consumption. Herein, a high-temperature shock (HTS) strategy is reported for the ultrafast synthesis of cathode materials in seconds. The HTS process experiences an ultrahigh heating rate, leading to a non-equilibrium reaction and fast reaction kinetics, and avoids high energy and long time consumption. Mainstream cathode materials (such as LiMn₂ O₄ , LiCoO₂ , LiFePO₄ , and Li-rich layered oxide/NiO heterostructured material) are successfully synthesized with pure phases, oxygen vacancies, ultrasmall particle sizes, and good electrochemical performance. The HTS process not only provides an efficient synthesis approach for cathode materials, but also can be extended beyond lithium-ion batteries.

Recent advances in understanding and design of efficient hydrogen evolution electrocatalysts for water splitting: A comprehensive review

An unsustainable reliance on fossil fuels is the primary cause of the vast majority of greenhouse gas emissions, which in turn lead to climate change. Green hydrogen (H₂), which may be generated by electrolyzing water with renewable power sources, is a possible substitute for fossil fuels. On the other hand, the increasing intricacy of hydrogen evolution electrocatalysts that are presently being explored makes it more challenging to integrate catalytic theories, catalytic fabrication procedures, and characterization techniques. This review will initially present the thermodynamics, kinetics, and associated electrical and structural characteristics for HER electrocatalysts before highlighting design approaches for the electrocatalysts. Secondly, an in-depth discussion regarding the rational design, synthesis, mechanistic insight, and performance improvement of electrocatalysts is centered on both the intrinsic and extrinsic influences. Thirdly, the most recent technological advances in electrocatalytic water-splitting approaches are described. Finally, the difficulties and possibilities associated with generating extremely effective HER electrocatalysts for water-splitting applications are discussed.

Plasma synthesis of defect-rich flexible carbon cloth decorated with PtRu alloyed nanoclusters for highly efficient pH-universal electrocatalytic hydrogen evolution

Designing electrocatalysts with superior activity and stability to Pt/C for the highly efficient pH-universal electrochemical hydrogen evolution reaction (HER) still remains an urgent challenge. Herein, we report a facile plasma method for the preparation of defect-rich flexible carbon cloth decorated with ultralow-loading (0.1 wt%) PtRu alloyed nanoclusters (PtRu/CC-P) to resolve these problems. Remarkably, the developed PtRu/CC-P catalyst delivered a high mass activity of 3.77 A mg^-1 (η = 100 mV), almost 3.6 times higher than that of the benchmark HER electrocatalyst 20%Pt/C (1.05 A mg^-1). Meanwhile, it only required a low overpotential of 44 mV to achieve a current density of 10 mA cm^-2 in alkaline media. Systematic experimental and DFT calculation results revealed that the Pt-Ru bridge of PtRu alloyed nanoclusters in PtRu/CC-P can optimize the adsorption strength of HER intermediates at active sites, decrease the H₂O dissociation energy barrier, and consequently facilitate the HER kinetics. Inspiringly, when the PtRu content was increased to 1 wt%, PtRu/CC-P still exhibited a relatively low overpotential of 276 mV even at a high current density of 1000 mA cm^-2 and maintained excellent durability at a relatively high current density of 50-500 mA cm^-2 for more than 15 h in alkaline media. In addition, PtRu/CC-P also showed brilliant HER activity and stability in neutral and acidic media. This facile method provides a feasible route for the rational design of Pt-based alloyed catalysts toward industrial hydrogen production at all-pH values.

Ultrafast Porous Carbon Activation Promises High-Energy Density Supercapacitors

Activated porous carbons (APCs) are traditionally produced by heat treatment and KOH activation, where the production time can be as long as 2 h, and the produced activated porous carbons suffer from relatively low specific surface area and porosity. In this study, the fast high-temperature shock (HTS) carbonization and HTS-KOH activation method to synthesize activated porous carbons with high specific surface area of ≈843 m² g^-1 , is proposed. During the HTS process, the instant Joule heating (at a heating speed of ≈1100 K s^-1 ) with high temperature and rapid quenching can effectively produce abundant pores with homogeneous size-distribution due to the instant melt of KOH into small droplets, which facilitates the interaction between carbon and KOH to form controllable, dense, and small pores. The as-prepared HTS-APC-based supercapacitors deliver a high energy density of 25 Wh kg^-1 at a power density of 582 W kg^-1 in the EMIMBF₄ ionic liquid. It is believed that the proposed HTS technique has created a new pathway for manufacturing activated porous carbons with largely enhanced energy density of supercapacitors, which can inspire the development of energy storage materials.

