ACS Applied Energy Materials最新文献

Designing supported photocatalysts for photocatalytic hydrogen production is essential to overcome the time-consuming or expensive photocatalyst post-collection additional step. Herein, a copper-based Metal–Organic Framework (MOF)/TiO₂ (HKUST-1/TiO₂) composite photocatalyst, very promising for hydrogen generation, was encapsulated in chitosan (CS) spherical beads. These millimeter-sized photocatalytic beads were synthesized via a three-step method, and diffuse reflectance as well as Fourier-transform infrared spectroscopies assert that HKUST-1/TiO₂ is not altered by the synthesis process. Moreover, time-resolved microwave conductivity (TRMC) characterization proves that the charge carriers’ dynamics is not altered by the encapsulation of HKUST-1/TiO₂. The beads possess a good photocatalytic activity for hydrogen generation under UV–visible light. The number of beads and their stability with cycling were also investigated. A significantly higher hydrogen generation with hydrated beads (459 μmol/g/h) was measured compared to the one with dried beads (45 μmol/g/h) according to better water and hydrogen diffusion in the hydrated beads. The highest production rate reaches 854 μmol/g/h with 4 HKUST-1/TiO₂ CS beads loaded with 0.36 mg of photocatalyst per bead. Recyclability tests reveal good durability without a significant loss in efficiency.

Heterostructure materials with synergistic effects, abundant heterointerfaces, and excellent structural stability are promising for the development of advanced aqueous zinc batteries. Among them, one-/two-dimensional (1D/2D) heterostructures can combine the unique advantages of 1D and 2D materials. Herein, a series of 1D molybdenum/2D vanadium-based heterostructures are controllably constructed via the wet chemical process followed by thermal treatment. First, the controlled synthesis of 1D/2D heterostructures composed of 1D molybdenum trioxide (MoO₃) nanobelts and 2D hydrated vanadium pentoxide (V₂O₅·1.6H₂O) nanosheets is achieved. Experimental analyses and theoretical calculations reveal that the 1D (MoO₃)₁/2D (V₂O₅·1.6H₂O)₁ heterostructure (the component molar ratio: 1:1) exhibits superior electrochemical performance when used as the cathode for aqueous zinc-ion batteries. Then, using the 1D (MoO₃)₁/2D (V₂O₅·1.6H₂O)₁ heterostructure as the precursor, via in situ topological transformation, a series of 1D/2D heterostructures including 1D (MoS₂)₁/2D (V₂O₃)₁, 1D (MoN)₁/2D (V₂O₃)₁, 1D (MoO₂@MoO₃)₁/2D (V₂O₃)₁, and 1D (MoO₃)₁/2D (V₆O₁₃@V₂O₅)₁ are successfully synthesized. The 1D (MoS₂)₁/2D (V₂O₃)₁ heterostructure facilitates iodine cathode conversion and suppresses the polyiodide shuttle in aqueous zinc–iodine batteries. The controlled construction of 1D/2D heterostructures presents opportunities for energy storage and conversion applications, such as next-generation battery active materials and high-performance catalytic materials.

Charge carrier scattering in thermoelectric (TE) materials at room temperature and above is typically assumed to be due to acoustic phonons. However, recent studies indicate that this assumption needs to be taken with caution in many thermoelectric materials, as mechanisms such as polar optical phonon scattering and ionized impurity scattering can play an important role. In this work, we show that scattering information can be extracted from temperature-dependent TE data (Seebeck coefficient, electrical conductivity, and Hall coefficient) using standard multivariable optimization algorithms. Investigation of the scattering processes relies on the differences in their temperature and energy dependencies, which manifest as a variation of the absolute values and temperature slopes of the TE properties. Four major scattering processes, namely, scattering due to acoustic phonons, alloying, ionized impurities, and polar optic phonons, have been explored in this study. Standard analytical expressions for the scattering processes have been implemented within the framework of the Boltzmann transport equation, with the refined variables of interest being density of states mass, acoustic deformation potential, alloy scattering potential, and polar-optical phonon cutoff frequency. For the current study, we have analyzed materials with charge transport dominated by a single parabolic band. The accuracy of the predicted data was checked for a large range of parameters and carrier concentration values. Results indicate that the mean deviation in all of the parameters is less than 1%. Since no prior information about the refined parameters is necessary, the proposed technique can be a handy tool for identifying the dominant carrier scattering mechanisms in thermoelectric materials.

