Synthesis Of Fe₂(MoO₄)₃ Based Composites From Absorbent Cotton Template And Their Gas-sensitive Properties

Fe₂?Mo O₄?₃ with high catalysis and stability has attracted extensive attention in the field of gas sensors in recent years.Up to date,the reported Fe₂?Mo O₄?₃-based H₂S gas sensors still have the disadvantages of low sensitivity,high detection limit,and slow response,which significantly limit their real application.It has been reported that the hierarchical structure of metal oxides can better improve the above shortcomings.However,the corresponding synthetic methods have defects in complex operation,high cost,low yield and environmental pollution.Accordingly,Fe₂?Mo O₄?₃ microtubules and microchains,?-Mo O₃/Fe₂?Mo O₄?₃ and?-Fe₂O₃/Fe₂?Mo O₄?₃ heterostructure microtubules were prepared by simple metal salt impregnation and air calcination method using absorbent cotton as biotemplate,which were further characterized by TG,XRD,SEM,TEM,and BET.Meanwhile,the influence of calcination temperature and doping amount on Fe₂?Mo O₄?₃-based microstructure and gas-sensing properties are discussed,and the gas-sensing mechanism of sensors to H₂S is deeply analyzed by XPS technique.All the Fe₂?Mo O₄?₃-based materials exhibit good sensing performance to H₂S gas.Amongst,the detection limit of single-crystal Fe₂?Mo O₄?₃ microtubules with highly active family of?100?planes is as low as 0.3 ppm,and the two heterogeneous microtubules show excellent gas-sensing performance to H₂S at a relatively low working temperature?133°C?.In particular,the?-Fe₂O₃/Fe₂?Mo O₄?₃ material exhibits the highest sensitivity?12.69?and the fastest response?3 s?to 10 ppm H₂S gas,and the detection limit of 50 ppb is also the lowest among reported Fe₂?Mo O₄?₃-based H₂S sensors.In addition,the above-mentioned sensors exhibit good long-term stability and reproducibility.Therefore,this work will provide a new idea for the synthesis of other binary metal oxide materials using simple biotemplate method.