Optimization of Electrode Materials Using Nanocarboxylic Polystyrene Promotes Accumulation for Chromium in Zea mays from Water and Soil Contamination

Abstract

Chromium is a multivalent metal with great development in the energy storage field because it can effectively improve the electrochemical performance of the material. However, chromium(VI) is soluble in water and toxic, which causes serious metal pollution in the environment. In addition, nanoplastics are difficult to degrade and easy to accumulate, which is an urgent environmental problem to be solved. Therefore, we choose Zea mays to absorb chromium ions, nanopolystyrene, nanocarboxylic polystyrene, and their complexes, which can coordinate and decompose with various polymers in Z. mays, and produce coordination, conjugation, mixed valence, and adjacent group effects. Due to the above effects, the UV−vis spectrum of the material is blueshifted; the X-ray photoelectron spectroscopy peaks of Cr 2p have a chemical shift; the pore structure is optimized; the graphitization degree is improved; the content of N, O, and Cr in the material increases; and the elements are evenly distributed. The series of optimization processes makes the electrodes exhibit excellent electrochemical performance in both supercapacitors and lithium-ion batteries. At 0.5 A•g −1 , the specific capacitance of the electrode reaches 490 F•g −1 . After 10,000 cycles, its specific capacitance remains at 429.3 F•g −1 , and the Coulombic efficiency is 89.9%. In lithium-ion batteries, the initial discharging capacity of the electrode is 1071.7 mAh•g −1 at 0.05 A•g −1 . After 5000 cycles, its specific capacity can still reach 242 mAh•g −1 at 0.2 A•g −1 , and the Coulombic efficiency is above 95%.

Utilizing Manganese Phase Transition in Bioabsorption Synthesis of MnO@Carbon Composites for Enhanced High-Performance Supercapacitors

“…The resulting composite material, consisting of biochar and molybdenum nitride, was employed as an electrode material for supercapacitors, exhibiting a specific capacity of 344 F·g –1 at a current density of 0.5 A·g –1 in a 2 M KOH electrolyte. Other studies have also investigated the application of the bioabsorption method using aquatic plants to absorb nanoplastics and to facilitate the bioabsorption of heavy metals and nanoplastics for the preparation of electrode materials. − However, existing literature fails to report the specific role of heavy metals in influencing the electrochemical properties during the bioabsorption method’s electrode material preparation, particularly the process of valence change of metal ions within living organisms. Moreover, during high-temperature pyrolysis, the absorption of different metals at varying temperatures leads to the formation of diverse crystal structures, hindering the accurate determination of the optimal crystal structure for efficient electrochemical energy storage.…”