Organic–inorganic hybrid phase change materials (PCMs) offer a promising approach to combine the high latent-heat storage capacity of hydrated salts with the phase stability of organic PCMs; however, interfacial incompatibility, phase separation, leakage, dehydration, and severe supercooling continue to limit their practical application. Herein, a shape-stable sodium acetate trihydrate/paraffin wax (SAT:PW) hybrid PCM was developed via an A200 silica-stabilized Pickering emulsion and subsequently encapsulated within an acrylamide-based hydrogel network. The Pickering emulsion enabled stable integration of the hydrophilic SAT phase and hydrophobic PW phase, while the hydrogel framework physically confined the hybrid PCM, suppressing leakage, reducing cumulative thermal mass loss, and improving thermal reliability during repeated phase transitions. Among the investigated formulations, SAT:PW90 provided the most favorable overall balance of latent-heat storage, crystallization performance, supercooling suppression, and leakage resistance in hydrogel encapsulation, exhibiting a melting peak temperature of 64.70 °C, a crystallization peak temperature of 47.74 °C, a melting enthalpy of 228.8 ± 1.0 kJ kg–1, a thermal conductivity of 0.556 ± 0.03 W m–1 K–1, and a low supercooling degree of 2.1 ± 0.85 °C. Under the investigated TGA conditions, hydrogel confinement reduced the cumulative mass loss to ∼1.25% at 75 °C and ∼2.2% at 155 °C, compared with ∼7.2 and ∼22%, respectively, for SAT:PW90, while retaining a melting enthalpy of 146.7 ± 1.5 kJ kg–1, a melting peak temperature of 63.96 °C, and a low supercooling degree of 4.0 °C. Following 100 heating–cooling cycles, the composite retained 95.8% of its initial melting enthalpy, with a supercooling degree of only 4.7 °C, demonstrating promising thermal reliability. These findings establish Pickering-emulsion stabilization combined with hydrogel confinement as an effective strategy for developing shape-stable hybrid PCMs for low-temperature solar thermal energy storage and building thermal-management applications.
Electrocatalytic nitrate reduction to ammonia (NO3–RR) offers a sustainable route for simultaneously removing nitrate pollutant and recovering value-added ammonia product under ambient conditions. However, the competitive hydrogen evolution reaction (HER) diverts active hydrogen species away from nitrate hydrogenation, thereby limiting the Faradaic efficiency and hydrogenation kinetics. In this work, we construct CuO nanoneedle arrays and employ Ar–ion irradiation to regulate oxygen vacancy concentration. Spectroscopic characterization reveals a progressive increase in the oxygen-vacancy concentration with increasing irradiation fluence. Among the investigated electrodes, the CuO electrode irradiated at 1 × 1015 ions cm–2 exhibits the best NO3–RR performance, delivering an NH3 Faradaic efficiency of 94.15% and a yield rate of 1.28 mg·N·h–1·cm–2 at a low potential of –0.1 V vs the reversible hydrogen electrode. Combining electron paramagnetic resonance measurements and *H scavenging experiment, we reveal that the enhanced performance originates from irradiation-induced oxygen vacancies, which not only facilitate the generation of active hydrogen species derived from water dissociation but also effectively utilize the active hydrogen species toward nitrate hydrogenation rather than H–H coupling. A preliminary techno-economic analysis estimates a levelized cost of ammonia of $0.935 kg–1 under the assumed conditions. We further extended this strategy to a coupled NO3–RR//EGOR system, in which replacing OER with ethylene glycol oxidation lowered the anodic overpotential. This work demonstrates that ion irradiation provides a controllable defect-engineering strategy for regulating active-hydrogen-mediated nitrate electroreduction on metal-oxide catalysts.
