Initial Performance Research Articles

Lithium-rich manganese-based layered oxide cathode materials for lithium-ion batteries modified by MoS2 coatings with two-dimensional graphene-like structures

Lithium-rich manganese-based layered oxide cathode materials (LRMCs) have some unique advantages such as high theoretical capacity (≥ 250 mAh g−1) and high energy density. Therefore, they are deemed as a kind of cathode material for lithium-ion batteries with an excellent prospect of application. However, the redox of oxygen anion is able to generate irreversible lattice oxygen loss, leading to irreversible loss of capacity, bringing about a sharp drop of working voltage, and seriously restricting the commercialization of LRMCs. In this paper, MoS2 coating with two-dimensional graphene-like structure was coated on the surface of LRMCs materials for improving the cycling stability and rate performance. The MoS2 coating can provide a two-dimensional diffusion channel for the migration of lithium-ions, which facilitates the fast release of lithium-ions during cycling process. The results show that the first discharge capacity, initial Coulomb efficiency and rate performance of LRMCs are improved. When the current density is 1 C, the first discharge specific capacity of LRMCs@MoS2 reaches 227.69 mAh g−1, and the capacity retention ratio is 84.98 % after 100 cycles. When the current density is 5 C, it can still provide a discharge specific capacity of 137.87 mAh g−1, demonstrating excellent electrochemical performance. This study comes up a simple and practical idea to realize the modification of cathode materials for high performance lithium-ion batteries.

Exploring MOF-Derived CuO/rGO Heterostructures for Highly Efficient Room Temperature CO2 Sensors.

In response to the urgent need for advanced climate change mitigation tools, this study introduces an innovative CO2 gas sensor based on p-p-type heterostructures designed for effective operation at room temperature. This sensor represents a significant step forward, utilizing the synergistic effects of p-p heterojunctions to enhance the effective interfacial area, thereby improving sensitivity. The incorporation of CuO nanoparticles and rGO sheets also optimizes gas transport channels, enhancing the sensor's performance. Our CuO/rGO heterostructures, with 5 wt % rGO, have shown a notable maximum response of 39.6-500 ppm of CO2 at 25 °C, and a low detection limit of 2 ppm, indicating their potential as high-performance, room-temperature CO2 sensors. The prepared sensor demonstrates long-term stability, maintaining 98% of its initial performance over a 30-day period when tested at 1-day intervals. Additionally, the sensor remains stable under conditions of over 40% relative humidity. Furthermore, a first-principles study provides insights into the interaction mechanisms with CO2 molecules, enhancing our understanding of the sensor's operation. This research contributes to the development of CO2 monitoring solutions, offering a practical and cost-effective approach to environmental monitoring in the context of global climate change efforts.

Did H.M. exhibit accelerated long-term forgetting? Measuring forgetting in amnesia

The early investigations of patient H.M. inaugurated the modern era of memory research. During the 1970s and 1980s, a key debate over whether H.M. with bilateral medial temporal lobe lesions exhibited accelerated long-term forgetting attracted an increasing interest in forgetting research among amnestic patients. Huppert and Piercy (1979) examined H.M.’s performance in visual recognition at 10-minute, 1-day, and 7-day intervals and suggested that H.M. was subjected to rapid forgetting compared with Korsakoff patients and healthy participants reported in Huppert and Piercy (1978). In contrast, Freed et al. (1987) employed the same experimental paradigm and concluded that forgetting rates in H.M. did not differ from those in healthy controls. These incompatible findings highlighted a methodological challenge in measuring forgetting in the cross-group comparison design, where closely equalising the initial performance between patient and control groups is usually suggested. The re-analysis in this viewpoint, using both linear- and nonlinear-based modelling, reconciled the discrepancy between the aforementioned studies. Our results indicated that the rate of forgetting in H.M. did not differ from that in healthy controls, regardless of whether the initial performance was closely matched. Here, we suggest that the cross-group comparisons in forgetting studies do not necessarily seek a perfect match in initial performance unless the risks of confounding encoding and retrieval processes can be effectively controlled.

