Integrated hydrogen generation and energy storage using pyrolysis-derived sulfur and nitrogen co-doped carbon from waste biomass

Abstract

In this work, a sustainable dual-functional porous carbon was produced from waste tea leaves through pyrolysisbased activation followed by sulfur-nitrogen co-doping (S/N-TWAC). Structural analyses (TEM, XPS, BET) confirmed successful heteroatom incorporation, nanoscale particle formation, and significant improvements in surface area and porosity. The S/N-TWAC catalyst exhibited excellent activity toward NaBH4 methanolysis, generating H2 rapidly within 8.5 min and achieving an HGR of 9582 mL/min/g, which increased to 18190 mL/ min/g at 50 degrees C (Ea = 27.49 kJ/mol). The catalyst retained over 68 % of its activity after five cycles, demonstrating good durability. In addition, S/N-TWAC served as an efficient supercapacitor (SC) electrode, delivering a threefold capacitance enhancement and 94.8 % retention over 10000 cycles. A symmetric device assembled with this material achieved an energy density of 5.6 Wh/kg at 600 W/kg with 92.6 % cycling stability. Overall, the study highlights the effectiveness of pyrolysis in producing multifunctional biomass-derived carbons and identifies S/N-TWAC as a promising material for both H2 generation and energy storage applications.