Free-Standing Black Phosphorus Foils for Energy Storage and Catalysis

Few-layered black phosphorus (BP) is a two-dimensional material that has attracted intensive attention for applications in energy storage and catalysis due to its large surface area and good electrical and thermal conductivity. Herein, a comparable study of BP electrochemical exfoliation in various solutions of tetrabutylammonium salts (TBAX; X is PF6-, BF4-, and ClO4-) in DMSO is reported. Based on morphological and structural analyses, it is shown that TBAPF(6)/DMSO medium was specifically appropriate for the production of high-quality BP nanosheets with micrometer lateral size and a thickness of about 2.4 nm. TBAPF(6)/DMSO-processed, few-layered BP exhibits enhanced hydrogen evolution reaction (HER) catalytic activity compared with that of samples exfoliated with the assistance of BF4- and ClO4- ions. Finally, the fabrication of flexible, free-standing BP films and their performance in an all-solid-state supercapacitor device are demonstrated.