Influence of Carbonization Temperature on the Tunable Work Function of Graphite-like Biomass Carbon Derived from...

Graphite electrodes are widely used in electrochemical and energy-related applications; however, their properties are often limited by the natural origin of graphite, restricting tunability. Herein, we present a simple and scalable route to produce graphite-like carbon from Wolffia globosa biomass with tunable structural and electronic properties. This rapidly growing aquatic plant, abundant in Southeast Asia, was selected due to its high biomass yield, short cultivation period, and intrinsic nitrogen- and oxygen-containing composition, enabling in situ heteroatom self-doping during carbonization. The biomass was carbonized under an argon atmosphere at 900-1300 °C, producing samples denoted as W900-W1300. The effects of carbonization temperature on the structural, chemical, and electronic properties were systematically investigated. FTIR analysis showed progressive removal of oxygen-containing functional groups above 1100 °C, indicating recovery of sp² carbon domains. Raman spectroscopy revealed a decrease in the I_D/I_G ratio from 1.320 to 1.000 and an increase in crystallite size from 14.56 to 19.22 nm, confirming enhanced graphitization. XPS results further demonstrated an increase in the sp²/sp³ ratio with increasing temperature. SEM and TEM analyses showed the formation of well-organized nanosheet structures, while BET analysis confirmed enhanced surface area and pore development at higher temperatures. UPS measurements indicated tunable work functions ranging from 2.66 to 4.13 eV. These results demonstrate that Wolffia globosa is a promising renewable precursor for producing graphite-like carbon for energy storage and optoelectronic applications.