One-Step Thermochemical Conversion of Biomass Waste into Superhydrophobic Carbon Material by Catalytic Pyrolysis

Preparation of superhydrophobic carbon materials from lignocellulosic biomass waste via one-step carbonization is very difficult due to the existences of polar functional groups and ashes, which are extremely hydrophilic. Herein, superhydrophobic carbon materials can be facilely synthesized by catalytic pyrolysis of biomass waste using FeCl₃ as catalyst. The results show that the surface energy of lignin-derived char (Char_L) is significantly reduced to 19.25 mN m^-1 from 73.29 mN m^-1, and the water contact angle increased from 0 to 151.5°, by interaction with FeCl₃. Multiple characterizations and control experiments demonstrate that FeCl₃ can catalyze the pyrolytic volatiles to form a rough graphite and diamond-like carbon layer that isolates the polar functional groups and ashes on Char_L, contributing to the superhydrophobicity of the Char_L. The one-step catalytic pyrolysis is able to convert different natural biomass waste (e.g., lignin, cellulose, sawdust, rice husk, maize straw, and pomelo peel) into superhydrophobic carbon materials. This study contributes new information related to the interfacial chemistry during the sustainable utilization of biomass waste.