A carbon dot-based time-dependent color-changing room temperature phosphorescent material with facile synthesis.

Carbon dots have attracted widespread attention due to their excellent optical properties and so on and are therefore used in various fields such as anti-counterfeiting. There are many reports on carbon dot-based room-temperature phosphorescent materials, but there are still fewer reports on carbon dot-based room-temperature phosphorescent materials with time-dependent color-changing properties. In this work, a time-dependent color-changing carbon dot-based room-temperature phosphorescent material with the ability to change from green to blue was successfully prepared by a simple one-pot heating method using hydroxyurea as the only raw material. In this process, hydroxyurea is used as both a carbon and nitrogen source, and in the process of material formation, hydroxyurea also partially forms cyanuric acid as a matrix to make the carbon dots uniformly dispersed in it. By blending the ratio of the dual emission centers of the carbon dots themselves, the final effect of time-dependent color-changing is achieved by taking advantage of the intensity changes and color differences of each emission center. The present work provides new ideas for the preparation of time-dependent color-changing carbon dot-based room-temperature phosphorescent materials.

Simultaneously realizing enhancement of sensitivity for freshness monitoring and multinomial properties of carrageenan/konjac glucomannan/blueberry anthocyanin-based intelligent film by diatomite.

Here, highly sensitive blueberry anthocyanin (BBA)-induced intelligent indicating films were fabricated by incorporating a novel composite ingredient, diatomite (DA), into a matrix of konjac glucomannan (KGM), carrageenan (CAR) and BBA. We systematically investigated the effects of introducing DA and BBA on the structure, physical properties, colorimetric response, and practical application of the KGM/CAR film. Our findings revealed that the DA particles and BBA were well-distributed in the KGM/CAR matrix through hydrogen bonding interactions. This distribution significantly improved tensile strength, surface hydrophobicity, thermal stability, and barrier properties of the KGM/CAR film. Notably, the KGM/CAR-based intelligent film loaded with 6 % DA exhibited the most optimal properties. Furthermore, DA exhibited a hierarchical porous structure, enabling the KGM/CAR film to detect volatile amines with heightened sensitivity. When applied to monitor shrimp spoilage in transparent plastic packaging, the color of the composite film underwent remarkable changes from bright pink to bluish violet. These color changes correlated well with the total volatile basic nitrogen (TVB-N) and pH changes in the shrimp, as determined by standard laboratory procedures. Our work presents a promising approach to the development of high-performance and intelligent food packaging materials. These materials hold great potential for practical applications in the field of food packaging.

Optimized mesopores enable enhanced capacitance of electrochemical capacitors using ultrahigh surface area carbon derived from waste feathers.

Porous carbons with high specific surface area are critical engineering materials for current electrochemical capacitors (ECs) technology. Controlling the pore size distribution of porous carbons remains a significant challenge as it is a key aspect in many applications. Herein, we synthesized porous carbon as the electrode material of ECs by means of a two-step synthesis procedure using abandoned feathers as carbon precursor and potassium hydroxide as activating agent. The optimal sample (AFHPC-800-1:3) exhibited an ultra-high specific surface area (SBET) of 3474 m2/g and a huge total pore volume (VT) of 1.82 m3 g-1 as well as abundant small mesopores ranging from 2 to 5 nm in size. The ECs based on the AFHPC-800-1:3 electrode exhibited an ultra-high specific capacitance (Csp) of up to 709F g-1 at 0.5 A g-1. More interestingly, a capacitance of 212F g-1 was retained even at 100 A g-1, demonstrating excellent high-rate capacitive performance. Furthermore, the symmetrical capacitor yielded an excellent energy density of 35.1 Wh kg-1 when the specific power density was 625 W kg-1, substantiating the potential of the small mesopores in promoting the overall capacitance and energy density of electrode materials.

One-Pot Synthesis of B/P-Codoped Co-Mo Dual-Nanowafer Electrocatalysts for Overall Water Splitting.

Exploring electrocatalysts with satisfactory activity and durability has remained a long-lasting target for electrolyzing water, which is particularly significant for sustainable hydrogen fuel production. Here, we report a quaternary B/P-codoped transition metal Co-Mo hybrid as an efficient alternative catalyst for overall water splitting. The Co-Mo-B-P/CF dual nanowafers were deposited on a copper foam by double-pulse electrodeposition, which is favorable for achieving a nanocrystalline structure. The Co-Mo-B-P/CF catalyst shows a high catalytic activity along with good long-term stability in 1.0 M KOH solutions for both the hydrogen and oxygen evolution reactions, requiring 48 and 275 mV to reach 10 mA cm-2, respectively. The synergetic effect between Co-Mo and doped B and P elements is mainly attributed to the excellent bifunctional catalysis performance, while the dual-nanowafer structure endows Co-Mo-B-P with numerous catalytical active sites enhancing the utilization efficiency of atoms. Moreover, the catalytic capability of Co-Mo-B-P/CF as a bifunctional electrocatalyst for the overall water splitting is proved, with the current density of 10 mA cm-2 accomplished at 1.59 V. After the stability test for overall water splitting at 1.59 V for 24 h, the activity almost remains unchanged. The features of excellent electrocatalytic activity, simple preparation, and inexpensive raw materials for Co-Mo-B-P/CF as a bifunctional catalyst hold great potentials for overall water splitting.

In situ one-pot synthesis of Sn/lignite-based porous carbon composite for enhanced lithium storage.

To expand the variety of Sn/C composites, lignite-based porous carbon was initially prepared with Baoqing lignite as the raw material and K2CO3 as the extractant and activator. A novel Sn/lignite-based porous carbon composite was subsequently fabricated via an in situ one-pot synthesis method. In the nanocomposite, Sn nanoparticles are uniformly distributed on lignite-based porous carbon, improving the lithium-ion storage performance of the as-prepared material. Compared with pure Sn and bare lignite-based porous carbon, Sn/lignite-based porous carbon displayed a superior electrochemical performance. The composite material exhibits a high reversible capacity of 941 mAh g-1 after 200 cycles at 100 mA g-1. Even after 800 charge/discharge cycles at a high current density of 1000 mA g-1, the nanocomposite retains a reversible capacity of 573 mAh g-1. The enhanced lithium-ion storage performance can be attributed to the combined effect of Sn and lignite-based porous carbon.