Enabling Low‐Noise, High‐Detectivity, Stable, and Flexible Perovskite Mesh Nanowire Photodetectors by Phenylethylamine Iodine Doping Strategy

AbstractThe poor stability, high noise, and low detectivity (D*) of perovskite mesh nanowire (PMN) photodetectors (PDs) seriously hinder their practical applications. Here, a phenylethylamine iodine doping strategy (PIDS) is introduced to solve these problems. The PIDS leads to the formation of 2D perovskite PEA2MAx‐1PbxI3x+1 (PEA = phenylethylamine, MA = methylamine) within MAPbI3 PMN, which not only prevents water and oxygen erosion to thwart PMN degradation but also inhibits the transport of dark state carriers to reduce dark current. As a result, the noise, D*, and stability of the PMN PD are simultaneously improved. The device exhibits low noise current (7.61 × 10−15 A Hz−1/2) and high D* of 3.2 × 1014 Jones, the highest D* value for PMN PDs reported to date. Moreover, the unpacked device sustains 100% of its initial performance after 2880 h of storage in the air (45–55% humidity), enabling it as the most stable MAPbI3 perovskite micro/nanostructure PD reported to date. Furthermore, the flexible device with PIDS exhibits comparable performance to that of the rigid device as well as great mechanical stability. Finally, the flexible device with PIDS demonstrates excellent optical imaging capability and a higher precision optical imaging potential than the commercial silicon photodiode S2386.

Reciprocal Associations Between Relative or Absolute Physical Activity, Walking Performance, and Autonomy in Outdoor Mobility Among Older Adults: A 4-Year Follow-Up.

Objectives: To examine the reciprocal associations between walking performance, physical activity (PA), and perceived autonomy in outdoor mobility in 322 older adults. Methods: At baseline and four years later, a 6-min walk test assessed walking performance. A thigh-mounted accelerometer monitored relative PA (acceleration exceeding the individual's preferred walking intensity on the walk test) and absolute MVPA (acceleration exceeding 3 METs) in free-living. Autonomy in outdoor mobility was self-reported using the IPA subscale. Cross-lagged panel model was used for analyses. Results: Higher relative PA at baseline predicted better walking performance four years later and vice versa (p < .05). Baseline MVPA did not predict subsequent walking performance, but better initial walking performance predicted higher subsequent MVPA (p < .001). In both models, only walking performance predicted perceived autonomy at follow-up (p < .05). Discussion: Accumulating enough PA of a sufficient relative intensity can maintain good walking performance, which in turn helps to maintain perceived autonomy in mobility.

Room temperature self-healing and high gas barrier properties of elastomer composites incorporated with liquid metal

Flexible electronic devices require stretchable packaging materials that provide a hermetic seal. However, conventional soft materials often exhibit strong gas permeability, making it difficult to achieve stable operation, which requires films with high deformability, self-healing capability, and gas barrier functionality. In this study, a layer by layer (LBL) method was employed to uniformly coat a controllable thickness of liquid metal (LM) onto a designed and synthesized self-healing thermoplastic polyurethane (TPU) film, successfully developing a stretchable gas barrier film (TPU/LM) with high gas barrier properties. The designed polyurethane film significantly enhanced the adhesion of the liquid metal, effectively preventing leakage. The experimental results show that the water vapor transmission rate (WVTR) of the TPU/LM composite film with a thickness of 40 μm is 4.04g/(m2·day). Compared to the film without LM, the gas barrier performance has been improved by approximately 16 times. Additionally, there is a significant enhancement in nitrogen (N2) barrier, with a permeation rate reaching 4.0*10−17 cm3 cm/(cm2·s·Pa), effectively blocking the N2 permeation. This demonstrates the universality of the TPU/LM in gas barrier applications. Furthermore, the TPU/LM film also demonstrated excellent electromagnetic shielding effectiveness. The self-healing capability of the stretchable gas barrier film allows it to recover its initial gas barrier performance after mechanical damage. Humidity-sensitive resistors encapsulated with TPU/LM exhibited stable operation in both air and 90 % humidity environments, confirming the superior barrier properties of the TPU/LM. Generally, the developed TPU/LM is suitable for packaging applications in the next generation of flexible electronic devices.

