Green conversion of bamboo chips into high-performance phenol adsorbent and supercapacitor electrodes by simultaneous activation and nitrogen doping

•A novel one-step method for the preparation of nitrogen-doped biochar was proposed.•The physicochemical properties of biochar can be adjusted by pyrolysis control.•The adsorption mechanism at the molecular level was revealed.•The adsorption capacity of phenol was 169.5 mg/g, and the specific capacitance was 208 F/g.