Photo-assisted charging of carbon fiber paper-supported CeO2/MnO2 heterojunction and its long-lasting capacitance enhancement in dark
Weiyi Yang, Jian Wang, Shuang Gao, Haoyu Zhang, Hongyang Wang, Qi Li
Abstract
Abstract It is important to develop green and sustainable approaches to enhance electrochemical charge storage efficiencies. Herein, a two-step in-situ growth process was developed to fabricate carbon fiber paper-supported CeO 2 /MnO 2 composite (CeO 2 /MnO 2 —CFP) as a binder-free photo-electrode for the photo-assisted electrochemical charge storage. The formation of CeO 2 /MnO 2 type II heterojunction largely enhanced the separation efficiency of photo-generated charge carriers, resulting in a substantially enhanced photo-assisted charging capability of ∼20%. Furthermore, it retained a large part of its photo-enhanced capacitance (∼56%) in dark even after the illumination was off for 12 h, which could be attributed to its slow release of stored photo-generated electrons from its specific band structure to avoid their reaction with O 2 in dark. This study proposed the design principles for supercapacitors with both the photo-assisted charging capability and its long-lasting retainment in dark, which may be readily applied to other pseudocapacitive materials to better utilize solar energy.