Magnesium batteries offer a promising alternative to lithium-ion systems, but suitable electrodes remain limited. Covalent organic frameworks (COFs) are attractive candidates due to their structural tunability and open channels for ion transport. We report a pyrene- 4,5,9,10-tetraone COF composite with carbon nanotubes as a Mg electrode, delivering 70 mAh g^–1 at 200 mA g^–1 and operating at 1.3 V. In situ Raman spectroscopy confirms carbonyl-centered redox on pyrene tetraone, supporting a Mg²⁺-driven carbonyl reduction. Compared with Li⁺, only partial carbonyl utilization occurs, attributed to steric and electrostatic constraints of divalent Mg²⁺. This incomplete conversion to magnesium-enolate inspires future work toward structural optimization.

Fluoride-ion batteries are a promising battery technology to achieve high energy densities exceeding those of traditional lithium-ion batteries. Reports on intercalation-based electrode materials for fluoride-ion batteries have mostly focused on cathode materials, while only a few intercalation-based anode materials have been reported. Their performance was heavily affected by carbon-based reductive side reactions, limiting reversibility and introducing high overpotentials. In this study, we present the successful substitution of carbon by metallic copper in solid-state FIBs, enabling the use of La₂NiO₃F₂, Pr₂NiO₃F₂, Sr₂TiO₃F₂, and Sr₃Ti₂O₅F₄ as intercalation-based anode materials by avoiding parasitic side reactions associated with the conductive carbon additive.

This paper presents a straightforward and effective strategy for achieving superior energy storage properties in lead-free dielectric ceramics using a single-element modification approach. Dielectric capacitors are widely used for energy storage applications; however, strontium bismuth titanate (SBT) remains relatively unexplored. In this study, we present the energy storage characteristics and underlying mechanism of relaxor ferroelectric SBT using Landau theory. Sr_0.7Bi_0.2TiO₃ (SR 0.70) and Sr_0.85Bi_0.10TiO₃ (SR 0.85) exhibit a tilted hysteresis loop demonstrating high discharge density. We designed systems to retain the cubic structure while maintaining structural stability without significant distortions. Our findings reveal that SR 0.85 ceramics exhibit exceptional frequency stability, a high dielectric constant, and significantly reduced dielectric loss. At an applied electric field of 227 kV/cm, the SR 0.85 ceramics attain a high energy storage density of 2.62 J/cm³, demonstrating their potential as advanced dielectric materials for energy storage technologies as compared to binary and ternary systems. The composition SR 0.85 exhibited outstanding thermal stability over a temperature range of 40–100 °C and maintained consistent performance across a broad frequency spectrum (1–1000 Hz). To further elucidate the underlying mechanisms that contribute to their superior energy storage performance, we correlated our experimental results with Landau’s theory. This analysis provides insights into the structural and dynamic factors for the utilization of high-performance single-element engineered lead-free systems for ultrahigh-energy storage applications that require miniaturization and integration in advanced pulse power systems.