PETcoil: first results from a second-generation RF-penetrable TOF-PET brain insert for simultaneous PET/MRI

Simultaneous positron emission tomography (PET)/magnetic resonance imaging provides concurrent information about anatomic, functional, and molecular changes in disease. We are developing a second generation MR-compatible RF-penetrable TOF-PET insert. The insert has a smaller scintillation crystal size and ring diameter compared to clinical whole-body PET scanners, resulting in higher spatial resolution and sensitivity. This paper reports the initial system performance of this full-ring PET insert. The global photopeak energy resolution and global coincidence time resolution, 11.74 ± 0.03 % FWHM and 238.1 ± 0.5 ps FWHM, respectively, are preserved as we scaled up the system to a full ring comprising 12, 288 LYSO-SiPM channels (crystal size: 3.2 × 3.2 × 20 mm3). Throughout a ten-hour experiment, the system performance remained stable, exhibiting a less than 1% change in all measured parameters. In a resolution phantom study, the system successfully resolved all 2.8 mm diameter rods, achieving an average VPR of 0.28 ± 0.08 without TOF and 0.24 ± 0.07 with TOF applied. Moreover, the implementation of TOF in the Hoffman phantom study also enhanced image quality. Initial MR compatibility studies of the full PET ring were performed with it unpowered as a milestone to focus on looking for material and geometry-related artifacts. During all MR studies, the MR body coil functioned as both the transmit and receive coil, and no observable artifacts were detected. As expected, using the body coil also as the RF receiver, MR image signal-to-noise ratio exhibited degradation (∼30%), so we are developing a high quality receive-only coil that resides inside the PET ring.

Overtrust in AI Recommendations About Whether or Not to Kill: Evidence from Two Human-Robot Interaction Studies

This research explores prospective determinants of trust in the recommendations of artificial agents regarding decisions to kill, using a novel visual challenge paradigm simulating threat-identification (enemy combatants vs. civilians) under uncertainty. In Experiment 1, we compared trust in the advice of a physically embodied versus screen-mediated anthropomorphic robot, observing no effects of embodiment; in Experiment 2, we manipulated the relative anthropomorphism of virtual robots, observing modestly greater trust in the most anthropomorphic agent relative to the least. Across studies, when any version of the agent randomly disagreed, participants reversed their threat-identifications and decisions to kill in the majority of cases, substantially degrading their initial performance. Participants’ subjective confidence in their decisions tracked whether the agent (dis)agreed, while both decision-reversals and confidence were moderated by appraisals of the agent’s intelligence. The overall findings indicate a strong propensity to overtrust unreliable AI in life-or-death decisions made under uncertainty.

Different delayed consequences of attaining a plateau phase in practicing a simple (finger-tapping sequence learning) and a complex (Tower of Hanoi puzzle) task.

In practicing a new task, the initial performance gains, across consecutive trials, decrease; in the following phase, performance tends to plateau. However, after a long delay additional performance improvements may emerge (delayed/ "offline" gains). It has been suggested that the attainment of the plateau phase is a necessary condition for the triggering of skill consolidation processes that lead to the expression of delayed gains. Here we compared the effect of a long-delay (24-48h) interval following each of the two within-session phases, on performance in a simple motor task, the finger-tapping sequence learning (FTSL), and in a conceptually complex task, the Tower of Hanoi puzzle (TOHP). In Experiment 1 we determined the amount of practice leading to the plateau phase within a single practice session (long practice), in each task. Experiment 2 consisted of three consecutive sessions with long-delay intervals in between; in the first session, participants underwent a short practice without attaining the plateau phase, but in the next two sessions, participants received long practice, attaining the plateau phase. In the FTSL, short practice resulted in no delayed gains after the long delay, but after 24-48h following long practice, task performance was further improved. In contrast, no delayed gains evolved in the TOHP during the 24- to 48-h delay following long practice. We propose that the attainment of a plateau phase can indicate either the attainment of a comprehensive task solution routine (achievable for simple tasks) or a preservation of work-in-progress task solution routine (complex tasks); performance after a long post-practice interval can differentiate these two states.

