Photo-assisted charging of carbon fiber paper-supported CeO2/MnO2 heterojunction and its long-lasting capacitance enhancement in dark

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 CeO2/MnO2 composite (CeO2/MnO2-CFP) as a binder-free photo-electrode for the photo-assisted electrochemical charge storage. The formation of CeO2/MnO2 type II heterojunction largely enhanced the separation efficiency of photo-generated charge carriers, resulting in a substantially enhanced photo-assisted charging capability of similar to 20%. Furthermore, it retained a large part of its photo-enhanced capacitance (similar to 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.

Automated summary

Developing green and sustainable approaches to enhance electrochemical charge storage efficiencies is emphasized. In this study, a two-step in-situ growth process was used to fabricate a CeO2/MnO2 composite photo-electrode with enhanced photo-assisted charging capability. The formation of a CeO2/MnO2 heterojunction improved the separation efficiency of photo-generated charge carriers. Additionally, the photo-enhanced capacitance of the photo-electrode was retained even in the dark for a prolonged period.