Li Yanyan,Yin Mingying,Yan Ying,Wang Ce,Liu Xincai,Chao Danming
Electrochromic materials have attracted much attention due to their potential in intelligent applications. We report here the preparation of a crosslinked electrochromic polyurea containing oligoanilines and silicon groups (PUOSi), which shows good thermostability and interesting spectral properties. The crosslinked network structure (c-PUOSi) could be accomplished easily by virtue of hydrolysis reaction. The reversible electrochemical activity and improved electrochromic behavior have been disclosed through multiple electrochemical techniques coupled with UV-Vis spectroscopy. The stability of c-PUOSi film in the electrochemical switching measurements has been effectively enhanced through the crosslinking reaction of triethoxysilane end groups, whilst the resulting densified electroactive film shows low response speed during the electrochemical process. Our demonstrated system presents a deep understanding of structure-function relationship, which is a vital implication for the fabrication and application of the electrochromic devices.
Qin’e Zhang,An’an Zhou,Jingjing Wang,Jifeng Wu,Hua Bai
Polyaniline/graphene (PANI/graphene) composites are the most investigated electrode materials for supercapacitors, owing to their high specific capacitance and excellent rate performance. However, a specific capacitance larger than the theoretical limit of the composite has been frequently reported for PANI/graphene composites, and the reason for this over-high capacitance has not been understood. In this work, after systematically investigating the evolution of the electrochemical and spectral properties of PANI/graphene, we prove that the hydroxyl- or amino-terminated oligoanilines generated from degradation of PANI possess a large specific capacitance (>1000 F g−1), and they significantly increase the total specific capacitance of the composite electrode. Graphene in the composite serves as a conductive matrix for electron transport between the low-conductivity hydroxyl or amino-terminated oligoanilines and the current collector. Based on the above results, we put forward a suggestion for simultaneously improving the specific capacitance and cycling stability of the PANI/graphene composites. A PANI/reduced graphene oxide composite material with a specific capacitance of 719 F g−1 at 1.4 A g−1 and 91.3% capacitance retention after 10 000 cycles is obtained.
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