Green and scalable synthesis of porous carbon nanosheet-assembled hierarchical architectures for robust capacitive energy harvesting

Abstract Hierarchical carbon architectures offer superb advantages for energy storage, but their general synthesis requires tedious template methods and subsequent activation processes employing highly corrosive potassium hydroxide as the activation agent. Herein, we report a green and scalable production of the nanosheet-assembled hierarchical carbon architecture using potassium citrate as a green activation agent as well as an in-situ template and petroleum asphalt as the precursor. The replacing potassium hydroxide with potassium citrate can not only reduce the adverse impact on environment during the industrially scalable production but also eliminate the necessity of extra templates in traditional strategies. Meanwhile, the employment of petroleum asphalt as the carbon precursor can increase the yield of carbon, thus reducing the cost for constructing such structures. The as-prepared carbon architecture shows large specific surface area and hierarchical porosity. Besides, the porous carbon nanosheet facilitates efficient electrons/ions transfer which permits high-power handling. Because of these structure merits, the porous carbon nanosheet-assembled hierarchical architecture affords outstanding performance in terms of large specific capacitance, extraordinary rate capability, and long cyclic stability. The strategy demonstrated here may open up new possibilities for creating novel carbon nanostructures for energy-related application in cost-effective manners.