In situ growth of porous carbon with adjustable morphology on black phosphorus nanosheets for boosting electrocatalytic H2 and O2 evolution

A facile in situ growth method is reported here to prepare black phosphorus nanosheets/porous carbon composites as bifunctional electrocatalysts. Polyvinylpyrrolidone (PVP)-functionalized few-layer black phosphorus nanosheets (PVP–BP) are used as the matrix. With the help of hydrogen bonds and electrostatic interaction, Co, N-codoped porous carbon (PC) with different morphologies can be straightforwardly grown on the surface of PVP–BP. By adding cetyltrimethylammonium bromide (CTAB), PC presents cubic morphology, otherwise, it shows dodecahedron morphology. Both samples, PVP–BP–PC-1 and PVP–BP–PC-2, possess high BET specific surface areas (SSAs) of 1466.7629 m2 g−1 and 1344.6098 m2 g−1, and exhibit excellent electrocatalytic activities. At a current density of 10 mA cm−2, PVP–BP–PC-1 and PVP–BP–PC-2 require the overpotentials of 190 mV and 238.2 mV for hydrogen evolution reaction (HER), respectively, while 433 mV and 430.8 mV for oxygen evolution reaction (OER), respectively. Furthermore, consecutive cyclic voltammetry and chronoamperometric measurements reveal good electrocatalytic stabilities.