Glucose-Derived Carbon Materials via Hydrothermal Carbonization and Pyrolysis for Electrochemical Applications.

Carbon materials are widely used in electrochemical technologies due to their tunable structure and chemical versatility. Hydrothermal carbonization (HTC) of biomass offers a sustainable synthesis route, yet quantitative links between processing conditions and material properties remain unclear. In this study, glucose-derived hydrochars were produced by systematically varying HTC temperature (180-210 °C), residence time (0.5-3 h), and precursor concentration. Increasing reaction severity promoted carbon retention in the solid phase while reducing soluble intermediates. Spectroscopic analyses (FTIR, XPS, Raman) revealed progressive heteroatom removal and development of sp2 carbon domains. Subsequent pyrolysis further enhanced structural ordering and reduced oxygen functionalities without altering morphology. Electrochemical measurements showed stable double-layer capacitance for pristine hydrochars (66 μF cm-2), with moderate improvement after pyrolysis (79 μF cm-2). Oxygen evolution reaction kinetics remained typical of metal-free carbons. Overall, this work establishes clear correlations among HTC conditions, carbon partitioning, structural evolution, and electrochemical behavior, supporting rational design of biomass-derived carbon materials.