LAUSR

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 inter-planar doping of cobalt in δ-MnO2 structure. The as-prepared catalyst shows the bifunctional catalytic activity towards oxygen reduction reaction (ORR) as well as oxygen evolution reaction (OER) in presence and absence of visible light. Under light conditions, δ-MnO2 shows 11.56% increment in bifunctional activity. Moreover, doped MnO2 sample exhibits 19.23% increment in bifunctional activity as compared to pristine δ-MnO2. Upon light irradiation, doped MnO2 cathode electrode can execute 4 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 catalyst for energy storage applications.