A Single Energy Conversion and Storage Device of Cobalt Oxide Nanosheets and N-Doped Reduced Graphene Oxide Aerogel

摘要

The hybridization between energy conversion and energy storage materials in a single cell (HECS) is proposed in this work. The HECS cell consists of photoactive cobalt oxide (Co_3O_4) positive electrode as the energy conversion material and N-doped reduced graphene oxide aerogel (N-rGO_(AE)) as the energy storage material. The photoactive Co_3O_4 nanosheets were prepared by using various calcination temperatures for which the in situ electrochemical XAS suggests that the Co_3O_4 nanosheets calcined at 300°C exhibit the highest change in oxidation state compared to other conditions. The HECS cell using photoactive Co_3O_4 film calcined at 300°C and N-rGO_(AE) exhibits 1.7-fold higher specific capacitance under LED light illumination than that of the dark condition. Under white LED light illumination, the photovoltaic effect can be generated in the Co_3O_4 electrode with electron-hole pairs, while the N-rGO_(AE) can balance all the charges generated from the Co_3O_4 via both electrochemical double-layer and pseudocapacitive behaviours.