Nanoporous Activated Carbons Derived from Agro-Waste Corncob for Enhanced Electrochemical and Sensing Performance

Nanoporous activated carbons (AC) have been prepared from low-cost agro-waste corncob powder by phosphoric acid activation and investigated for their electrochemical supercapacitor and sensing properties. Surface areas and pore volumes are found in the range of 690–1288 m2 g−1 and 0.49–1.64 cm3 g−1, respectively and could be controlled by adjusting the weight ratio of corncob and phosphorous. The corncob-derived AC showed excellent electrochemical performance giving a maximum specific capacitance ca. 340.8 F g−1 at a scan rate of 5 mV s−1. At relatively a high scan rate of 100 mV s−1 the specific capacitance of 133.7 F g−1 was obtained. About 96% capacitance retention rate was achieved even after 1000 cycles demonstrating potential usages of the materials in high-performance supercapacitor electrodes. Furthermore, our AC showed excellent solvent vapor sensing performance with high selectivity for ammonia.