Polymer carbon dots from plastics waste upcycling

We present the upcycling of plastic waste into photoluminescence polymer carbon dots (C-Dots). The recycling was conducted to the polypropylene (PP) plastic waste using a simple heating process at around its melting point temperatures of 200 °C, 250 °C, and 300 °C. The optical properties and size as well as structure of polymer C-Dots from PP plastic waste are successfully identified. The newly polymer C-Dots from plastic waste recycling have absorption spectra at the 400–435 nm wavelength range. We obtained a very unique rare phenomenon on the emission spectra that it happened two peaks emission wavelengths of 410 nm (3.03 eV) and 440 (2.83 eV). Polymer C-Dots from PP plastic waste has an average particles size of ∼15 nm (200 °C), ∼11 nm (250 °C) and ∼8 nm (300 °C). The alteration of the optical properties—absorption spectra and emission spectra—as well as particle size of polymer C-Dots are caused by structural change of PP plastic waste due to heating process in recycling process. During the heating process on PP plastic waste, the carbon chain binds oxygen from the environment and forms C=O carbonyl group on the wave number 1638 cm-1 which is the main constituent of Polymer C-Dots. Recycling of PP plastic waste into polymer C-Dots has a huge potential to be used as materials for photocatalyst, bioimaging as well as sensors in optoelectronic materials. Furthermore, the result of this study has a role as real action in term of environmental conservation and it answers how to overcoming the problem of plastic waste

Improving the Structural Ordering and Particle-Size Homogeneity of Li-Rich Layered Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ Cathode Materials through Microwave Irradiation Solid-State Synthesis

Li1.2Ni0.13Co0.13Mn0.54O2 (LNCM) has been intensively investigated owing to its high capacity and large voltage window. However, despite its high performance, the synthesis of LNCM can be challenging as it usually contains structural disorders and particle-size inhomogeneities, especially via a solid-state method. This work introduces microwave irradiation treatment on the LNCM fabricated via a solid-state method. The as-treated LNCM has low structural disorders, as indicated by the smaller cation mixing, better hexagonal ordering, and higher c/a ratio compared to the non-treated LNCM. Furthermore, the particle-size homogeneities of as-treated LNCM improved, as characterized by scanning electron microscopy (SEM) and particle size analyzer (PSA) measurements. The improved structural ordering and particle-size homogeneity of the treated sample enhances the specific capacity, initial Coulombic efficiency, and rate capability of the cathode material. The LNCM sample with 20 min of microwave treatment exhibits an optimum performance, showing a large specific capacity (259.84 mAh/g), a high first-cycle Coulombic efficiency (81.45%), and good rate capability. It also showed a stable electrochemical performance with 80.57% capacity retention after 200 cycles (at a charge/discharge of 0.2C/0.5C), which is 13% higher than samples without microwave irradiation