ACS Applied Energy Materials最新文献

The efficiency of mixed lead–tin perovskite solar cells has increased rapidly, thanks to efficient passivation strategies of bulk and interfacial defects. For example, this occurs at the hole-transport layer and the perovskite interface. Here, we compare the self-assembled monolayers and multilayers (SAMs), [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and methylphosphonic acid (MPA), to a PEDOT:PSS layer at the rear interface of a MA-free narrow band gap perovskite in single-junction (SJ) and all-perovskite tandem solar cells. PEDOT:PSS-based devices show the best power conversion efficiency of 14% in SJ and 17.2% in all-perovskite tandem architecture. By using photoluminescence and ultraviolet photoelectron spectroscopy, we show that this behavior is due to better energy alignment at the PEDOT:PSS/PK than the SAM/PK interface. However, SAMs also show lower nonradiative recombination rates at this interface. The results identify the limits of the effectiveness of 2PACz and MPA in mixed lead–tin MA-free perovskite solar cells and confirm the need for other SAMs with improved energy-level alignment while maintaining their passivating properties.

Mg₃Sb₂ Zintl compounds have emerged as promising thermoelectric materials due to their favorable electronic structures and low lattice thermal conductivity. However, strong carrier scattering, including ionized impurity and grain boundary scattering, suppresses mobility and limits the power factor. This study reveals that Zn doping plays a crucial role in tuning carrier scattering mechanisms in n-type Mg₃(Sb,Bi)₂. The substitution of Mg with Zn weakens ionized impurity scattering, facilitating charge transport and increasing carrier mobility from ∼72 to ∼135 cm² V^–1 s^–1. As a result, a high power factor of ∼2089 μW m^–1 K^–2 is achieved at 573 K in Mg_3.155Zn_0.045Sb_1.5Bi_0.49Te_0.01. Furthermore, Zn incorporation introduces localized lattice distortions and promotes the formation of high-density dislocations, which intensify phonon scattering and significantly suppress lattice thermal conductivity to ∼0.54 W m^–1 K^–1 at 773 K. These synergistic enhancements contribute to an optimized thermoelectric performance, yielding a peak ZT of 1.71 at 773 K and an average ZT of 1.21. The estimated conversion efficiency reaches 13% under a 470 K temperature gradient, highlighting Zn doping as an effective strategy for advancing Mg₃(Sb,Bi)₂-based thermoelectric materials toward high-temperature energy harvesting applications.

Liquid ammonia electrolysis is a promising route to generate hydrogen. It is performed at room temperature to obtain highly purified hydrogen isolated at the cathode. Theoretically, hydrogen can be extracted by electrolyzing liquid ammonia at a voltage of 0.077 V vs H₂/NH₃ at 25 °C. However, the onset voltage exceeds the theoretical value in practice owing to the high overpotential associated with the anodic reaction in the amide ion oxidation process. In this study, we prepared high entropy alloy IrRhRuCoNi powder to serve as an anodic catalyst. This powder exhibited a high specific surface area (66.2 m²/g) and was synthesized by reducing the oxide precursor in molten LiCl–CaH₂ at 600 °C. A comprehensive structural analysis involving X-ray diffraction and scanning/transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy revealed that the synthesized powder consisted primarily of a face-centered cubic structure with a well-dispersed mixture of Ir, Rh, Ru, Co, and Ni at the nanoscale. The IrRhRuCoNi powder was then supported on carbon nanotubes and used as an anodic catalyst in liquid ammonia electrolysis. Chronoamperometry measurements demonstrated that the anodic catalyst exhibited current densities comparable to a commercial ruthenium black catalyst, reaching 0.93/4.20 mA/cm² at 0.3/0.5 V vs H₂/NH₃ after 300 s. Furthermore, the catalytic performance remained stable over a 50 h period. Notably, the alloyed catalyst maintained high current densities of 1.03/3.50 mA/cm² at 0.3/0.5 V vs H₂/NH₃ even during cyclic voltammetry measurements at an exceptionally slow scan rate of 2 mV/min from 0 to 0.5 V vs H₂/NH₃. In contrast, the commercial ruthenium black catalyst exhibited substantial decreases in current densities under these conditions. These results demonstrate the superior performance of the synthesized high entropy alloy IrRhRuCoNi catalyst for liquid ammonia electrolysis compared to the single Ru catalyst, which is likely attributed to the synergistic effects arising from the multielemental composition.

The n-type Mg₃(Sb,Bi)₂-based thermoelectric materials are promising candidates for medium-temperature power generation due to their low cost, nontoxicity, and high performance. However, their large-scale application in thermoelectric devices is significantly hindered by poor long-term stability, resulting from electrode interface degradation. Effective contact interfaces in thermoelectric devices require high bonding strength, low interfacial resistivity, and exceptional stability. Therefore, the development of efficient and reliable thermoelectric interface materials is crucial for the practical application of these devices. Conventional approaches to forming interfacial barrier layers mainly rely on thermodynamic equilibrium, which often overlook the critical roles of interfacial reactions and diffusion kinetics. In this study, molecular dynamics simulations were employed to uncover the underlying mechanisms responsible for the high stability of the Mg₂Ni barrier layer and its interface with thermoelectric materials. The Mg₂Ni/Mg_3.21Sb_1.5Bi_0.5Y_0.04 thermoelectric device exhibited excellent performance, with a low contact resistance of 11 μΩ·cm², a high output power density of 1.2 W·cm^–2, and an energy conversion efficiency of 5% at a temperature difference of ΔT = 373 K. This strategy is applicable to other thermoelectric materials, offering valuable insights for designing barrier layers in diverse thermoelectric systems.

