Search

According to the United Nations, around 53 million metric tons of electronic waste is produced every year, worldwide, the big majority of which goes unprocessed. With the rapid advances in AI technologies and adoption of smart gadgets, the demand for powerful logic and memory chips is expected to boom. Therefore, the development of green electronics is crucial to minimizing the impact of the alarmingly increasing e‐waste. Here, it is shown the application of a green synthesized, chemically stable, carbonyl‐decorated 2D organic, and biocompatible polymer as an active layer in a memristor device, sandwiched between potentially fully recyclable electrodes. The 2D polymer's ultramicro channels, decorated with C═O and O─H groups, efficiently promote the formation of copper nanofilaments. As a result, the device shows excellent bipolar resistive switching behavior with the potential to mimic synaptic plasticity. A large resistive switching window (103), low SET/RESET voltage of ≈0.5/−1.5 V), excellent device‐to‐device stability and synaptic features are demonstrated. Leveraging the device's synaptic characteristics, its applications in image denoising and edge detection is examined. The results show a reduction in power consumption by a factor of 103 compared to a traditional Tesla P40 graphics processing unit, indicating great promise for future sustainable AI‐based applications. [ABSTRACT FROM AUTHOR]

We report quantitative characterization of the high temperature oxidation process by using electron tomography and energy-dispersive X-ray spectroscopy. As a proof of principle, we performed 3D imaging of the oxidation layer of a model system (Mo3Si) at nanoscale resolution with elemental specificity and probed the oxidation kinetics as a function of the oxidation time and the elevated temperature. Our tomographic reconstructions provide detailed 3D structural information of the surface oxidation layer of the Mo3Si system, revealing the evolution of oxidation behavior of Mo3Si from early stage to mature stage. Based on the relative rate of oxidation of Mo3Si, the volatilization rate of MoO3 and reactive molecular dynamics simulations, we propose a model to explain the mechanism of the formation of the porous silica structure during the oxidation process of Mo3Si. We expect that this 3D quantitative characterization method can be applied to other material systems to probe their structure-property relationships in different environments.

Tomography has made a radical impact on diverse fields ranging from the study of 3D atomic arrangements in matter to the study of human health in medicine. Despite its very diverse applications, the core of tomography remains the same, that is, a mathematical method must be implemented to reconstruct the 3D structure of an object from a number of 2D projections. Here, we present the mathematical implementation of a tomographic algorithm, termed GENeralized Fourier Iterative REconstruction (GENFIRE), for high-resolution 3D reconstruction from a limited number of 2D projections. GENFIRE first assembles a 3D Fourier grid with oversampling and then iterates between real and reciprocal space to search for a global solution that is concurrently consistent with the measured data and general physical constraints. The algorithm requires minimal human intervention and also incorporates angular refinement to reduce the tilt angle error. We demonstrate that GENFIRE can produce superior results relative to several other popular tomographic reconstruction techniques through numerical simulations and by experimentally reconstructing the 3D structure of a porous material and a frozen-hydrated marine cyanobacterium. Equipped with a graphical user interface, GENFIRE is freely available from our website and is expected to find broad applications across different disciplines.

Cobalt is considered an essential element for layered cathode active materials supporting enhanced lithium‐ion conductivity and structural stability. Herein, we investigated the influence of Co concentration on the physicochemical properties and electrochemical performance of lithium‐rich layered oxides (LRLOs) with different Co content (Li1.2Ni0.2‐x/2Mn0.6‐x/2CoxO2, x=0, 0.04, and 0.08). Though the presence of Co grants structural stability to LRLOs, superior long‐term cycling stability is achieved with the Co‐free LRLO retaining 88.1 % of the initial specific capacity (vs. 75.9 % of Li1.2Ni0.16Mn0.56Co0.08O2) after 300 galvanostatic cycles at 250 mA g−1 (1 C). The chemical stability on the surface of LRLOs containing Co declines faster, indicating a higher bulk structural stability not being the primary determinant of the LRLOs' cycling performance. Ex‐situ investigations indicate that the superior cycling stability of Co‐free LRLO is obtained by reducing the Mn‐related redox at discharge, which contributes to the large degree of polarization and low energy efficiency. Finally, the full‐cell configured with the optimized LRLO as cathode and graphite anode delivers an energy density of 464 Wh kg−1 at C/10, and 74.4 % and 94.3 % of retention in discharge specific capacity and average voltage at the 1000th cycle, demonstrating the applicability of Co‐free LRLO for sustainable LIBs. [ABSTRACT FROM AUTHOR]

