Science China Materials最新文献

Recently, the power conversion efficiency (PCE) of organic solar cells (OSCs) has been substantially advanced by optimizing the acceptors and cathode interface layers (CILs). Perylene diimide (PDI) has been universally used in acceptors and CILs for OSCs owing to its chemical and photothermal stability, structural tunability, and high electron mobility. Nevertheless, the high planarity of PDI tends to result in excessive aggregation, which suppresses the PCE of the OSCs. Notably, the bay-functionalization strategy of PDI can optimize the light absorption properties, charge transfer (CT), and aggregation behavior, which dramatically boost the PCE of OSCs. Here, a systematic summary of acceptors and CILs based on the bay-substitution of PDI is reviewed. First, the progress history and working principle of OSCs are reviewed, and the mechanisms of the acceptors and CILs, as well as the functional properties of the disparate positions of PDI, are elaborated. Second, the relationship between the performance and structure of the bay-modified PDI acceptors and CILs was discussed in depth. Finally, the conclusions and outlooks of acceptors and CILs for bay-substituted PDI are presented. This review provides valuable insights for optimizing the performance of OSCs by modifying the PDI in bay regions.

Lithium (Li) metal anodes (LMAs) have garnered significant attention due to their exceptionally high theoretical capacity and low redox potentials. However, the uncontrolled growth of Li dendrites and substantial volume expansion severely undermine their cycling stability, particularly at elevated current densities. Herein, we develop a lithiophilic 3D Li host by incorporating ZnO/ZnSe heterostructures onto brass fibers (ZnO/ZnSe@Brass), designed to enhance the fast-charging capabilities of Li metal batteries. This hierarchical structure effectively mitigates volume expansion and reduces local current density during lithiation. The uniformly distributed ZnO/ZnSe functions as a lithiophilic skin for the Li anode, facilitating smooth and dense Li deposition. Notably, the in situ formed solid electrolyte interphase, enriched with Li₂Se and Li₂O, provides high ionic conductivity and superior mechanical strength, thereby accelerating ion transport and charge transfer kinetics. Benefiting from the synergistic effects of the ZnO/ZnSe@Brass host, the resulting Li symmetric cell exhibits robust cycling performance exceeding 10,000 cycles (20 mA cm⁻²/1 mA h cm⁻²) and supports fast charging rates at an ultra-high current density of 80 mA cm⁻². When paired with LiFePO₄, the full-cell demonstrates excellent cycle life (>500 cycles at 2 C) and outstanding rate performance. This finding of ZnO/ZnSe@Brass as a Li host sheds light on the design of advanced LMAs for fast-charging Li metal batteries.

Graphdiyne (GDY), known for its tunable intrinsic bandgap, high charge carrier mobility, and broad-spectrum absorption, has garnered significant attention for photocatalytic hydrogen evolution. However, GDY/wide-band semiconductor photocatalysts suffer from limitations, including low doping concentrations and insufficient absorption in the visible-to-near-infrared (Vis-NIR) region, which restricts full-spectrum energy utilization. To address these challenges, we designed and synthesized a functional graphdiyne quantum dots (PG-QDs) incorporating perylene diimide (PDI) units. These PG-QDs exhibit tailored spectral absorption, reducing competition with wide-band semiconductors for UV light while enhancing Vis-NIR absorption and photothermal conversion performance. PG-QDs overcame the doping concentration limitations of conventional GDY-based photocatalysts, achieving an optimal doping ratio of 15% without suppressing hydrogen evolution activity. The pronounced photothermal effect effectively suppressed the recombination of photogenerated carriers and enhanced charge carrier separation efficiency. The hydrogen evolution rate reached 12.69 mmol g⁻¹ h⁻¹, over thirty times higher than P25. This study presents a novel strategy for improving the full-spectrum energy utilization of GDY-based photocatalysts.