Ultrafast One‐Step Synthesis of Garnet‐Type Solid Electrolytes With Modified Surface and Microstructure for Solid‐State Lithium‐Metal Batteries

AbstractGarnet‐type Li6.5La3Zr1.5Ta0.5O12 (LLZTO) solid electrolytes provide the necessary electrochemical stability and ionic conductivity for solid‐state lithium‐metal batteries (SSLMBs). However, their wider application is hindered by their high interfacial resistance with electrodes and a lengthy synthesis process. This study presents the synthesis of densified LLZTO electrolytes using unconventional Li2O and Li2ZrO3 precursors through an ultrafast (≈60 s) Joule heat‐assisted synthesis approach in a single‐step process. The lower sintering temperature of Li2ZrO3 compared to traditional ZrO2 precursor yields LLZTO with larger grains, resulting in enhanced Li+ conductivity (7.0 × 10−4 S cm−1 at 25 °C), reduced electronic conductivity (1.7 × 10−10 S cm−1), and higher density (94.2%). Applying a 52–80 nm Sn:SnF2 coating on the LLZTO surface using a melt‐quenching approach produces a uniform interlayer that chemically converts to Li‐Sn alloy and LiF upon contact with lithium, resulting in a near‐zero interfacial resistance and a critical current density of 4.2 mA cm−2 at 25 °C. The SSLMBs, incorporating Sn:SnF2‐coated LLZTO electrolyte with NMC811 cathode, demonstrate remarkable initial capacity (181.1 mAh g−1) and cycle performance (88.63% capacity retention at 3000th cycle). The results indicate that this approach has the potential to advance the commercial fabrication technology for high‐performance solid electrolytes for SSLMBs.

The effect of polylactic acid ordering on the long-term corrosion protection capacity of biodegradable magnesium alloys

The polylactic acid (PLA) coatings of different crystallinity were prepared on biodegradable Mg-2.2Zn-0.3Ca alloy wires to improve the long-term anti-corrosion properties. The composition characteristics and microstructure of the samples were investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscope (FTIR), wide angle X-ray diffraction (WAXD) and scanning electron microscope (SEM). The corrosion resistance of all samples was investigated by immersion tests and electrochemical techniques in vitro simulated body fluid (SBF). The results indicated heat treatment improved the crystallinity of PLA coating and heated-coating performed protective behaviors in the short and long-term immersion. The corrosion rate of heated samples was lower than that of unheated samples and exhibited superior long term protective effect for Mg alloy wires. The lifetime of heated sample (H2) increased significantly from 33 to 55 days. The initial electrochemical performance of unheated coating was better than heated coating, but it declined more rapidly during the long-term immersion. These results indicated that PLA coating could not ignore the effect of its crystallinity to anti-corrosion ability, and only the suit heat treatment makes PLA coating more ordering and achieves higher corrosion resistance in vitro immersion. Therefore, it has promising potential by controlling effectively the PLA ordering for surgical implant applications.

Data-driven designed low Pt loading PtFeCoNiMnGa nano high entropy alloy with high catalytic activity for Zn-air batteries

Developing low Pt loading and high-activity oxygen electrocatalysts is necessary to promote large-scale fuel cell applications. By data-driven and density functional theory calculations, PtFeCoNiMnGa nano high entropy alloy (HEA) was synthesized through liquid-phase reduction and H2 calcination method and loaded on carbon nano-tube (CNT). Due to high entropy, electronic modulation, and cocktail effects, PtFeCoNiMnGa HEA catalyst shows great catalytic activity in oxygen evolution/reduction reaction (OER/ORR). The PtFeCoNiMnGa/CNT showed a low overpotential of 243 mV for OER, and for ORR a mass activity of 1.12 A mgPt−1 (5.3 times than Pt/C). Moreover, the PtFeCoNiMnGa/CNT showed high durability by maintaining 95 % of its initial performance for up to 50 h. In addition, the zinc-air battery assembled with PtFeCoNiMnGa/CNT as the cathode catalyst had an open-circuit potential of 1.52 V and an energy density of 130.6 mW cm−2, and was able to operate stably for 120 h without any significant degradation.

