Pressure difference-induced synthesis of P-doped carbon nanobowls for high-performance supercapacitors

Abstract Young-Laplace equation and Kelvin equation, as two important and foundational laws in interface physico-chemistry, can reasonably interpret many complicated physico-chemical phenomena at interfaces and have been widely applied to many practical problems arisen from the production and humankind activities. In this work, by means of the large pressure difference generated on a curved surface of nano-sized liquid under the action of surface tension, the transformations from the hollow carbon nanospheres to the carbon nanobowls and the phosphorus-doped carbon nanobowls have been successfully achieved. Compared with the hollow carbon nanospheres, the carbon nanobowls and phosphorus-doped carbon nanobowls possess high packing densities, which are beneficial to form a favorable conductive pathway, leading to enhanced electrochemical performance. In particular, the phosphorus-doped carbon nanobowls, as electrode material for supercapacitors, show a high specific capacitance of 246.22 F cm−3 (273.58 F g−1) and can maintain the capacitance at a high current density of 10 A g−1 without noticeable decay over 40,000 cycles. More importantly, the symmetric supercapacitor based on the phosphorus-doped carbon nanobowls exhibits high energy density and power density as well as excellent cycling stability. This work widens the application of Young-Laplace equation in bowl-like materials and offers new insights into the formation mechanism.