Phonon management in van der Waals (vdW) layered materials has become an area of increasing demand, driven by rapid advancements in electronic and optoelectronic devices. A fundamental challenge in the phonon management of these materials is the effective harvesting of phonons between layers to minimize energy dissipation. Here, we demonstrate a novel phonon energy harvesting strategy in vertically stacked transition metal dichalcogenide (TMD) homobilayers, whose constituent monolayers are prepared individually by mechanical exfoliation (ME) and chemical vapor deposition (CVD) methods. In these systems, owing to the defect-induced asymmetry of phonon populations between layers, the phonon energy can be transferred from CVD monolayers to ME monolayers and then sufficiently utilized to promote the trion-to-exciton conversion in homobilayers for significant photoluminescence (PL) enhancement. The degree of such PL enhancement can be further regulated by varying either the trion or phonon populations involved in the conversion process. This strategy is universally applicable to different TMD homobilayers, presenting a new avenue for phonon energy harvesting in vdW layered materials.

Transition metal dichalcogenides (TMDs) have widespread applications in the fields of optoelectronics and catalysis. Generally, 1T phase TMDs have more edge active sites than 2H phase TMDs and thus exhibit superior catalytic efficiency. However, it remains challenging to prepare 1T phase TMDs to date. In this study, we found that when two 2H phase tungsten disulfide (2H-WS₂) grains with large crystallographic orientation differences (>10°) come into contact at a temperature of 1000 °C, they can combine and further transform into one pure 1T phase tungsten disulfide (1T-WS₂) grain without crystallographic orientation differences. The first-principles calculation showed that at a temperature lower than 280 K, the 2H-WS₂ is a stable phase and 1T-WS₂ is a metastable phase. But when the temperature is higher than 280 K, their relative stability turns. In the kinetic analysis of 2H to 1T phase nucleation, homogeneous nucleation needs to cross the energy barrier of 2.314 eV, while the heterogeneous nucleation of two nanosheets in contact only needs to cross the energy barrier of 0.005 eV, which is more prone to phase transformation. This work presents a novel approach for synthesizing 1T-WS₂ and may provide a strategy for synthesizing other 1T phase TMDs.

Covalent organic frameworks (COFs) are promising candidates for the rapid purification of toxic pollutants and mitigation of radioactive iodine leakage in nuclear accidents. In particular, COFs constructed from meta-position monomers can form clover-like morphology, increasing the specific surface area and providing multidimensional diffusion pathways for iodine. Herein, two nitrogen-rich COFs (DFPT-COF and DFPB-COF) featuring well-defined cloverlike nanochannels were successfully fabricated, demonstrating exceptional iodine capture performance. Compared to DFPB-COF, DFPT-COF exhibits better iodine capture performance (5.58 g g⁻¹ for I₂ vapor) due to its large specific surface area and rich nitrogen adsorption sites. Moreover, the adsorption dynamics of DFPT-COF for liquid iodine follow a pseudosecond-order kinetic model and the adsorption isotherm model complies with the Langmuir model. Notably, DFPT-COF exhibited excellent renewable adsorption performance, suggesting its potential as a sustainable and efficient green adsorbent for iodine in nuclear waste management.

Inverted perovskite solar cells (PSCs) have emerged as promising photovoltaic candidates because of their high efficiency and cost-effective fabrication. However, abundant defects and inefficient charge transport critically compromise the device efficiency and stability. Phosphonic acid-based multifunctional molecules, mainly as self-assemble monolayer, have recently been demonstrated to be useful in improving the device performance of the inverted PSCs. Herein, we designed and synthesized a new multifunctional molecule, (2-(3,6-bis(trifluoromethoxy)-9H-carbazol-9-yl)ethyl)phosphonic acid (M28) as additive in perovskite precursor solution to fabricate high-efficiency and stable inverted PSCs. Through spontaneous segregation toward the buried interface and grain boundaries (GBs), M28 affords threefold roles in enhancing device performance: (1) slowing the crystallization rate and enlarging the grain sizes to improve the perovskite film quality, (2) passivating the defects at buried interface and GBs to suppress charge recombination, (3) inducing an extra electric field at the buried interface through p-type doping to promote hole transport. The resulting devices thus achieved a remarkable power conversion efficiency of 25.96% and impressive long-term operational stability: maintaining 80% of their initial efficiency after 1500 h tracking at the maximum power point. This work emphasizes the importance of exploration of new types of functional molecules in advancing PSCs.

