Photo-supercapacitors based on zinc oxide/MXene paper dual acting electrodes

Abstract

Photo-supercapacitors (PSCs) have great potential as devices that enable both the conversion and storage of solar energy. However, it remains challenging to design new dual-acting electrodes providing high energy density and capacitance with self-powering capacity. Herein, we successfully prepared dual electrodes using ZnO-nanoflake and Ti3C2Tx-based MXene paper. By utilization of the MXene to the PSC device, capacitive contribution to the total capacitance increased ∼4 times compared to the bare ZnO-nanoflake-based PSC due to the surface redox reactions and electrically double layer formation. Maximum energy and power density of 57.3 μWhcm−2 and 11.1 mWcm−2, respectively were obtained for ZnO/MXene//MXene-PSC@UV irradiation and at a 2.5 V. Areal capacitance of this device calculated from CV was as high as 151.5 mFcm−2. Moreover, the ZnO/MXene//MXene-PSC device was highly stable over 10,000 GCD cycles with 100 % CE and 98 % Cp-retention under daylight.