Supplementary document for Designer Graphene oxide ultrathin flat lens with versatile focusing property - 6839401.pdf

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Supplementary document for Designer Graphene oxide ultrathin flat lens with versatile focusing property - 6678339.pdf

Supplementary Figures and Table

Two-Step Design of a Single-Doped White Phosphor with High Color Rendering

A strategy to design step by step an inorganic single-doped white phosphor is demonstrated. The method consists in tuning different contributions of the emission by successively controlling the chemical compositions of the solid solution or nanosegregated host matrix and the oxidation states of the single dopant. We use this approach to design a white phosphor Na₄CaMgSc₄Si₁₀O₃₀:Eu with excellent color rendering (CRI > 90) that is similar to common mixed-phosphor light sources but for a single-phase. We show that this methodology can also be extended to other phosphors for use in diverse applications such as biomedicine or telecommunications

Pattern Investigation and Quantitative Analysis of Lithium Plating under Subzero Operation of Lithium-Ion Batteries

Safety hazards arising from lithium (Li) plating during the operation of lithium-ion batteries (LIBs) are a constant concern. Herein, this work explores the coaction of low temperatures and current rates (C rates) on Li plating in LIBs by electrochemical tests, material characterization, and numerical analysis. With a decrease in temperature and an increase in C rate, the battery charging process shifts from normal intercalation to Li plating and even ultimately fails at −20 °C and 0.5C. The morphology observations reveal the detailed growth process of individual plated Li through sand-like Li, whisker Li, dendritic Li, mossy Li, and finally bulk Li, as well as aggregated Li from sparse to dense. Through quantitative analysis, the dynamic pattern under long-term cycles is revealed. The low temperature and high C rate will lead to an increase in Li plating capacity and irreversibility, which are further deteriorated with the cycles. In addition, a critical condition of high Li plating and high reversibility at −10 °C and 0.2C is found, and further studies are needed to reveal the competition between kinetics and thermodynamics in the Li plating process. This work provides detailed information on the range and growth process of Li plating and quantifies Li plating, which can be used for practical Li plating prediction and regulation

Pattern Investigation and Quantitative Analysis of Lithium Plating under Subzero Operation of Lithium-Ion Batteries

Safety hazards arising from lithium (Li) plating during the operation of lithium-ion batteries (LIBs) are a constant concern. Herein, this work explores the coaction of low temperatures and current rates (C rates) on Li plating in LIBs by electrochemical tests, material characterization, and numerical analysis. With a decrease in temperature and an increase in C rate, the battery charging process shifts from normal intercalation to Li plating and even ultimately fails at −20 °C and 0.5C. The morphology observations reveal the detailed growth process of individual plated Li through sand-like Li, whisker Li, dendritic Li, mossy Li, and finally bulk Li, as well as aggregated Li from sparse to dense. Through quantitative analysis, the dynamic pattern under long-term cycles is revealed. The low temperature and high C rate will lead to an increase in Li plating capacity and irreversibility, which are further deteriorated with the cycles. In addition, a critical condition of high Li plating and high reversibility at −10 °C and 0.2C is found, and further studies are needed to reveal the competition between kinetics and thermodynamics in the Li plating process. This work provides detailed information on the range and growth process of Li plating and quantifies Li plating, which can be used for practical Li plating prediction and regulation

Improving the Fire Performance of Nylon 6,6 Fabric by Chemical Grafting with Acrylamide

Our previous study has demonstrated that photografting can enhance the flame retardancy of both polyamide and polyester fabric. In this work, efforts to use chemical grafting with acrylamide (AM) as the monomer and dibenzoyl peroxide (BPO) as the initiator were made to improve the homogeneity of the grafting chains and the flame retardancy of nylon 6,6 fabric. The effects of reaction time, reaction temperature, and monomer concentration on the percentage of grafting (PG) were investigated. The effect of PG on the fire performance of AM-<i>g</i>-nylon 6,6 fabric was also studied. The flame retardancy and thermal behavior were characterized in terms of the limiting oxygen index (LOI), UL 94 test, cone calorimetry, thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The results showed that the after-flame time and char length were significantly reduced after grafting. The heat release rate (HRR) of grafted sample was decreased by 28% compared to that of the ungrafted sample. The optimal grafting conditions were obtained as follows: reaction time, 1.5 h; reaction temperature, 70 °C; and concentration of total monomer, 15 wt %. The chemical structure and microstructure of AM-<i>g</i>-nylon 6,6 fabric were analyzed by attenuated-total-reflection Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM), respectively. A possible grafting mechanism is proposed and discussed

