Ice‐Templated Undaria Pinnatifida Aerogel‐Derived Porous Carbon for Enhanced Room‐Temperature Hydrazine Sensing

ABSTRACT This study develops a high‐performance room‐temperature (RT) hydrazine (N ₂ H ₄ ) gas sensing material based on sustainable algal biomass. A porous carbon material (US‐1.5) was fabricated from Undaria pinnatifida and sodium alginate via ice‐templating and freeze‐drying, yielding a hierarchical meso/macroporous structure that facilitates gas diffusion. Natural heteroatoms enable in situ self‐doping, modulating electronic structure and surface reactivity. First‐principles calculations confirm S‐doping enhances adsorption energy and promotes charge transfer, creating more active sites for gas‐surface interactions. The resulting US‐1.5 sensing material demonstrates a high response of 22.53k% to 500 ppm N ₂ H ₄ , rapid response/recovery times (21.3 s/2.5 s), a low detection limit of 0.138 ppm, excellent selectivity, and cycling stability. It also shows humidity‐dependent dual‐mode sensing. This work pioneers algal aerogel‐derived sensing materials, demonstrating marine waste upcycling for green, cost‐effective gas sensing in environmental and industrial safety applications.