Copper sulfide (CuS) is regarded as a highly promising cathode candidate for rechargeable magnesium batteries (RMBs) owing to its high theoretical specific capacity, stable voltage plateau, and low-cost merit. Nevertheless, the sluggish Mg2+ diffusion kinetics and severe structural degradation of conventional cathode materials severely restrict their practical application. Herein, a two-dimensional CuS nanosheet (CuS NS) cathode is rationally designed via nanostructure engineering to address the above challenges. Compared with CuS nanoparticle (CuS NP) and commercial CuS, the CuS NS electrode exhibits enhanced reversible capacity, reduced electrochemical polarization, superior rate performance, and excellent long-cycle stability. Kinetic analyses demonstrate that the nanosheet architecture effectively shortens Mg2+ migration pathways, promotes interfacial charge transfer, and realizes a synergistic diffusion-capacitive magnesium storage mechanism. Combined with ex situ XRD, XPS, and HRTEM characterizations, a reversible multi-step conversion reaction mechanism is clearly elucidated. The CuS NS cathode undergoes sequential phase transformation of CuS → Cu2S → metallic Cu during discharging and reconstructs its original crystal structure after charging. This work establishes a clear structure–performance relationship of CuS-based cathodes, providing an efficient structural optimization strategy and in-depth mechanistic insight for the development of high-performance sulfide cathode materials for advanced magnesium-ion batteries.
Abstract This study examines the effects of post-treatment annealing (argon, vacuum, air; 200–500 °C) on electrodeposited IrRuOx porous transport electrodes (PTEs) using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The aim is to investigate how these treatments influence the material's composition, structure, and their respective impact on electrochemical properties. Electrochemical testing reveals atmosphere-dependent pathways: argon annealing improves stability up to 400 °C but produces Ir enrichment and heterogeneity at 500 °C that degrades performance; air annealing stabilizes oxidized species at 200 °C but yields larger activity and stability losses by 300 °C; and vacuum annealing at 200 °C preserves activity while improving stability. XPS characterization focuses on the analysis of Ir 4f, Ru 3d, and O 1s regions. For Ir 4f and Ru 3d spectra, simple metrics that didn’t involve fitting are explored, whereas for O 1s, deconvolution strategies are evaluated and a six-component model is adopted. In many cases, simple XPS metrics, binding energy (BE) and full width at half maximum (FWHM), capture trends that correlate with catalytic activity and stability, while detailed fitting is necessary to resolve complex oxygen speciation in other cases. Additionally, XPS-derived metrics are correlated with electrochemical performance using principal component analysis (PCA), highlighting patterns within a complex dataset. These results advance our understanding of XPS analysis of Ir-based catalysts, emphasize the importance of thorough and careful analysis, and highlight opportunities for combining simple metrics with multivariate analysis for the development of more efficient materials.
Abstract The disordered distribution of ionic groups in sulfonated polyimide (SPI) proton exchange membranes (PEMs) hinders the construction of efficient proton transport pathways and aggravates membrane swelling and methanol crossover, thereby limiting their practical application in direct methanol fuel cells (DMFCs). Herein, a protonated porphyrin-induced ionic aggregation regulation strategy is proposed to regulate ionic aggregation behavior and optimize the ionic microphase-separated morphology, enabling simultaneous enhancement of proton conductivity, dimensional stability, and methanol resistance. A series of SPI PEMs with different porphyrin contents was initially fabricated by incorporating porphyrin branching units into the copolymer backbone. In particular, the SPI-TAPP-2.0 membrane containing 2.0% porphyrin exhibited a high proton conductivity of 156.7 mS cm–1 at 80 °C, while maintaining a low swelling ratio of 42.7%. Consequently, the SPI-TAPP-2.0 membrane achieved a peak power density of 84.3 mW cm–2 and demonstrated long-term durability over 200 h with a low voltage decay rate of 0.85 mV h–1. The characterization results from small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), atomic force microscopy (AFM), and other techniques revealed that the enhanced performance was mainly attributed to the π–π stacking interactions among porphyrin units, which established ionic assembly centers, together with acid–base interactions between pyridinic nitrogen sites and sulfonic acid groups that regulated ionic aggregation and optimized the microphase-separated structure, ultimately constructing appropriately sized, highly interconnected, and selective hydrophilic proton transport networks. This work provides a strategy for optimizing microphase-separated morphology in SPI PEMs toward high-performance DMFC applications.