The study of luminous materials having the capacity to emit light via many emission pathways has become a priority in materials research, spurred by the demand for increased performance in optoelectronic and medical applications. Traditional luminous materials are usually limited to single emission channels, restricting their performance and applicability. Multiemissive materials, on the other hand, can display fluorescence, charge transfer (CT) emission, room temperature phosphorescence (RTP), and delayed fluorescence (DF), providing a potential means to overcome these limits. In this study, we reported a class of 9-fluorenone derivatives tailored to utilize these diverse emission mechanisms. We acquired exact control over the relative contributions of each emission pathway by purposely modifying the molecular architecture─for example, adding heavy atoms to boost spin–orbit coupling and introducing electron-withdrawing groups to influence electronic states. The resulting compounds possessed high fluorescence quantum yields, extended RTP durations in the microsecond region, and efficient DF lifetimes in the millisecond domain. Furthermore, by altering molecular structure and external environmental circumstances, their emission spectra can be fine-tuned from visible to near-infrared. In addition, time-dependent density functional theory (TDDFT) calculations were performed to investigate the excited states and their roles in the different emission channels, providing deeper insight into the mechanisms underlying the observed photophysical behaviors. The adjustable character of these materials is further emphasized by their sensitivity to external stimuli such as solvent polarity and temperature, allowing for the selective enhancement of specific emissive routes. These 9-fluorenone derivatives are suited for advanced applications in organic light-emitting diodes (OLEDs), bioimaging, and molecular sensing technologies due to their stimuli-responsive features. Our findings emphasize the importance of combining molecular design and environmental factors to optimize multipathway emission, providing a versatile platform for the development of next-generation luminescent materials with broad applicability in both fundamental research and practical applications.

Aluminum (Al) is a highly promising material for lithium-ion batteries (LIBs) anodes due to its high specific capacity, excellent electrical conductivity, and low cost. However, its practical application is hindered by significant volume changes during cycling, which cause electrode crushing and numerous penetration cracks. In this study, we design a laminated Al foil and incorporated it into lithium–aluminum (Li//Al) half-cells, which retain a long cyclic stability of 300 cycles at a current density of 1 mA cm^–2 and an areal capacity of 1 mA h cm^–2. The laminated Al foil exhibits denser grain boundaries, leading to enhanced lithiation uniformity. Additionally, the laminated structure effectively alleviates stress concentration during lithiation and delithiation, diverting major cracks into smaller, multidirectional ones. This structural improvement significantly enhances the stability of the Al foil anode during cycling. The findings offer valuable insights for optimizing metal foil anode designs, which could contribute to advancements in LIBs technology, particularly in improving specific energy.

LiBH₄ has attracted significant interest due to its high-hydrogen storage capacity (18.5 wt % H₂). However, its practical application is severely impeded by the high dehydrogenation temperature, sluggish hydrogen release kinetics, and poor reversibility. In this work, a graphene-supported rodlike FeF₂/FeO_X additive (FeF₂/FeO_X@G) is prepared and introduced into LiHB₄ by a simple ball-milling. With an optimized LiBH₄-to-FeF₂/FeO_X@G weight ratio of 7:3, the 7LiBH₄-3(FeF₂/FeO_X@G) system starts dehydrogenation at a low temperature of 100 °C below and 8.7 wt % H₂ is released upon heating to 400 °C, while 1.1 wt % H₂ is released for pristine LiBH₄. Moreover, the system releases rapidly 7.0 wt % H₂ at 350 °C within 80 min, and a dehydrogenation capacity of 5.5 wt % is reached after 10 reversible hydrogen absorption and desorption cycles. The in situ formed FeB, Li₃BO₃, and Fe₂B during the first dehydrogenation process acted as a synergistic catalysis, effectively improving the reversible hydrogen storage of LiBH₄. This work provides insights into the design of unique additives to introduce multiple catalyst synergies to enhance the hydrogen storage performance of LiBH₄.

Sodium storage mechanisms and microstructures play a key role in improving the sodium storage capacity of hard carbon (HC) anodes; however, the storage mechanisms of sodium ions in coal-carbon-derived HC and the effective regulation of microstructures at the molecular level are still scarce. In this work, it is proposed for the first time that the coaling effect affects the microstructure and the Na⁺ diffusion coefficient in coal-derived HCs during their discharge by grafting aryl rings and oxygen-containing functional groups within and between the main chains of the precursors. We propose and confirm two Na⁺ storage mechanisms that are closely related to the coalisation effect. Aromatic rings and oxygen-containing functional groups induce Na⁺ aggregation during Na⁺ diffusion, leading to the formation of metal clusters in low-voltage regions. Therefore, the effects of aromatic rings and oxygen-containing functional groups on the local microstructure of HCs should be considered when designing HCs. In this work, HCs with specific graphite microcrystalline structures were prepared by screening coal precursors, and constraints between graphite microcrystalline parameters and precursors were revealed. This work provides theoretical guidance to study the storage mechanism of Na⁺ through the coalisation effect and offers new ideas for the development of high-performance coal-derived anodes for sodium-ion batteries.