Interfacial engineering of (Ce,Zr)O2 composite barrier layers for enhancing the durability of solid oxide fuel cells

The dense GdxCe1-xO2 (GDC) barrier layer can't prevent the diffusion of small amounts of Sr through grain boundaries. Recent studies indicate that the (Ce,Zr)O2 composite, placed between GDC and YSZ (Y2O3 stabilized ZrO2) electrolyte, can effectively suppress SrZrO3 formation. In this study, we successfully designed and prepared an anode-supported solid oxide fuel cell (SOFC) with a dense GDC/IDL (interdiffusion layer) composite barrier layer, demonstrates excellent inhibition of elemental diffusion through grain boundaries. Compared with the cell with a single dense GDC barrier layer, the cell with GDC/IDL composite barrier layer exhibits largely improved durability, with a two-fold decreased degradation rate of 2.7 %/kh, operated under constant current density of 400 mA/cm2 at 720 °C. The cell with GDC/IDL barrier layer presents decreased initial performances, with lager Rohm of 0.085 Ω cm2 than 0.075 Ω cm2, and smaller initial Pmax of 0.905 W/cm2 than 1.019 W/cm2 at 750 °C. However, the cell performance surpasses the cell with single GDC barrier after 230 h. Thus, we obtain a new strategy to achieve improved cell durability by sacrificing the cell's initial performance. The in-situ constructed continuous and dense GDC/IDL composite optimizes the electrolyte/cathode interface while maintaining decent electrochemical performance, providing a new horizon to design and prepare high performance and durable SOFCs.

Exercise and Acute Cognitive Enhancement.

Substantial research has explored the effects of a single session of exercise on cognitive performance. Meta-analytic reviews provide summary statistics relative to these effects when the cognitive task is performed while exercising and when performed after exercise. When performed concomitantly the effects of exercise are typically small or negative with the exception of moderate effects for speed of cognitive performance during moderate intensity exercise. When cognitive performance is assessed following the cessation of exercise, the effects are typically positive. When considering the effects following exercise, most studies have focused on executive function and episodic memory as the cognitive outcomes of interest with meta-analyses supporting small-to-moderate benefits. When potential moderators related to exercise parameters or participants characteristics are examined, results suggest that 20 minutes of moderate to vigorous intensity exercise consistently benefits performance with larger effects evident for executive function tasks with higher cognitive demands, for long-term memory tasks when exercise is performed prior to information encoding, and when considering individuals with lower initial cognitive performance levels. These observed benefits are likely due to the impacts acute exercise can have on physiological arousal, brain function, and brain neurotrophic factors. Advancements in our understanding of the potential of a single session of exercise to benefit cognitive performance are important for exercise prescription and to inform chronic exercise programs designed to benefit cognition.

Light-weight flexible symmetric supercapacitors based on magnesium-zinc codoped MnO2 nanostructures on carbon cloth as enhanced-performance binder-free electrodes

Developing advanced flexible supercapacitors with high energy and power density is a critical research goal. One promising approach involves combining manganese dioxide (MnO2) with a three-dimensional carbon substrate. This strategy leads to the creation of supercapacitor electrode materials that exhibit high specific capacitance, stability, and environmental friendliness. However, the challenge lies in addressing the low electrical conductivity of MnO2, which limits the rate of electron transfer. The incorporation of metal ions enhances the conductivity of manganese oxide, resulting in a significant increase in lattice defects. These defects create abundant active sites for energy storage. In this study, we developed flexible electrodes based on magnesium-doped MnO2, zinc-doped MnO2, and magnesium-zinc codoped MnO2 nanostructures deposited on carbon cloth (CC) via a one-step hydrothermal method. The supercapacitive behavior of these electrodes was investigated using CV and GCD measurements. The as-prepared electrodes exhibit good electrical conductivity, and their interconnected network structure, composed of sponge-shaped nanostructure layers, results in a large specific surface area. This network also facilitates efficient pathways for effective electron transport. The optimized Mg-Zn codoped MnO2@CC sample exhibits a high capacitance of 79.9 mF/cm² at 0.7 mA/cm² and good rate performance, reaching around 46.59 mF/cm² up to 1.5 mA/cm² in the three-electrode system. Notably, the areal capacitance values calculated from the CV curves for all Mg-Zn codoped MnO2@CC electrodes surpass those of Mg-doped MnO2@CC and Zn-doped MnO2@CC. A flexible symmetric supercapacitor assembled using the best Mg-Zn codoped MnO2@CC as both positive and negative electrodes and PVA-Na2SO4 gel electrolyte delivers a desirable energy density of 0.196 mWh/cm2 at 2.38 mW/cm2. Furthermore, this fabricated supercapacitor demonstrates a broad voltage window of 2.25 V and remarkable cycling stability, retaining 83 % of its initial performance after 4000 charge-discharge cycles.

