Thermoelectric coolers utilizing the Peltier effect have dominated the field of solid-state cooling but their efficiency is hindered by material limitations. Alternative routes based on the Thomson and Nernst effects offer new possibilities. Here, we present a comprehensive investigation of the thermoelectric properties of 1T-TiSe2, focusing on these effects around the charge density wave (CDW) transition (≈ 200 K). The abrupt Fermi surface reconstruction associated with this transition leads to an exceptional peak in the Thomson coefficient of 450 μV.K−1 at 184 K, surpassing the Seebeck coefficient. Furthermore, 1T-TiSe2 exhibits a remarkably broad temperature range (170 − 400 K) with an average Thomson coefficient exceeding 190 μV.K−1, a characteristic highly desirable for the development of practical Thomson coolers with extended operational ranges. Additionally, the Nernst coefficient exhibits an unusual temperature dependence, increasing with temperature in the normal phase, which we attribute to bipolar conduction effects. The combination of solid-solid pure electronic phase transition to a semimetallic phase with bipolar transport is identified as responsible for the unusual Nernst trend and the unusually large Thomson coefficient over a broad temperature range.

Metal dichalcogenide based 2D materials, gained considerable attention recently as a hydrogen evolution reaction (HER) electrocatalyst. In this work, we synthesized MoSe2 based electrocatalyst via hydrothermal route with varying phase contents (1T/2H) and respective HER performances were evaluated under the acidic media (0.5M H2SO4), where best HER performance was obtained from the sample consisting of mixed 1T/2H phases, which was directly grown on a carbon paper (167mV at 10mA/cm2) Furthermore, HER performance of electrocatalyst was further improved by in-situ electrodeposition of Pt nanoparticles (0.15 wt%) on the MoSe2 surface, which lead to significant enhancement in the HER performances (133mV at 10mA/cm2). Finally, we conducted DFT calculations to reveal the origin of such enhanced performances when the mixed 1T/2H phases were present, where phase boundary region (1T/2H heterojunction) act as a low energy pathway for H2 adsorption and desorption via electron accumulation effect. Moreover, presence of the Pt nanoparticles tunes the electronic states of the MoSe2 based catalyst, resulting in the enhanced HER activity at heterointerface of 1T/2H MoSe2 while facilitating the hydrogen adsorption and desorption process providing a low energy pathway for HER. These results provide new insight on atomic level understanding of the MoSe2 based catalyst for HER application.

Regulating lithium (Li) plating/stripping behavior in three-dimensional (3D) conductive scaffolds is critical to stabilize Li metal batteries (LMBs). Surface protrusions and roughness in these scaffolds can induce uneven distributions of the electric fields and ionic concentrations, forming ’hot spots’. Hot spots may cause uncontrollable Li dendrites growth, presenting significant challenges to the cycle stability and safety of LMBs. To address these issues, we construct a Li ionic conductive-dielectric gradient bifunctional interlayer (ICDL) onto 3D Li-injected graphene/carbon nanotube scaffold (LGCF) via in situ reaction of exfoliated hexagonal boron nitride (fhBN) and molten Li. Microscopic and spectroscopic analyses reveal that ICDL consists of fhBN-rich outer layer and inner layer enriched with Li3N and Li-boron composites (Li-B). The outer layer utilizes dielectric properties to effectively homogenize the electric field, while the inner layer ensures high Li ion conductivity. Moreover, DFT calculations indicate that ICDL can effectively adsorb Li and decrease the Li diffusion barrier, promoting enhanced Li ion transport. The modulation of Li kinetics by ICDL increases the critical length of the Li nucleus, enabling suppression of Li dendrite growth. Attributing to these advantages, the ICDL coated LGCF (ICDL@LGCF) demonstrates impressive long term cycle performances in both symmetric cells and full cells.

Lithium metal batteries are the most promising next-generation energy storage technologies due to their high energy density. However, their practical application is impeded by serious interfacial side reactions and dendrite growth of lithium metal anode (LMA). Herein, copper 2,4,5-trifluorophenylacetate (CuTFPAA) is synthesized and used to stabilize LMA by in-situ constructing a dense and mixed-conductive interfacial protective layer. The in-situ formed passivated layer not only significantly inhibits interfacial side reactions by avoiding direct contact between LMA and electrolyte but also effectively suppresses lithium dendrite growth due to its high mechanical strength. As a result, the CuTFPAA-treated LMAs show greatly improved cycle stability under both high current density and high areal deposition capacity. Notably, the assembled liquid symmetrical cells with CuTFPAA-treated LMAs can stably work for more than 3000, 5000, and 4800 h at 1.0 mA cm‒2‒1.0 mAh cm‒2, 2.0 mA cm‒2‒5.0 mAh cm‒2, and 10 mA cm‒2‒5.0 mAh cm‒2, respectively. Furthermore, the assembled liquid full cell with a high LiFePO4 loading (~ 16.9 mg cm‒2) shows a significantly enhanced cycle life of 250 cycles with stable Coulombic efficiencies (> 99.1%). Moreover, the assembled all-solid-state lithium metal battery with a high LiNi0.6Co0.2Mn0.2O2 loading (~ 5.0 mg cm‒2) also exhibits improved cycle stability. These findings underline that the CuTFPAA-treated LMAs show great promise for high-performance lithium metal batteries.

