Study of engineering electronic structure modulated non-noble metal oxides for scaled-up alkaline blend seawater splitting

Scaled-up industrial water electrolysis equipment that can be used with abundant seawater is key for affordable hydrogen production.The search for highly stable,dynamic,and economical electrocatalysts could have a significant impact on hydrogen commercialization.Herein,we prepared energy-efficient,scalable,and engineering electronic structure modulated Mn-Ni bimetal oxides(Mn_(0.25)Ni_(0.75)O)through simple hydrothermal followed by calcination method.As-optimized Mn_(0.25)Ni_(0.75)O displayed enhanced oxygen and hydrogen evolution reaction(OER and HER)performance with overpotentials of 266 and115 mV at current densities of 10 mA cm^(-2)in alkaline KOH added seawater electrolyte solution.Additionally,Mn-Ni oxide catalytic benefits were attributed to the calculated electronic configurations and Gibbs free energy for OER,and HER values were estimated using first principles calculations.In real-time practical application,we mimicked industrial operating conditions with modified seawater electrolysis using Mn_(0.25)Ni_(0.75)O‖Mn_(0.25)Ni_(0.75)O under various temperature conditions,which performs superior to the commercial IrO_(2)‖Pt-C couple.These findings demonstrate an inexpensive and facile technique for feasible large-scale hydrogen production.

Oxygen functionalization-assisted anionic exchange toward unique construction of flower-like transition metal chalcogenide embedded carbon fabric for ultra-long life flexible energy storage and conversion

The metal-organic framework(MOF)derived Ni–Co–C–N composite alloys(NiCCZ)were“embedded”inside the carbon cloth(CC)strands as opposed to the popular idea of growing them upward to realize ultrastable energy storage and conversion application.The NiCCZ was then oxygen functionalized,facilitating the next step of stoichiometric sulfur anion diffusion during hydrothermal sulfurization,generating a flower-like metal hydroxysulfide structure(NiCCZOS)with strong partial implantation inside CC.Thus obtained NiCCZOS shows an excellent capacity when tested as a supercapacitor electrode in a three-electrode configuration.Moreover,when paired with the biomass-derived nitrogen-rich activated carbon,the asymmetric supercapacitor device shows almost 100%capacity retention even after 45,000 charge–discharge cycles with remarkable energy density(59.4 Wh kg^(-1)/263.8μWh cm^(–2))owing to a uniquely designed cathode.Furthermore,the same electrode performed as an excellent bifunctional water-splitting electrocatalyst with an overpotential of 271 mV for oxygen evolution reaction(OER)and 168.4 mV for hydrogen evolution reaction(HER)at 10 mA cm−2 current density along with 30 h of unhinged chronopotentiometric stability performance for both HER and OER.Hence,a unique metal chalcogenide composite electrode/substrate configuration has been proposed as a highly stable electrode material for flexible energy storage and conversion applications.

Atomic Heterointerface Engineering of Nickel Selenide Confined Nickel Molybdenum Nitride for High-Performance Solar-Driven Water Splitting

A heterostructured electrocatalyst of small NiSe_(2) nanoparticles confined NiMoN nanorods(NiSe_(2)-NPs/NiMoN-NRs)is prepared to accelerate both the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in a same alkaline medium.The synergistic effects caused by the combination of merits derived from NiSe_(2) and NiMoN phases trigger an optimum electronic structure with high density of state at near Fermi level and enhance adsorption free energy,thereby resulting in excellent catalytic activities and strengthened working stability.The catalyst requires a low overpotential of 58 mV for HER and 241 mV for OER to reach 10 mA cm^(−2) in 1.0 M KOH electrolyte.A twoelectrode electrolyzer based on the developed catalyst shows outstanding cell voltage of 1.51 and 1.46 V to reach 10 mA cm^(−2) in 1.0 M and 30 wt%KOH solution at 25℃ for overall water splitting,respectively.In addition,the solardriven water splitting process delivers a high solar-to-H_(2) conversion efficiency of∼18.4%,impressively unveiling that the developed bifunctional catalyst is highly potential for overall water splitting to produce green hydrogen fuel.