Characterization of a Covid-fired urban bike delivery system: The Montreal experience

The Covid-19 pandemic led to a rapid change in consumers' demand for home deliveries and traditional delivery modes were unable to deliver consumers and shops due to the sudden increase in demand. This study investigates the results of a local cargo bike delivery initiative in Montreal, Canada, during the forced closure of non-essential businesses from March to May 2020. The objective of this study is to identify the variables which interacted with the performance of a cargo bike delivery initiative while considering the specific context of the Covid-19 pandemic. To assess such changing conditions, a multilevel linear regression analysis is carried out. This analysis allows to quantify the number of home deliveries while considering the impact of the number of active Covid-19 cases and sociodemographic predictors on the cargo bike initiative. The dataset covers 6,700 deliveries made by cargo bikes in the city of Montreal over 16 weeks. The results show that the presence of advertising and the characteristics of consumers' households, such as a smaller household size and a younger average age are amongst the strongest factors for the success of such initiative. The specific context of the Covid-19 pandemic allowed a better penetration of cargo bikes within the last-mile ecosystem.

Development of working memory, processing speed, and psychosocial functions in patients with pediatric cancer.

Many patients after pediatric cancer suffer from long-term cognitive difficulties. This study investigates the development of cognitive and psychosocial functions between diagnosis and one year after cancer treatment and reveals insight into the association between cognitive and psychosocial development and various risk factors. This retrospective clinical record review included fifty-seven patients, aged 4-16 years, that were examined at the beginning of the cancer treatment (T1) and one year after cancer treatment (T2) to evaluate the development of working memory (WM), processing speed (PS), psychosocial functions, and quality of life (QoL). About half of the patients showed stable/favorable cognitive development (PS 51.9%; WM 41.4%). The other half exhibited a non-favorable cognitive development, with a decrease of performance between T1 and T2. In 51.6-77.4%, psychosocial functions remained stable/increased between T1 and T2 and QoL scores remained stable in 42.9-61.9%. Changes in prosocial behavior correlated with the development of PS (r = 0.472, p = 0.010). Age at T1 predicted PS at T2 (p = 0.020) and sex predicted peer relations at T2 (p = 0.046). About half of the patients showed stable/favorable whereas the other half experiencing non-favorable cognitive development. The observed disparities in initial and subsequent cognitive performances highlight the importance of early individualized patient monitoring and interventions. IMPACT: We investigated the cognitive and psychosocial development of pediatric cancer patients between diagnosis and one year after termination of cancer treatment. About half of the patients showed stable or favorable cognitive development in processing speed and working memory. The other half exhibited a non-favorable cognitive development, with decreasing performance. Baseline working memory and processing speed was negatively correlated with the respective change score. Changes in prosocial behavior were positively correlated with the development of processing speed. Early individualized patient monitoring and intervention is of crucial importance after pediatric cancer and its treatment.

Development of a Machine Learning Model for the Classification of Enterobius vermicularis Egg.

