Single-Step Bipolar Exfoliation of Black Phosphorus into Phosphorene for Capacitive Energy Storage Application

Black phosphorus (BP) as a two-dimensional material has attracted attention for various applications from energy storage to biomedical devices due to its exceptional physical and chemical properties such as tunable bandgap and high charge carrier mobility. However, the key step therefore towards the application of BP is the preparation of few-layer phosphorene. Different methods have been evaluated to exfoliate BP such as mechanical, liquid and electrochemical exfoliation. Most of them are multi-step and time-consuming, and less attractive for practical applications. In this study, we propose a novel and straightforward two-in-one bipolar exfoliation technique to exfoliate BP into phosphorene nanosheets in DI water, which are then dragged electrophoretically to be deposited on a conductive substrate. The exfoliated-and-deposited BP nanosheets were characterized with different microscopic and spectroscopic techniques, revealing thin layers of phosphorene with orthorhombic crystal structure and lateral dimensions up to a few hundreds of nanometers. The electrochemical characterization of the phosphorene-modified positive feeding electrode showed a fractional-order capacitive behavior with high power density of 350 μW cm -2 at a constant current rate of 0.5 mA cm -2 and discharge energy of 22.8 nWh cm -2 recoverable with very high efficiency after 40000 of charge/discharge cycles. In this conference, detailed novel bipolar exfoliation and deposition of phosphorene nanosheets and its electrochemical characterization will be presented.