Atomic Dispersion of Rh on Interconnected Mo_(2)C Nanosheet Network Intimately Embedded in 3D Ni_(x)MoO_(y) Nanorod Arrays for pH-Universal Hydrogen Evolution

Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(Ni_(x)MoO_(y)NRs)framework;we found that the introduction of both isolated Rh SAs and Ni_(x)MoO_(y)NRs adjusts the electrocatalytic function of the host Mo_(2)C toward the direction of being an advanced and highly stable electrocatalyst for efficient hydrogen evolution at pH-universal conditions.As a result,the proposed catalyst outperforms most recently reported transition metal-based catalysts,and its performance even rivals that of commercial Pt/C,as demonstrated by its ultralow overpotentials of 31.7,109.7,and 95.4 mV at a current density of 10 mA cm^(-2),along with its small Tafel slopes of 42.4,51.2,and 46.8 mV dec^(-1)in acidic,neutral,and alkaline conditions,respectively.In addition,the catalyst shows remarkable long-term stability over all pH values with good maintenance of its catalytic activity and structural characteristics after continuous operation.

Ni Single Atoms and Ni Phosphate Clusters Synergistically Triggered Surface-Functionalized MoS_(2)Nanosheets for High-performance Freshwater and Seawater Electrolysis

Two-dimensional metal dichalcogenides have been evidenced as potential electrocatalysts for hydrogen evolution reaction(HER);however,their application is limited by a poor oxygen evolution reaction(OER)activity due to insufficient number/types of multi-integrated active sites.In this study,we report a novel bifunctional catalyst developed by simultaneous engineering of single nickel atoms(Ni_(SA)) and nickel phosphate clusters(Ni_(Pi)) to synergistically trigger surface-functionalized MoS_(2) nanosheets(NSs)resulting in high reactivities for both HER and OER.The Ni_(SA)-Ni_(Pi)/MoS_(2)NSs material exhibits a fairly Pt-like HER behavior with an overpotential of 94.0 mV and a small OER overpotential of 314.0 mV to reach 10 mA cm^(-2) in freshwater containing 1.0 M KOH.Experimental results of the catalyst are well supported by theoretical study,which reveals the significant modulation of electronic structure and enrichment of electroactive site number/types with their reasonably adjusted free adsorption energy.For evaluating practicability,the Ni_(SA)-Ni_(Pi)/MoS_(2)NSs-based electrolyzer delivers effective operation voltage of 1.62,1.52,and 1.66 V at 10 mA cm^(-2) and superior long-term stability as compared to Pt/C//RuO_(2) system in freshwater,mimic seawater,and natural seawater,respectively.The present study indicates that the catalyst is a promising candidate for the practical production of green hydrogen via water electrolysis.

Liquid Metal Grid Patterned Thin Film Devices Toward Absorption‑Dominant and Strain‑Tunable Electromagnetic Interference Shielding

The demand of high-performance thin-film-shaped deformable electromagnetic interference(EMI)shielding devices is increasing for the next generation of wearable and miniaturized soft electronics.Although highly reflective conductive materials can effectively shield EMI,they prevent deformation of the devices owing to rigidity and generate secondary electromagnetic pollution simultaneously.Herein,soft and stretchable EMI shielding thin film devices with absorption-dominant EMI shielding behavior is presented.The devices consist of liquid metal(LM)layer and LM grid-patterned layer separated by a thin elastomeric film,fabricated by leveraging superior adhesion of aerosol-deposited LM on elastomer.The devices demonstrate high electromagnetic shielding effectiveness(SE)(SE_(T) of up to 75 dB)with low reflectance(SER of 1.5 dB at the resonant frequency)owing to EMI absorption induced by multiple internal reflection generated in the LM grid architectures.Remarkably,the excellent stretchability of the LM-based devices facilitates tunable EMI shielding abilities through grid space adjustment upon strain(resonant frequency shift from 81.3 to 71.3 GHz@33%strain)and is also capable of retaining shielding effectiveness even after multiple strain cycles.This newly explored device presents an advanced paradigm for powerful EMI shielding performance for next-generation smart electronics.