This study investigates the electrochemical behavior of molybdenum disulfide (MoS2) as an anode in Li-ion batteries, focusing on the extra capacity phenomenon. Employing advanced characterization methods such as in situ and ex situ X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy, the research unravels the complex structural and chemical evolution of MoS2 throughout its cycling. A key discovery is the identification of a unique Li intercalation mechanism in MoS2, leading to the formation of reversible LixMoS2 phases that contribute to the extra capacity of the MoS2 electrode. Density function theory calculations suggest the potential for overlithiation in MoS2, predicting Li5MoS2 as the most energetically favorable phase within the lithiation-delithiation process. Additionally, the formation of a Li-rich phase on the surface of Li4MoS2 is considered energetically advantageous. After the first discharge, the battery system engages in two main reactions. One involves operation as a Li-sulfur battery within the carbonate electrolyte, and the other is the reversible intercalation and deintercalation of Li in LixMoS2. The latter reaction contributes to the extra capacity of the battery. The incorporation of reduced graphene oxide as a conductive additive in MoS2 electrodes notably improves their rate capability and cycling stability.

Organic materials, with low environmental impact and adaptable structures, are attractive for Hybrid capacitive deionization (HCDI). However, the scarcity of active sites and tendency to dissolve in water-based solutions remain significant challenges. Herein, we synthesized a polynaphthalenequinoneimine (PCON) polymer with stable long-range ordered framework and rough three-dimensional floral surface morphology, along with high-density active sites provided by C=O and C=N functional groups, enabling efficient redox reactions and achieving a high Na+ capture capability. The synthesized PCON polymer showcases outstanding electroadsorption characteristics and notable structural robustness, attaining an impressive specific capacitance of 500.45 F g-1 at 1 A g-1 and maintaining 86.1% of its original capacitance following 5000 charge-discharge cycles. Benefiting from the superior pseudocapacitive properties of the PCON polymer, we developed an HCDI system that not only exhibits exceptional salt removal capacity of 100.8 mg g-1 and a remarkable rapid average removal rate of 3.36 mg g-1 min−1, but also maintains 97% of its initial desalination capacity after 50 cycles, thereby distinguishing itself with the comprehensive performance that significantly surpasses reported organic deionization materials. Prospectively, the synthesis paradigm of the double active-sites polymer may be extrapolated to other organic electrodes, heralding new avenues for the design of high-performance desalination systems.

Nanofiltration (NF) membranes with exceptional ion selectivity and permeability are needed for the recovery of lithium from waste lithium-ion batteries (LIBs). Herein, inspired by the homogeneous microchannels in the skeletal structure of glass sponges, an innovative biomimetic sponge-like sub-nanostructured NF membrane was designed using a facile alkali-induced MXene (AMXene)-ethyl formate (EF)-induced bulk/interfacial diffusion decoupling strategy to simultaneously improve Li+/Co2+ selectivity and membrane permeability. The Li+/Co2+ separation factor (SLi,Co=24) in multi-ion solution of the engineered membrane was improved by an order of magnitude compared to that of an NF270 membrane (SLi,Co =2). The selectivity of Mg2+/Na+ (BNaCl/BMgCl2=286) and SO42-/Cl- (BNaCl/BNa2SO4=941) increased by 3~12 times, and the permeability (25.8 L m-2 h-1 bar-1) remained at a desirable level, beyond the current upper bound of the other reported cutting-edge membranes. The superior performance of the designed membrane was attributed to the limited release of amine monomers in bulk phase and the boosted interfacial diffusion by reducing interfacial energy barrier during the interfacial polymerization (IP) reaction, which were realized via the synergetic effects of AMXene and EF. This approach yielded a biomimetic sponge-like sub-nanostructured NF membrane with controlled homogeneous pore radii (0.202 nm) and a thickness as small as 16.08 nm, which led to high ion selectivity and permeability. The engineered membrane is capable of efficient separation and recovery of Li+/metal ions.