Zeolites hold importance as catalysts and membranes across numerous industrial processes that produce most of the world's fuels and chemicals. In zeolite catalysis, the rate of molecular diffusion inside the micropore channels defines the catalyst's longevity and selectivity, thereby influencing the catalytic efficiency. Decreasing the diffusion pathlengths of zeolites to the nanoscopic level by fabricating well‐organized hierarchically porous architecture can efficiently overcome their intrinsic mass‐transfer limitations without losing hydrothermal stability. We report a rational post‐synthetic design for synthesizing hierarchically ordered FAU‐type zeolites exhibiting 2D‐hexagonal (P6mm) and 3D‐cubic (Ia3‾ ${\bar{3}}$ d) mesopore channels. The synthesis involves methodical incision of the parent zeolite into unit‐cell level zeolitic fragments by in situ generated base and bulky surfactants. The micellar ensembles formed by these surfactant‐zeolite interactions are subsequently reorganized into various ordered mesophases by tuning the micellar curvature with ion‐specific interactions (Hofmeister effect). Unlike conventional crystallization, which offers poor control over mesophase formation due to kinetic constraints, crystalline mesostructures can be developed under dilute, mild alkaline conditions by controlled reassembly. The prepared zeolites with nanometric diffusion pathlengths have demonstrated excellent yields of naphtha and middle‐distillates in vacuum gas oil hydrocracking with decreased coke deposition. [ABSTRACT FROM AUTHOR]

Sodium‐ion and potassium‐ion batteries (NIBs and KIBs) are considered promising alternatives to replace lithium‐ion batteries (LIBs) in energy storage applications due to the natural abundance and low cost of Na and K. Nevertheless, a critical challenge is that the large size of Na+/K+ leads to a huge volume change of the hosting material during electrochemical cycling, resulting in rapid capacity decay. Among negative candidates for alkali‐metal‐ion batteries, SnS2 is attractive due to the competitively high specific capacity, low redox potential and high abundance. Porous few‐layer SnS2 nanosheets are in situ grown on reduced graphene oxide, forming a SnS2‐rGO sandwich structure via strong C−O−Sn bonds. This nano‐scaled sandwich structure not only shortens Na+/K+ and electron transport pathways but also accommodates volume expansion, thereby enabling high and stable electrochemical cycling performance of SnS2‐rGO. This work explores the influence of different conductive carbons (Super P and C65) on the SnS2‐rGO electrode. In addition, the effects of the electrolyte additive fluoroethylene carbonate (FEC) on the electrochemical performance in NIBs and KIBs is evaluated. This work provides guidelines for optimized electrode structure design, electrolyte additives and carbon additives for the realization of better NIBs and KIBs. [ABSTRACT FROM AUTHOR]

LiNi0.5Mn1.5O4 (LNMO) is a promising cathode in lithium‐ion batteries (LIBs) due to its high operating voltage and open Li+ diffusion framework. However, the instability of the electrode–electrolyte interface and the negative environmental impact of electrode fabrication processes limit its practical application. Therefore, switching electrode processing conditions to aqueous and understanding the accompanying surface structural evolution are imperative. Here, water‐treated, poly(acrylic acid) (PAA)‐treated, and H3PO4‐treated LNMO, labeled as W‐LNMO, A‐LNMO, and H‐LNMO, are studied systematically. W‐LNMO shows a high concentration of Mn3+ induced by Li loss while a conformal PAA layer formed on A‐LNMO reduces this phenomenon. H‐LNMO displays a second MnPO4∙H2O phase. Upon cycling, a fast capacity decay is observed in W‐LNMO while an extra plateau at ≈2.7 V appears in the initial charging, corresponding to a two‐phase transition. A surface reconstruction layer from a spinel to a rock‐salt phase with a reductive Mn2+ segregation is observed in W‐LNMO after 105 cycles. The PAA layer persists on A‐LNMO and alleviates the capacity decay. H‐LNMO delivers a relatively low capacity due to the formation of a MnPO4∙H2O phase. This study provides new insights into manipulating the surface chemistry of LNMO cathodes to enable aqueous, large‐scale processingin LIBs. [ABSTRACT FROM AUTHOR]