Nitrogen and oxygen dual-doped activated carbon as electrode material for high performance supercapacitors prepared by direct carbonization of amaranthus

Highlights: • Amaranthus derived N and O dual-doped activated carbons have been prepared. • Carbons were prepared via one step direct carbonization without activation agents. • The preparation process is simple, not costly and low environmental pollution. • Nitric acid treatment can facilitate super-capacitive performance of carbons. • XC-700-50 exhibits high capacitance, good rate capability and cycling stability. -- Abstract: With supercapacitors application promotion, looking for simple, energy efficient and environment-friendly method for expandable production of carbon materials with uniform heteroatoms doping as high-performance electrode materials for supercapacitors becomes the keystone of current research. Here, we present a simple, not costly, low environmental pollution method for preparation of nitrogen and oxygen dual-doped activated carbons via one step direct carbonization of natural, renewable and abundant amaranthus followed by ultrasonic treatment with nitric acid. Most noteworthy is XC-700-50, which exhibits high conductivity, moderate surface area, reasonable pore size distribution and high O and N doping contents (12.05% and 5.31% respectively). Benefiting from these features, it displays high gravimetric capacitance (326 F g⁻¹ and 294 F g⁻¹ at 0.5 A g⁻¹ and 1 A g⁻¹, respectively), good rate capability, as well as excellent cycling stability (about 97.1% and 94.4% of capacitance retention after 10000 cycles at 2 A g⁻¹ and 10 A g⁻¹, respectively) in the high mass loading electrode (8 mg cm⁻²), making it a promising electrode material for supercapacitors.