Bio‑imitative Synergistic Color‑Changing and Shape‑Morphing Elastic Fibers with a Liquid Metal Core

The systematic integration of color-changing and shape-morphing abilities into entirely soft devices is a compelling strategy for creating adaptive camouflage,electronic skin,and wearable healthcare devices.In this study,we developed soft actuators capable of color change and programmable shape morphing using elastic fibers with a liquid metal core.Once the hollow elastic fiber with the thermochromic pigment was fabricated,liquid metal(gallium)was injected into the core of the fiber.Gallium has a relatively low melting point(29.8℃);thus,fluidity and metallic conductivity are preserved while strained.The fiber can change color by Joule heating upon applying a current through the liquid metal core and can also be actuated by the Lorentz force caused by the interaction between the external magnetic field and the magnetic field generated around the liquid metal core when a current is applied.Based on this underlying principle,we demonstrated unique geometrical actuations,including flower-like blooming,winging butterflies,and the locomotion of coil-shaped fibers.The color-changing and shape-morphing elastic fiber actuators presented in this study can be utilized in artificial skin,soft robotics,and actuators.

Spacesuit Textiles from Extreme Fabric Materials:Aromatic Amide Polymer and Boron Nitride Nanotube Composite Fiber for Neutron Shielding and Thermal Management

Space exploration provides unparalleled opportunities for unraveling the mysteries of our origins and exploring planetary systems beyond Earth.Long-distance space missions require successful protection against significant radiation exposure,necessitating the development of effective radiation shielding materials.This study developed aromatic amide polymer(AAP)and boron nitride nanotube(BNNT)composite fibers using lyotropic liquid crystal(LLC)and industrially viable wet-spinning processes.The uniaxially oriented 1D composite fibers provide the necessary continuity and pliability to fabricate 2D macroscopic textiles with low density(1.80 g cm-3),mechanical modulus(18.16 GPa),and heat stability(up to 479℃),while exhibiting the improved thermal neutron absorption cross-section with thermal neutron-shielding performance(0.73 mm^(-1)).These composite textiles also show high thermal conductivity(7.88 W m^(-1)K^(-1))due to their densely packed and uniaxially oriented structures.These enhanced characteristics render the fibers a highly promising material for space applications,offering robust protection for both astronauts and electronics against the dual threats of radiation and heat.

Water-based direct photopatterning of stretchable PEDOT:PSS using amphiphilic block copolymers

The use of water-based chemistry in photolithography during semiconductor fabrication is desirable due to its cost-effectiveness and minimal environmental impact,especially considering the large scale of semiconductor production.Despite these benefits,limited research has reported successful demonstrations of water-based photopatterning,particularly for intrinsically water-soluble materials such as Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)due to significant challenges in achieving selective dissolution during the developing process.In this paper,we propose amethod for the direct patterning of PEDOT:PSS in water by introducing an amphiphilic Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)(PEO-PPO-PEO,P123)block copolymer to the PEDOT:PSS film.The addition of the block copolymer enhances the stretchability of the composite film and reduces the hydrophilicity of the film surface,allowing for water absorption only after UV exposure through a photoinitiated reaction with benzophenone.We apply this technique to fabricate tactile and wearable biosensors,both of which benefit fromthe mechanical stretchability and transparency of PEDOT:PSS.Our method represents a promising solution for water-based photopatterning of hydrophilic materials,with potential for wider applications in semiconductor fabrication.

Boost Up the Mechanical and Electrical Property of CNT Fibers by Governing Lyotropic Liquid Crystalline Mesophases with Aramid Polymers for Robust Lightweight Wiring Applications

Monofilament type of polyaromatic amide(PA)and carbon nanotube(CNT)composite fibers is presented.A concept of a lyotropic liquid crystal(LLC)constructed via a spontaneous self-assembly is introduced to mitigate the extremely low com-patibility between PA and CNT.These approaches provide an effective co-processing route of PA and CNT simultaneously to fabricate the uniform,continuous,and reliable composite fibers through a wet-spinning.Interestingly,the addition of a small amount PA into the dope solution of CNT governs the LLC mesophase not only in a spinneret stage but also in a coagulant region.Thus,the developed PA/CNT composite fibers have the high uniaxial orientational order and the close interfacial packing compared to the pure CNT fibers.The PA/CNT composite fibers achieve the outstanding tensile strength,electrical conductivity,and electrochemical response,while maintaining a lightweight.They also exhibit the chemical,mechanical,and thermal robustness.All of these advantages can make flexible,sewable,and washable PA/CNT composite fibers ideal nanocomposite materials for use in next-generation information and energy transporting system by replacing conventional metal electrical conductors.