A separator plays a critical role in alkaline water electrolysis (AWE or ALK) for high-efficiency hydrogen production. Traditional polyphenylene sulfide (PPS) separators suffer from the challenges of poor hydrophilicity, high internal resistance, and limited durability. Herein, a durable and hydrophilic PPS separator with a modified multiscale cross-linking coating layer is proposed. The coating layer is constructed through sequential codeposition of polydopamine/polyethylenimine, followed by interfacial polymerization involving modified ZrO₂ nanoparticles, PEI, and cyanuric chloride to create a robust organic–inorganic hybrid network with covalent cross-linking. The resulting separator exhibits a low area resistance (0.13 Ω cm^–2), and the electrolyzer achieves a high current density of 0.8 A cm^–2 at 2.05 V under 75 °C, arising from the enhancement of the separator’s hydrophilicity due to polar groups and hydrophilic ZrO₂ within the coating layer. The electrolyzer stability tests further confirm a stable voltage and minimal resistance increase over time, attributed to the synergistic effects of covalent cross-linking and ZrO₂ reinforcement, which enhance separators’ structural integrity and alkaline resistance. This study thus offers a scalable approach to designing high-performance ALK separators, with enhanced durability, enabling sustained hydrogen production under industrial conditions.

This work presents a flexible PVDF–NaClO₄–NaNO₃–Mg(OH)₂-based solid-state electrolyte for sodium metal batteries that operates at room temperature, prepared via a solution casting method. The electrolyte features a poly(vinylidene fluoride) (PVDF) host polymer matrix combined with an inorganic filler Mg(OH)₂, a flame-retardant agent, and dual sodium salts to enhance ion transport. The composite polymer electrolyte (CPE) exhibited a high ionic conductivity of 0.58 × 10^–3 S cm^–1 and a low activation energy of 0.15 eV. For a practical demonstration, a constructed PWC||PNM-3||Na cell achieved a discharge capacity of 148.0 mAh g^–1 at 0.1C and a high energy density of 503.99 Wh kg^–1.

The sluggish oxygen evolution reaction (OER), with its high theoretical potential (1.23 V vs RHE), complex four-electron transfer pathway, and substantial activation energy barrier, remains a major obstacle to the efficiency and cost-effectiveness of water electrolysis. Replacing OER with thermodynamically favorable anodic reactions involving more readily oxidized organic molecules (methanol) offers a promising strategy to reduce energy consumption. Here, a (1 wt %)r-GO@NiCrFe-BDC nanocomposite was grown on nickel foam via a solvothermal route, requiring a lower applied potential of ∼1.439 V vs RHE to acquire a current density of 25 mA/cm² for methanol electrooxidation compared to the oxygen evolution reaction (∼1.52 V vs RHE @ 25 mA/cm²). The r-GO was used at ultralow loading (1 wt %) as a conductivity-enhancing additive embedded within the NiCrFe-BDC framework rather than as an exposed carbon electrode. The electrochemical investigations reveal the distinct reaction kinetics of the oxygen evolution reaction and methanol electrooxidation. Notably, the methanol oxidation reaction (MOR) mechanism remains a subject of considerable ambiguity according to previously reported works. In this study, operando electrochemical impedance spectroscopy and distribution of relaxation time analysis (DRT) are applied to probe the hidden reaction kinetics (i.e., charge transfer, ion diffusion, adsorption/desorption, double-layer charging, and mass transport limitations) of the oxygen evolution reaction and methanol oxidation reaction. Systematic modulation of applied voltage and operating temperature enables the precise deconvolution of overlapping electrochemical processes through their characteristic relaxation times, thereby elucidating the distinct reaction kinetics governing the OER and MOR.

GeMnTe₂ has garnered significant attention due to its stable cubic structure and favorable thermoelectric properties. Herein, guided by the distinct electronic quality factor B_E, the band degeneracy of Ge_1.2Mn_0.8Te₂ is enhanced by alloying PbSe, which not only successfully increases the thermoelectric power factor but also synergistically reduces the lattice thermal conductivity. Further alloying Sb at the Ge site optimizes the carrier concentration, thereby achieving an optimum Seebeck coefficient and power factor while simultaneously decreasing the electronic thermal conductivity. As a result, a dimensionless thermoelectric figure of merit of 1.3 at 760 K is attained in the (Ge_1.05Mn_0.8Sb_0.15Te₂)_0.94(PbSe)_0.06 sample, underscoring diverse benefits of PbSe and Sb coalloying in enhancing the thermoelectric performance of GeMnTe₂-based materials.