Tuning the micro- and nano-structure of porous α-Fe2O3 nanosheets for high-efficient hydrogen detection

Hydrogen(H₂), a clean and sustainable energy carrier of high energy density, is key to the low-carbon energy transition. Due to its colorless, odorless and highly flammable properties, safe and efficient H₂ leakage detection is imperative to prevent explosions. Porous α-Fe₂O₃ nanosheets (NSs) were synthesized via microwave-assisted co-precipitation followed by sintering, using graphene oxide as the template. The resulting α-Fe₂O₃ NSs exhibited a hierarchical structure assembled from sub-level α-Fe₂O₃ nanoparticles at 12–43 nm with a mean diameter of 26 nm. Numerous oxygen vacancy defects were formed on the particle surfaces, endowing the α-Fe₂O₃ NSs with outstanding H₂-sensing performance. At 150 °C, the α-Fe₂O₃ sensor showed ultrahigh sensitivity toward H₂, with response values of 63.7 and 17.9 for 50 ppm and 10 ppm H₂, respectively. Furthermore, the porous α-Fe₂O₃ sensor presented excellent selectivity, maintaining responses below 3 for other tested gases at 100 ppm. Compared with other α-Fe₂O₃-based sensors, the porous α-Fe₂O₃ NSs sensor demonstrates enhanced sensitivity, a lower detection limit, and a reduced optimal working temperature. The ultra-sensitive H₂-sensing property of the α-Fe₂O₃ NSs is attributed to the porous architecture, fine-grained substructures and massive oxygen vacancies. These findings highlight the potential of porous α-Fe₂O₃ NSs for high-performance hydrogen detection applications.