Photo-induced self-catalysis of nano-Bi2MoO6 for solar energy harvesting and charge storage

Abstract

Efficient, sustainable, and integrated energy systems require the development of novel multifunctional materials to simultaneously achieve solar energy harvesting and charge storage. Bi-based oxysalt aurivillius phase materials are potential candidates due to their typical photovoltaic effect and their pseudo-capacitance charge storage behavior. Herein, we synthesized nano-Bi₂MoO₆ as a material for both solar energy harvesting and charge storage due to its suitable band gap for absorption of visible light and its well-defined faradaic redox reaction from Bi metal to Bi³⁺. The irradiation of visible light significantly affected the electrochemical processes and the dynamics of the Bi₂MoO₆ electrode. The photo-induced self-catalytic redox mechanism was carefully explored by adding sacrificial agents in photocatalysis reaction. In accordance with the rule of energy matching, the photo-generated holes oxidized the Bi metal to Bi³⁺, and the corresponding peak current increased by 79.5% at a scanning rate of 50 mV s⁻¹. More importantly, the peak current retention rate remained higher than 92.5% during the entire 200 cycles. The photo-generated electrons facilitated a decrease of 184 mV in the overpotential of the reduction process. Furthermore, the irradiation of visible light also accelerated the ionic diffusion of the electrolyte. These investigations provide a unique perspective for the design and development of new multifunctional materials to synergistically realize solar energy harvesting and charge storage.