The surface reconstruction behavior of transition metal phosphides (TMPs) precursors is considered an important method to prepare efficient oxygen evolution catalysts, but there are still significant challenges in guiding catalyst design at the atomic scale. Here, the CoP nanowire with excellent water splitting performance and stability is used as a catalytic model to study the reconstruction process. Obvious double redox signals and valence evolution behavior of the Co site are observed, corresponding to Co2+/Co3+ and Co3+/Co4+ caused by auto-oxidation process. Importantly, the in-situ Raman spectrum exhibits the vibration signal of Co-OH in the non-Faradaic potential interval for oxygen evolution reaction, which is considered the initial reconstruction step . Density functional theory and ab initio molecular dynamics are used to elucidate this process at the atomic scale: First, OH- exhibits a lower adsorption energy barrier and proton desorption energy barrier at the configuration surface, which proposes the formation of a single oxygen group. Under a higher -O group coverage, the Co-P bond is destroyed along with the POx groups. Subsequently, lower P vacancy formation energy confirm that the Ni-CoP configuration can fast transform into highly active phase. Based on optimized reconstruction behavior and rate-limiting barrier, the Ni-CoP exhibit an excellent overpotential of 236 mV for OER and 1.59 V for overall water splitting at 10 mA cm-2, which demonstrates low degradation (2.62 %) during the 100 mA cm-2 for 100 h. This work provide systematic insights into the atomic-level reconstruction mechanism of TMPs, which benefit further design of water splitting catalyst.

Point source CO2 capture (PSCC) is a key technology to decarbonize various industries and direct air capture (DAC) is a potential technology to remove CO2 from the air. The chemical adsorption process using solid amine sorbents can be used for both PSCC and DAC. Solid amine sorbents have potential advantages as compared to the liquid amine sorbents. Solid amines can perform cyclic adsorption-desorption at a much lower energy than liquid amine such as alkanol amines. Environmental concerns related to monoethanolamine (MEA) can be eliminated by designing and upscaling solid amine sorbents. In the past few years, research groups worldwide have been involved in developing and designing cost-effective solid amine sorbents. However, most of them still need to be demonstrated for industrial applications. One of the potential support materials is silica gel which is commercially available and attractive as a low-cost support material for designing silica-based solid amine sorbents for large-scale CO2 capture applications. Different impregnation methods such as physical adsorption and covalent functionalization of silica surface have been used to attach amines and discussed. In this review, a comprehensive critical analysis of commercially available silica gel-supported solid amines is carried out. Silica gel-based solid amine sorbents are discussed and reviewed for desired factors such as adsorption capacity, adsorption and desorption conditions, and kinetics involved in these processes. Finally, a few recommendations are proposed for further development of low-cost, lower carbon footprint solid amine sorbents for large-scale deployment of CO2 capture technology.

Li/Mn-rich layered oxide (LMR) cathode active materials offer remarkably high specific discharge capacity (>250 mAh g-1) stemming from both cationic and anionic redox. The latter necessitates harsh charging conditions to high cathode potentials (>4.5 V vs. Li|Li+), which is accompanied by lattice oxygen release, phase transformation, voltage fade, and transition metal (TM) dissolution. In cells with graphite anode, TM dissolution is particularly detrimental as it initiates electrode crosstalk. Lithium difluorophosphate (LiDFP) is known for its pivotal role in suppressing electrode crosstalk through TM scavenging. In LMR || graphite cells charged to an upper cut-off voltage (UCV) of 4.5 V, effective TM scavenging effects of LiDFP is observed. In contrast, in cells with an UCV of 4.7 V, the scavenging effects is limited due to more severe TM dissolution compared an UCV of 4.5 V. Worth noting, the low solubility limit of the TM scavenging agents, e.g., PO43- and PO3F2-, which are the decomposition products of LiDFP, cannot scavenge additional TMs, even when higher LiDFP concentration are added to the electrolyte and can even worsen the performance.

Thick electrode, with its feasibility and cost-effectiveness, has attracted significant attention as a promising approach to maximize the energy density of lithium-ion batteries (LIBs). Through raising the mass loading of active materials without altering the fundamental chemical attributes, thick electrodes can boost the energy density of the batteries effectively. Nevertheless, as the thickness of the electrode increases, the ionic conductivity of the electrode decreases, leading to abominable polarization in the thickness direction, which severely hampers the practical application of a thick electrode. This work proposes a novel porous gradient design of high-performance thick electrodes for LIBs. By constructing a porous structure that serves as a fast transport pathway for lithium (Li) ions, the ion transport kinetics within thick electrodes are significantly enhanced. Meanwhile, a particle size gradient design is incorporated to further mitigate polarization effects within the electrode, leading to substantial improvements in reaction homogeneity and material utilization. Employing this strategy, we have fabricated a porous gradient nanocellulose-carbon-nanotube based thick electrode, which exhibits an impressive capacity retention of 86.7% at a high mass loading of LiCoO2 (LCO) active material (20 mg cm⁻²) and a high current density of 5 mA cm⁻².

