Stabilizing Single-Atom Pt on Fe₂O₃ Nanosheets by Constructing Oxygen Vacancies for Ultrafast H₂ Sensing

Single-atom catalysts (SACs) hold great promise in highly sensitive and selective gas sensors due to their ultrahigh atomic efficiency and excellent catalytic activity. However, due to the extremely high surface energy of SACs, it is still a huge challenge to synthesize a stable single-atom metal on sensitive materials. Here, we report an atomic layer deposition (ALD) strategy for the elaborate synthesis of single-atom Pt on oxygen vacancy-rich Fe₂O₃ nanosheets (Pt-Fe₂O₃-V_o), which displayed ultrafast and sensitive detection to H₂, achieving the stability of Pt single atoms. Gas-sensing investigation showed that the Pt-Fe₂O₃-V_o materials enabled a significantly enhanced response of 26.5-50 ppm of H₂, which was 17-fold higher than that of pure Fe₂O₃, as well as ultrafast response time (2 s), extremely low detection limit (86 ppb), and improved stability. The experimental and density functional theory (DFT) studies revealed that the abundant oxygen vacancy sites of Fe₂O₃ contributed to stabilizing the Pt atoms via electron transfer. In addition, the stabilized Pt atoms also greatly promote the electron transfer of H₂ molecules to Fe₂O₃, thereby achieving an excellent H₂ sensing performance. This work provides a potential strategy for the development of highly selective and stable chemical sensors.