Biostructure-inspired high entropy carbon-like material derived from Undaria pinnatifida for room-temperature high-sensitivity hydrazine detection

High-entropy carbon materials, a new class of functional materials, leverage multi-component synergy to precisely tune electronic structures and surface reactivity. Inspired by this concept, we developed biostructure-inspired high-entropy-like carbon materials derived from Undaria pinnatifida and applied them to room-temperature gas sensing. Freeze-drying followed by gradient carbonization produced a hierarchical turbinate-like porosity that mimics canine olfaction, while intrinsic multi-element (C/O/Na/Ca/P/S) coordination activated strong gas-surface interactions. DFT calculations confirmed that Ca doping increases hydrazine (N 2 H 4 ) adsorption energy from -0.412 eV to -1.532 eV and charge transfer from 0.039e to 0.070e, and elevates O 2 adsorption energy from -0.160 eV to -1.524 eV with charge transfer rising from 0.181e to 0.790e, validating the dopant's role in boosting surface reactivity. Strategic defect and morphology engineering, coupled with multi-element self-doping, further enriched active sites, enabling the UD-500 to achieve a 14.12k% response to 500 ppm N 2 H 4 at room temperature with a theoretical detection limit of 1.63 ppm, while exhibiting excellent repeatability, long-term stability (<3.5 % drift over 80 days), and humidity tolerance (11-94 % RH). This work establishes a marine-biomass route to high-performance gas sensors and advances the valorization of waste biomass.