Modulation of Defects in Semiconductors by Facile and Controllable Reduction: The Case of p‑type CuCrO₂ Nanoparticles

Optical and electrical characteristics of solid materials are well-known to be intimately related to the presence of intrinsic or extrinsic defects. Hence, the control of defects in semiconductors is of great importance to achieve specific properties, for example, transparency and conductivity. Herein, a facile and controllable reduction method for modulating the defects is proposed and used for the case of p-type delafossite CuCrO₂ nanoparticles. The optical absorption in the infrared region of the CuCrO₂ material can then be fine-tuned via the continuous reduction of nonstoichiometric Cu^II, naturally stabilized in small amounts. This reduction modifies the concentration of positive charge carriers in the material, and thus the conductive and reflective properties, as well as the flat band potential. Indeed, this controllable reduction methodology provides a novel strategy to modulate the (opto-) electronic characteristics of semiconductors

Curvature‐induced Zn 3d electron return on Zn‐N₄ single‐atom carbon nanofibers for boosting electroreduction of CO₂

The electrochemical CO2 reduction to desired chemical feedstocks is of importance, yet it is still challenging to obtain high production selectivity with low overpotential at a current density surpassing the industry benchmark of 100 mA cm‐2. Herein, we constructed a low‐cost Zn single‐atom anchored on curved N‐doped carbon nanofibers (Zn SAs/N‐C) by a facile noncovalent self‐assembly approach. At a low overpotential of only 330 mV, the Zn SAs/N‐C exhibited simultaneously both a high current density up to 121.5 mA cm‐2 and a CO FE of 94.7%, superior to the previous reports. Experiments and DFT calculations revealed that the Zn atoms in Zn‐N4 acted as the active sites, while adjacent pyridine‐N coupled with Zn‐N4 could synergistically decrease the free energy barrier for intermediate *COOH formation. Importantly, the curvature of catalyst induced Zn 3d electrons that were bound to the Zn‐N bonds to return to Zn atom, thereby leading to an increase in electron density of Zn and accelerating CO2 electroreduction to CO

Sulfonation modification of halloysite nanotubes for the in-situ synthesis of polybenzimidazole-based composite proton exchange membranes in wide-temperature range applications

Phosphoric acid-doped polybenzimidazole (PA–PBI) membranes face challenges, such as the easy loss of free PA and the reduced mechanical strength caused by the “plasticization effect” of PA, limiting their application in a wide temperature range. In this study, sulfonated halloysite (sHNT) was used to modify poly(2,5-benzimidazole) (ABPBI) for the in-situ synthesis of a composite proton exchange membrane. The introduction of halloysites in the composite membrane enabled the capturing of PA and water, while its nanoporous structure provided additional paths for proton conduction. Sulfonation modification of halloysite improved the interfacial compatibility between the inorganic particles and the polymer matrix, with the –SO3H groups providing extra proton hopping sites. Due to the well-constructed interface, the resulting sHNT/ABPBI composite membrane exhibited high mechanical strength and excellent proton conductivity across a wide temperature range. The 3 % sHNT/ABPBI composite membrane exhibited a breaking strength of approximately 130 MPa, which was 1.6 times that of pure ABPBI. Moreover, the proton conductivity of the composite exceeded 0.01 S cm−1 at temperatures ranging from 40 to 180 °C. At 160 °C, the peak power density of the PA-doped 3 % sHNT/ABPBI composite membrane was 0.212 W cm−2, which was 1.33 times higher than that of the pure ABPBI membrane. These results show that the composite membrane has potential applications in a wide temperature range.</p