Introducing oxygen vacancies on sodium titanate via NaBH4 treatment for conductometric hydrogen gas sensors

Sodium titanate (NTO) has drawn great attentions in various applications, but few works focus on using NTO as gas sensors. The implication of NTO as gas sensors requires a simple synthesis route to fabricate NTO with large surface areas and oxygen vacancies. Herein, Pd-decorated NTO microscale hierarchical spheres (Pd-NTO MHSs) is synthesized using Ti foil as a precursor H2O2 is added to promote the preparation of NTO MHSs under a low base-concentration and low temperature condition, making the synthetic route more eco-friendly than previously methods. Additionally, we demonstrate NaBH4 reduction is a one-step process that simultaneously decorates Pd nanoparticles and brings abundant oxygen vacancies on the NTO surface, but too high NaBH4 concentration deteriorates the hydrogen sensing performance. At the optimized condition, Pd-NTO MHSs have a response time of similar to 1.8 s to 1% H-2 and a wide detection range of 10 ppm to 10% H-2 at 25 degrees C. This study highlights that NaBH4 treatment is an effective strategy for regulating surface chemical properties and introducing oxygen vacancy on NTO, enabling Pd-NTO MHSs an excellent sensing property. It is also helpful for the rational design of NTO as a versatile sensing material with abundant oxygen vacancies to sense other gases.