Water electrolysis using renewable electricity is a promising strategy for high-purity hydrogen production. To realize the practical application of water electrolysis, an electrocatalyst with high redox properties and low cost is essential for enhancing the sluggish oxygen evolution reaction (OER). Herein, we fabricated Fe-doped nickel oxalate (Fe-NiC2O4) directly grown on Ni foam as an efficient electrocatalyst for the alkaline OER using a facile one-step hydrothermal method. Fe-NiC2O4 served as a precursor for obtaining highly active Fe-NiOOH via in-situ electrochemical oxidation. Consequently, 0.75Fe-NiOOH was demonstrated to be the optimal electrocatalyst, exhibiting outstanding OER activity with a low overpotential of 220 mV at a current density of 100 mA cm−2 and a Tafel slope of 20.5 mV dec-1. Furthermore, Fe-NiOOH maintained its OER activity without performance decay during long-term electrochemical measurements, owing to the phase transformation from NiOOH to γ-NiOOH. These performances significantly surpass those of recently reported transition metal-based electrocatalysts.

In this study, a framework for predicting the gas-sensitive properties of gas-sensitive materials by combining machine learning and density functional theory (DFT) has been proposed. The framework rapidly predicts the gas response of materials by establishing relationships between multi-source physical parameters and gas-sensitive properties. In order to prove its effectiveness, the perovskite Cs3Cu2I5 has been selected as the representative material. The physical parameters before and after the adsorption of various gases have been calculated using DFT, and then a machine learning model has been trained based on these parameters. Previous studies have shown that a single physical parameter alone is not enough to accurately predict the gas sensitivity of materials. Therefore, a variety of physical parameters have been selected for machine learning, and the final machine learning model achieved 92% accuracy in predicting gas sensitivity. It is important to note that although there have been no previous reports on the response of Cs3Cu2I5 to hydrogen sulfide, the resulting model predicts the gas response of H2S, which is subsequently confirmed experimentally. This method not only enhances the understanding of the gas sensing mechanism, but also has a universal nature, making it suitable for the development of various new gas-sensitive materials.

Decoupling electrical and thermal properties to enhance the figure of merit of thermoelectric materials underscores an in-depth understanding of the mechanisms that govern the transfer of charge carriers. Typically, a factor that contributes to the optimization of thermal conductivity is often found to be detrimental to the electrical transport properties. Here, we systematically investigated 26 dimeric MX2-type compounds (where M represents a metal and X represents a non-metal element) to explore the influence of the electronic configurations of metal cations on lattice thermal transport and thermoelectric performance using first-principles calculations. A principled scheme has been identified that the filled outer orbitals of the cation lead to a significantly lower lattice thermal conductivity compared to that of the partly occupied case for MX2, due to the much weakened bonds manifested by the shallow potential well, smaller interatomic force constants, and higher atomic displacement parameters. Based on these findings, we propose two ionic compounds, BaAs and BaSe2, to realize reasonable high electrical conductivities through the structural anisotropy caused by the inserted covalent X2 dimers, while still maintaining the large lattice anharmonicity. The combined superior electrical and thermal properties of BaSe2 lead to a high n-type thermoelectric ZT value of 2.3 at 500 K. This work clarifies the structural origin of the heat transport properties in dimeric MX2-type compounds and provides an insightful strategy for developing promising thermoelectric materials.

The growing demand for flexible, lightweight, and highly processable electronic devices makes high-functional conducting polymers such as poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT:PSS) an attractive alternative to conventional inorganic materials. However, considerable improvements are necessary to make conducting polymers a commercially viable choice. This study explores nanopatterning, as an effective strategy for enhancing polymer functionality, which results in substantial improvements in mechanical, thermal, optical, and electrical properties. Nanopatterned conducting polymers with manipulated electrical properties can be utilized in various fields, including thermoelectrics (TE). Introducing nanopatterning into thermoelectric polymers is challenging due to intricate technical hurdles and the necessity for individually manipulating the TE parameters such as electrical conductivity, Seebeck coefficient, and thermal conductivity. Here, enhanced TE performance is achieved by imposing array nanopatterns on PEDOT:PSS free-standing films using direct electron beam irradiation. Through nanopatterning, selective and independent control of electric and thermal transport in PEDOT:PSS was achieved. The e-beam irradiation transformed PEDOT:PSS from a highly-ordered quinoid to an amorphous benzoid structure, leading to a remarkable reduction in the thermal conductivity by 70% of that of the non-patterned PEDOT:PSS, without a significant reduction in electrical conductivity. Consequently, the thermoelectric figure of merit was enhanced by 60% compared to non-patterned PEDOT:PSS. The proposed nanopatterning methodology demonstrates a skillful approach to precisely manipulate the thermoelectric parameters, thereby improving the thermoelectric performance of conducting polymers, and promising utilization in cutting-edge electronic applications.