Biomass-derived hard carbons (HCs) are promising anodes for sodium-ion batteries (SIBs) due to their low cost, renewable nature, and structural stability, yet their practical application is hindered by a low initial Coulombic efficiency (ICE) and inadequate rate capability. Herein, we report a tri-functional nitric acid treatment coupled with one-step carbonization to synthesize a hard carbon with a sp²-C-dominated structure. The process not only eliminates impurities but also selectively dissolves lignin in the biomass, thereby promoting the alignment of graphite microcrystals. At the same time, edge-N and C=O groups are grafted onto the carbon skeleton, which together produce an HC with an optimized interlayer spacing and abundant closed micropores. These structure modifications collectively increase Na⁺ adsorption kinetics in the sloping region and enable efficient sodium storage in the low-voltage plateau region, yielding a high ICE of 91.69% and a remarkable rate capability, with 83.9% capacity retention at 600 mA g⁻¹. A full SIB cell using this HC anode with a Na₃V₂(PO₄)₃ cathode delivers an energy density of 213.14 Wh kg⁻¹, demonstrating its practical potential. This work offers a simple and scalable engineering strategy to overcome the performance vs. manufacturing cost dilemma in developing HC anodes.

MXene-based multilayered composite films show great promise in electromagnetic interference (EMI) shielding field, but the trade-off between mechanical properties, oxidation resistance and EMI shielding performance remains a huge challenge. Herein, inspired by the architecture of millefeuille, alternating multilayered MXene/carbon nanotube (CNT) films were successfully prepared using an alternating vacuum-assisted filtration method, in which the alternating CNT layers not only act as the mechanical frame and oxidation barrier, but also synergistically enhance the EMI shielding effect of MXene layers through the distinctive “absorption-reflection-reabsorption” mechanism. By optimizing the alternating multilayered structure, the MXene/CNT film with a thickness of 36 µm can achieve a remarkable EMI shielding effectiveness (SE) of 81.4 dB across the frequency range of 8.2–26.5 GHz. Meanwhile, the mechanical strength and toughness of the MXene/CNT film reach 83.4 MPa and 7.20 MJ/m³, respectively. Moreover, the CNT layer can effectively isolate MXene layer from oxygen, thus enabling the fire/oxidation resistance of the multilayer film in complex environments. Besides, the multilayered composite film exhibits impressive Joule heating capacity, which can reach 237 °C within 10 s at an applied voltage of only 2.0 V. Therefore, the alternating multilayered MXene/CNT film breaks through the performance balance limit, showing a great prospect for the future.

The development of high-performance, eco-friendly, and multifunctional electromagnetic interference (EMI) shielding nanocomposites is highly desirable. Recently, transition metal/nitrides (MXenes) have showcased great potential in constructing EMI shields, but are restricted by low yield, limited utilization efficiency, and cost-ineffective preparation for practical applications. This work introduces a novel nanocomposite film comprising “waste” MXene sediments (MS) and sustainable cellulose nanofibers (CNFs), fabricated through a simple, straightforward casting approach. The nanocomposites not only enhance the utilization of MXene layers but also deliver exceptional EMI shielding effectiveness (SE), with the 80 wt.% MS/CNF nanocomposite film achieving 52.3 dB X-band SE at just 0.57 mm thickness. Notably, the EMI SE can be precisely tuned over a broad frequency range, including the X-, Ku-, K-, and Ka-bands, where the nanocomposite consistently exceeds 53.9 dB at 0.50 mm thickness. In addition, the nanocomposite film exhibits remarkable photothermal responses, reaching 100 °C within 80 s under 100 mW/cm² light exposure. With its outstanding mechanical strength, electrical conductivity, and environmental sustainability, the MS/CNF nanocomposite shows immense potential for applications in wearable electronics, EMI shielding, and thermal therapy, offering a versatile and scalable solution for next-generation electronic and energy-efficient technologies.