Metal-organic framework derived cobalt and iron oxide nanosheets for ppb-concentration and highly selective hydrogen sulfide sensing

Hydrogen sulfide (H 2 S) sensing with ppb concentration detection limit and high selectivity is highly desired in future exhaled diagnoses of halitosis, asthma and down syndrome, however, needs further developing. Here, a ppb-concentration and highly selective H 2 S sensing has been developed with the two-dimensional cobalt and iron oxide nanosheets (CoFe x O y NSTs), which is transformed from leaf-shaped zeolitic imidazolate frameworks {ZIF-L(Co)} by combined Fe 2+ ion-etching and annealing. Typically, as-prepared CoFe x O y NSTs are of ∼ 10 nm thick with rough surface. Beneficially, the CoFe x O y NSTs present outstanding selectivity to H 2 S against other interfering gases and exhibit a detection limit as low as 50 ppb. Remarkably, the sensor prototypes exhibit a high response to 10 ppm H 2 S (R a /R g  = 23.8) and shows fast response speed (∼13 s to 10 ppm H 2 S). Theoretically, such excellent H 2 S sensing might be attributed to the high surface ratio of CoFe x O y NSTs providing enriched adsorption sites for H 2 S molecules. Practically, an H 2 S sensing device built with the CoFe x O y NSTs sensor prototype is simulated for detecting H 2 S with reliable response, which is potential in future intelligent healthcare.