The exploration of heterostructures composed of two-dimensional (2D) transition metal dichalcogenide (TMDc) materials has garnered significant research attention due to the distinctive properties of each individual component and their phase-dependent unique properties. Using the plasma-enhanced chemical vapor deposition (PECVD) method, we analyze the fabrication of heterostructures consisting of two phases of molybdenum disulfide (MoS2) in four different cases. The initial hydrogen evolution reaction (HER) polarization curve indicates that the activity of the heterostructure MoS2 is consistent with that of the underlying MoS2, rather than the surface activity of the upper MoS2. This behavior can be attributed to an energy barrier arising from the physical contact resistance between the two different phases of MoS2 layers, which is mediated by van der Waals bonds. Remarkably, the energy barrier at the junction dissipates upon reaching a certain electrochemical potential, indicating surface activation from the top phase of MoS2 in the heterostructure. Notably, the 1T/2H MoS2 heterostructure demonstrates enhanced electrochemical stability compared to its metastable 1T-MoS2. This fundamental understanding paves the way for the creation of phase-controllable heterostructures through an experimentally viable PECVD, offering significant promise for a wide range of applications.

High-capacity nickel-rich layered oxides are promising cathode materials for high-energy-density lithium batteries. However, the poor structural stability and severe side reactions at the electrode/electrolyte interface result in unsatisfactory cycle performance. Herein, the thin layer of two-dimensional (2D) graphitic carbon-nitride (g-C3N4) is uniformly coated on the LiNi0.8Co0.1Mn0.1O2 (denoted as NCM811@CN) using a facile chemical vaporization-assisted synthesis method. As an ideal protective layer, the g-C3N4 layer effectively avoids direct contact between the NCM811 cathode and the electrolyte, preventing harmful side reactions and inhibiting secondary crystal cracking. Moreover, the unique nano-pore structure and abundant nitrogen vacancy edges in g-C3N4 facilitate the adsorption and diffusion of lithium ions, which enhances the lithium deintercalation/intercalation kinetics of the NCM811 cathode. As a result, the NCM811@CN-3wt% cathode exhibits 161.3 mAh g-1 and capacity retention of 84.6% at 0.5 C and 55 °C after 400 cycles and 95.7 mAh g-1 at 10 C, which is greatly superior to the uncoated NCM811 (i.e. 129.3 mAh g-1 and capacity retention of 67.4% at 0.5 C and 55 °C after 220 cycles and 28.8 mAh g-1 at 10 C). The improved cycle performance of the NCM811@CN-3wt% cathode is also applicable to solid-liquid-hybrid cells composed of PVDF:LLZTO electrolyte membranes, which show 163.8 mAh g-1 and the capacity retention of 88.1% at 0.1 C and 30 °C after 200 cycles and 95.3 mAh g-1 at 1 C.

Zinc metal anodes are gaining popularity in aqueous electrochemical energy storage systems for their high safety, cost-effectiveness, and high capacity. However, the service life of zinc metal anodes is severely constrained by critical challenges, including dendrites, water-induced hydrogen evolution, and passivation. In this study, a protective two-dimensional metal-organic framework interphase is in situ constructed on the zinc anode surface with a novel gel vapor deposition method. The ultrathin interphase layer (~1 µm) is made of layer-stacking 2D nanosheets with angstrom-level pores of around 2.1 Å, which serves as an ion sieve to reject large solvent-ion pairs while homogenizes the transport of partially desolvated zinc ions, contributing to a uniform and highly reversible zinc deposition. With the shielding of the interphase layer, an ultra-stable zinc plating/stripping is achieved in symmetric cells with cycling over 1000 h at 0.5 mA cm-2 and ~700 h at 1 mA cm-2, far exceeding that of the bare zinc anodes (250 and 70 h). Furthermore, as a proof-of-concept demonstration, the full cell paired with MnO2 cathode demonstrates improved rate performances and stable cycling (1200 cycles at 1 A g-1). This work provides fresh insights into interphase design to promote the performance of zinc metal anodes.