Facile Synthesis of Two-Dimensional (2D) Boron Carbonitride and 2D Porous Boron Carbonitride for Excellent Energy Storage and Gas Adsorption Applications

The development of two-dimensional (2D) carbon nanosheets and microporous 2D carbon nanosheets with high specific surface area (SSA), large pore volume, and high conductivity is important for energy storage and gas storage applications. Traditional microporous carbon materials have several disadvantages such as low accessibility of active sites and poor mass transport due to large diffusion pathways. The nanometer-thick 2D microporous carbon nanosheets permit easy mass/heat transport, leading to overcoming the drawbacks of bulk porous materials. Herein, we demonstrate a facile synthesis of 2D boron carbonitride (BCN) and 2D porous BCN for energy and gas storage applications. The 2D BCN sample showed excellent supercapacitor (SC) applications with a specific capacitance (Cs) of 273 F g(-1) under 1 A g-1. Most importantly, 2D porous BCN (p-BCN) was prepared by KOH activation at high temperatures. The optimized 2D porous BCN with highly concentrated micropores and a considerable amount of mesopores provides a high SSA (3310.4 m(2) g(-1)) and pore volume of 1.75 cc g(-1). The combined effect of unique porous nanosheets and optimum doping of heteroatoms allows easy electrolyte/ion diffusion, electron conduction, faradic reactions, and so forth. The p-BCN-800 electrode showed superior Cs of 406 and 355 F g(-1) under 1 A g(-1) in H2SO4 and KOH electrolytes, respectively. Moreover, the symmetric pBCN-800//p-BCN-800 device showed high energy and power densities (17 W h Kg(-1) and 4000 W kg(-1)) with high cycling stability. The 2D porous BCN showed excellent H-2 and CO2 adsorption capacity. The H-2 uptake of 2D porous BCN is 2.91 wt % at 77 K under 1 bar pressure, whereas the CO2 uptake is 3.96 and 2.39 mmol g(-1) at 0 and 25 degrees C, respectively. This work demonstrates an efficient way to produce 2D BCN and 2D porous BCN for energy storage and gas uptake applications.