Effect of solid inorganic salts on the formation of cubic-like aggregates of ZnSnO3 nanoparticles in solventless, organic-free reactions and their gas sensing behaviors

The effect of added solid inorganic salts on the morphology of ZnSnO3 nanoparticle aggregates has been investigated based on solventless and organic-free reactions at ambient temperature. Cubic-like aggregates of ZnSnO3 nanoparticles can be synthesized successfully through direct reaction of solid MOH (M+ = K+, Na+) with a solid mixture of ZnCl2 and SnCl4·5H2O in the presence of added inorganic salt, MCl (M+ = K+, Na+). In contrast, irregular spherical aggregates of ZnSnO3 nanoparticles are produced in the reactions in absence of added solid inorganic salts. The added solid inorganic salts, which play a key role for producing the cubic-like aggregates of ZnSnO3 nanoparticles with pores of ca. 2.8 nm, may act as a substrate-template for the growth of nanocrystals and the formation of their cubic-like aggregates. Gas sensors are further constructed with the aggregates of ZnSnO3 nanoparticles as sensing materials. The sensors made with the cubic-like aggregates (C-sensors) exhibit much higher responses to the reducing gases tested, compared to those (S-sensors) from spherical aggregates synthesized without adding inorganic substrate-template into the reaction. The approach could open a new pathway for controlling the microstructure of materials with high gas sensing functionality.