Core-Shell Nanostructured Ru@Ir-O Electrocatalysts for Superb Oxygen Evolution in Acid

The design of highly active and durable catalysts for the sluggish anodic oxygen evolution reaction (OER) in acid remains an urgent yet challenging goal in water electrolysis. Herein, a core-shell nanostructured Ru@Ir-O catalyst with tensile strains and incorporated oxygens is introduced in the Ir shell that holds an extremely low OER overpotential of 238 mV at 10 mA cm^-2 in acid. The material also shows a remarkable 78-fold higher mass activity than the conventional IrO₂ at 1.55 V in 0.5 M H₂ SO₄ . Structural characterization and theoretical calculations reveal that the core-shell interaction and tensile strain cause band position shift and charge redistribution. These electronic factors furthermore optimize the bonding strength of O* and HOO* intermediates on the surface, yielding significantly boosted OER activity relative to the conventional IrO₂ .

Inverse Design of Materials by Machine Learning

It is safe to say that every invention that has changed the world has depended on materials. At present, the demand for the development of materials and the invention or design of new materials is becoming more and more urgent since peoples' current production and lifestyle needs must be changed to help mitigate the climate. Structure-property relationships are a vital paradigm in materials science. However, these relationships are often nonlinear, and the pattern is likely to change with length scales and time scales, posing a huge challenge. With the development of physics, statistics, computer science, etc., machine learning offers the opportunity to systematically find new materials. Especially by inverse design based on machine learning, one can make use of the existing knowledge without attempting mathematical inversion of the relevant integrated differential equation of the electronic structure but by using backpropagation to overcome local minimax traps and perform a fast calculation of the gradient information for a target function concerning the design variable to find the optimizations. The methodologies have been applied to various materials including polymers, photonics, inorganic materials, porous materials, 2-D materials, etc. Different types of design problems require different approaches, for which many algorithms and optimization approaches have been demonstrated in different scenarios. In this mini-review, we will not specifically sum up machine learning methodologies, but will provide a more material perspective and summarize some cut-edging studies.

Facile Fabrication of a Foamed Ag3CuS2 Film as an Efficient Self-Supporting Electrocatalyst for Ammonia Electrolysis Producing Hydrogen

Ammonia (NH₃) is one of the hydrogen carriers that has received extensive attention due to its high hydrogen content and carbon-free nature. The ammonia electro-oxidation reaction (AOR) and the liquid AOR (LAOR) are integral parts of an ammonia-based energy system. The exploration of low-cost and efficient electrocatalysts for the AOR and LAOR is very important but very difficult. In this work, a novel self-supporting AOR and LAOR bifunctional electrocatalyst of a Ag₃CuS₂ film is synthesized by a simple hydrothermal method. The Ag₃CuS₂ film without a substrate shows efficient catalytic activity and enhanced stability for NH₃ electrolysis in both aqueous ammonia solution and liquid ammonia, including an onset potential of 0.7 V for the AOR and an onset potential of 0.4 V for the LAOR. The density functional theory calculations prove that compared to Cu atoms, Ag atoms with appropriate charge density on the surface of Ag₃CuS₂ are more electrocatalytically active for NH₃ splitting, including the low energy barrier in the rate-determining *NH₃ dehydrogenation step and the spontaneous tendency in the N₂ desorption process. Overall, the foamed Ag₃CuS₂ film is one of prospective low-cost and stable electrocatalysts for the AOR and LAOR, and the self-supporting strategy without a substrate provides more perspectives to tailor more meaningful and powerful electrocatalysts.

An electrochemical modification strategy to fabricate NiFeCuPt polymetallic carbon matrices on nickel foam as stable electrocatalysts for water splitting

Electrochemical modification is a mild and economical way to prepare electrocatalytic materials with abundant active sites and high atom efficiency. In this work, a stable NiFeCuPt carbon matrix deposited on nickel foam (NFFeCuPt) was fabricated with an extremely low Pt load (∼28 μg cm⁻²) using one-step electrochemical co-deposition modification, and it serves as a bifunctional catalyst for overall water splitting and achieves 100 mA cm⁻² current density at a low cell voltage of 1.54 V in acidic solution and 1.63 V in alkaline solution, respectively. In addition, a novel electrolyte was developed to stabilize the catalyst under acidic conditions, which provides inspiration for the development of highly efficient, highly stable, and cost-effective ways to synthesize electrocatalysts.

Multiple metal elements immobilized into a carbon matrix to fabricate an ultra-stable water splitting electrocatalyst by one-step electrochemical modification.