Thermal treatment versus hydrothermal carbonization: How to synthesize <scp>nitrogen‐enriched</scp> carbon materials for energy storage applications?

The thermal treatment of an activated carbon/chars with a nitrogen precursor is not sustainable nor efficient method for the incorporation N into carbon structure. This study proposes use hydrothermal carbonization (HTC) as environmentally friendly bulk materials. authors propose following sequence synthesis N-enriched materials (NCM) energy storage applications: HTC and biomass → activation N-hydrochar (N-HC). To investigate proposed method, HTCs spent coffee grounds (SCG) precursors (urea alanine) were conducted at 220°C 5 hours. resulted N-HCs subjected to mild via pyrolysis 600°C 2 results showed that enhances matrix many reactions, example, Maillard reaction (MR) or Mannich reaction, which may accompany formation HC solved-intermediate pathway solid-to-solid pathway, respectively. However, adjusting some parameters before HTC, concentration pH value slurry important avoid significant reduction in N-HC yield. led NCM content 10.3wt% X-ray photoelectron spectroscopy (XPS) confirmed increase heterocyclic compounds (pyridinic N, pyrrolic graphitic N) NCM. significantly improved electrochemical properties values specific capacitance electrical conductivity increased by five times four times,