Photoenhanced performance of Cobalt-intercalated 2-D manganese oxide sheets for rechargeable zinc–air batteries

Abstract

Conversion and storage of renewable energy is an important step towards the sustainable future. In this work, we have combined photoconversion of solar energy and Zn–air batteries in a single device which could be an effective strategy for augmenting energy conversion and storage. We report the synthesis of inexpensive cobalt-doped 2D δ-MnO2 nanosheets by one-pot hydrothermal method. Spectroscopic and microscopic characterizations prove both in-plane and interplanar doping of cobalt in δ-MnO2 structure. The as-prepared catalyst shows the bifunctional catalytic activity toward oxygen reduction reaction as well as oxygen evolution reaction in presence and absence of visible light. Under light conditions, δ-MnO2 shows 11.56% increment in bifunctional activity. Moreover, the doped MnO2 sample exhibits 19.23% increment in bifunctional activity as compared with pristine δ-MnO2. Upon light irradiation, the doped MnO2 cathode electrode can execute four times enhancement in power density, 2.38% improvement in voltage difference between charging and discharging and 16.26% increment in round-trip efficiency. This work provides a simple and easy method to prepare stable and durable photoactive bifunctional catalysts for energy storage applications.