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

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.