Kai Qi,Zhenzhen Jin,Dan Wang,Zhenyu Chen,Xingpeng Guo,Yubing Qiu
The degradation of electrochemical activity is the inevitable and noticeable issue in the widespread applications of conducting polypyrrole (PPy), which involves chemical and electrochemical reactions in PPy natural degradation processes. Based on thorough insights into PPy degradation behavior, this work develops a method of theoretical derivation for the natural degradation kinetics model of PPy, which is verified in NaOH aqueous electrolytes and could be further generalized in other media. The kinetics model derives the rate equations of the chemical and electrochemical processes ( v c and v e ) in PPy degradation. The relationships of the electroactivity degradation rate constant ( k deg ) and rate constants of the chemical and electrochemical processes ( k c and k e ) as well as reaction orders of PPy n+ and OH − are established through theoretical deduction. The effects of doping anions in PPy, film thickness, and electrolyte temperature on the degradation kinetics are investigated through theoretical considerations and experimental findings. The degradation level and service failure time of PPy can be effectively predicted using the kinetics model. Establishing the degradation kinetics model would signal the new perspective and depth in comprehensive studies of PPy degradation, finally facilitating the optimization of performance management in PPy practical applications.
Ti3C2Tx MXene has a high specific surface area and high conductivity, and can be used in the field of humidity sensing. By controlling the surface termination and microstructure of the material, it is expected to improve the humidity sensing performance of Ti3C2Tx MXene. In this paper, we report a method of electrolytic intercalation treatment of Ti3C2Tx MXene in NaOH solution. Theoretical and experimental results show that this method can remove the original F terminations from the surface of Ti3C2Tx MXene and form a large number of OH and O terminations. The partial oxidation of the surface and the replacement of terminations and the insertion of Na+ lead to the change of the Ti3C2Tx MXene layer morphology from flat to curly and significantly improve the hydrophilicity and resistance. The curly flake structure constructs a fast channel for the entry and exit of water molecules which improves the hydration/dehydration efficiency of the material; the enhanced hydrophilicity of the material sharply reduces the resistance of the material after moisture absorption, which significantly improves the responsiveness of Ti3C2Tx MXene to humidity. The curly flake Ti3C2Tx MXene humidity sensor has an ultra-high sensitivity of S = 1.2 × 105 (two orders of magnitude higher than that of the reported humidity sensor based on MXene), with a fast response rate (2 s), good repeatability and stability (4 weeks), and it can be used for the analysis of human respiration rate, and also for non-contact sensing detection of the human body and environmental humidity detection.
Shi-yu Feng,Kai Li,Zhu-yu Li,Dong-hong Nan,Yan-qin Huang,Ji Liu,Qiang Lu
A green way for the sustainable utilization of waste polycarbonate (PC) was developed, i.e., NaOH solution-assisted pyrolysis to co-produce phenolic compounds and supercapacitor material. A lab-scale setup was employed for the pyrolysis of PC to explore the regulation effects of NaOH concentration and pyrolytic temperature on the production of phenol and 4-isopropenylphenol (IPP). The yields of phenol and IPP were up to 35.3 wt% and 29.9 wt% at 600 °C and NaOH concentration of 0.5 mol/L, which were much higher than those from pure PC pyrolysis (7.2 wt% and 3.6 wt%). Furthermore, the pyrolytic solid residue was directly subjected to the high-temperature activation to prepare activated carbon, which could be used as a supercapacitor material with an outstanding specific gravimetric capacitance of 182.1 F/g at 1 A/g.
危险品化学品经营许可证（带存储）