Hierarchically porous carbon nanosheets derived from Bougainvillea petals with “pores-on-surface” structure for ultrahigh performance Zinc-ions hybrid capacitors

•Ultrahigh specific capacity toward Zinc-ions hybrid capacitors.•Ions transfer through special “mesopores on surface”.•Suitable template derived from natural Bougainvillea Petals.•Hierarchically Porous Carbon Nanosheets with high specific surface area and rich defect. Due to the outstanding electrochemical performance, high safety coefficient, controllable reaction system and low production cost, Zinc-ion hybrid capacitors (ZIHCs) is considered as a new generation of promising energy storage technology, which even seem as a suitable choice for Medical application. However, to produce ideal carbon-base cathode material with low cost and high electrochemical performance still face challenge. Here, we report a ZIHCs’ cathode based on Bougainvillea petal-derived porous carbon nanosheets (Carbonized Bougainvillea activated at 850 °C, CB-3-850). CB-3-850 derived from Bougainvillea petals exhibit extremely an ultrahigh discharge capacity of 239.1 mAh g−1 at 0.5 A g−1 (from 0 V to 1.8 V) and an excellent electrochemical stability at 20 A g−1 (90 %, 10,000 cycles). In addition, ultrahigh energy density (213.4 Wh kg−1) and high power density (14.8 kW kg−1) are realized in CB-3-850. Special “pores-on-surface” structure and ultrathin nanosheet-like morphology of CB-3-850 not only provide a high specific surface area that for more Zn2+ and SO42+ absorbed on its surface but also enable ions across the one nanosheet directly to reach other carbon-sheets units, which realize a fast kinetic process of ions storage and higher capacity. The excellent performance of the Zinc-ion capacitor can be also attributed to N and O doping that strongly interacted with Zn2+ during the charge/discharge process. Finally, natural Bougainvillea petal just contains simple non-metal elements like C, N and O, exhibit high biocompatibility.