Co-pyrolysis of bamboo with low-dose guanidine phosphate to synthesis heteroatom-enriched porous carbon materials for supercapacitors

The conversion of biomass-derived waste into functional carbon materials for application in electrochemical energy storage represents a promising strategy towards green and low-carbon production methods. Incorporating environmentally benign flame retardants as dopants in the co-pyrolysis of biomass to carbon materials offers a novel pathway for fabricating hierarchical porous structures with tailored heteroatom functional groups. This study pioneers a sustainable strategy to convert bamboo waste into heteroatom-doped hierarchical porous carbon for supercapacitors via a two-stage pyrolysis, using eco-friendly nitrogen-phosphorus flame retardants as dual-functional dopants. By integrating guanidine phosphate into bamboo co-pyrolysis (300°C, GP/bamboo ratio 1:2) followed by KHCO₃ activation, the optimal GB12 achieves 387 F/g at 0.5 A/g and 300 F/g at 20 A/g with 77.52 % capacitance retention, outperforming conventional doping methods. Remarkably, low-dose GP doping enables synergistic pore engineering (specific surface area of 1545.8 m²/g) and heteroatom functionality (3.42 % N, 0.49 % P), yielding a symmetric supercapacitor with 8.82 Wh/kg energy density at 125 W/kg. With exceptional electrochemical performance, GB12 demonstrated that low doses of nitrogen-phosphorus flame retardants can achieve remarkable pore formation and heteroatom doping effects. This work redefines flame retardants as efficient carbon activators, establishing a scalable biomass-to-electrode paradigm for advanced energy storage.