Enterobius vermicularis (pinworm) infections are a significant global health issue, affecting children predominantly in environments like schools and daycares. Traditional diagnosis using the scotch tape technique involves examining E. vermicularis eggs under a microscope. This method is time-consuming and depends heavily on the examiner's expertise. To improve this, convolutional neural networks (CNNs) have been used to automate the detection of pinworm eggs from microscopic images. In our study, we enhanced E. vermicularis egg detection using a CNN benchmarked against leading models. We digitized and augmented 40,000 images of E. vermicularis eggs (class 1) and artifacts (class 0) for comprehensive training, using an 80:20 training-validation and a five-fold cross-validation. The proposed CNN model showed limited initial performance but achieved 90.0% accuracy, precision, recall, and F1-score after data augmentation. It also demonstrated improved stability with an ROC-AUC metric increase from 0.77 to 0.97. Despite its smaller file size, our CNN model performed comparably to larger models. Notably, the Xception model achieved 99.0% accuracy, precision, recall, and F1-score. These findings highlight the effectiveness of data augmentation and advanced CNN architectures in improving diagnostic accuracy and efficiency for E. vermicularis infections.

Flexible all-solid-state asymmetric supercapacitor based on Ti3C2Tx MXene/graphene/carbon nanotubes

As the emerging 2D materials, MXenes have been regarded as promising electrode materials in supercapacitor as power supply for wearable and portable electronic devices due to their metallic conductivity, hydrophilic feature, abundant functional groups, and large theoretical specific surface area etc. The capacity and rate capability of MXene-based electrodes is limited by the sheet restacking, hindering their further development. Herein, Ti3C2Tx MXene/graphene/carbon nanotubes (MXene/graphene/CNTs) flexible film was successfully fabricated by vacuum assisted filtration. Intercalation and confinement of graphene and carbon nanotubes between the Ti3C2Tx MXene nanosheets could increase the spacing and specific surface area, alleviate the stacking of MXene nanosheets, thus enhancing the electrochemical properties. The prepared MXene/graphene/CNTs film possesses increased specific surface area, average pore size, pore volume (112.259 m2g−1, 9.982 nm, 0.276 cm3g−1), compared to MXene (93.088 m2g−1, 3.786 nm, 0.088 cm3g−1). Consequently, MXene/graphene/CNTs delivers high area specific capacitance of 1862.5 mF cm−2 at 1 mA cm−2 and excellent rate capability (1525 mF cm−2, 81.88 % at 20 mA cm−2). Flexible asymmetric supercapacitor constructed with MXene/graphene/CNTs film and active carbon as positive and negative electrodes, and PVA/H2SO4 gel as solid electrolyte, achieves an energy density of 133.75 μWh cm−2 at the power density of 750 μW cm−2. In addition, there is still 94.9 % of the initial performance after cycling 8000 charge/discharge cycles at 10 mA cm−2, corresponding to a single-turn decay rate down to 0.00019 %. Besides, this flexible supercapacitor manifests outstanding electrochemical stability at different bending times. These advantages make the flexible supercapacitor device very promising for wearable electronics applications.

Making a benign buried bottom interface for high-performance perovskite photovoltaics with a chelating molecule

Interfacial modifications can significantly enhance the photovoltaic performance of perovskite solar cells (PSCs). We introduced an auxiliary chelating agent, 5,6-isopropyridine-L-ascorbic acid (ILAA), to modify the SnO2/perovskite buried interface. By a non-destructive peeling process using a UV epoxy glue, we exposed the buried bottom of the perovskite layer for direct examination. ILAA not only suppressed SnO2 defects and hydroxyl oxygen but also prevented deterioration of the buried bottom of the perovskite layer. Theoretical calculations also confirmed the greater competitiveness of ILAA in interacting with perovskite molecules than dimethyl sulfoxide. The introduction of ILAA optimized the energy band structure of the SnO2-perovskite interface, therefore enhanced the built-in electric field and facilitated efficient charge transfer. Consequently, ILAA-modified PSCs achieved power conversion efficiencies of 24.04 % and 19.10 % for microdevices (0.09 cm2) and modules (19.32 cm2), respectively. These unencapsulated devices exhibited excellent humidity and thermal stability, maintaining over 80 % of their initial performances after being aged in air for 1000 h or continuously heated for 500 h.