The thorn-sphere-like WO3 is synthesized through hydrothermal method on the Au-decorated porous silicon (PS) substrates with seed-layer induction.
The morphology of WO3 hierarchical nanostructure depends on the Au-sputtering time and hydrothermal reaction time.
The results show excellent response characteristics at room temperature even to ppb-level NO2.
The hierarchical nanostructure and heterostructure in the sensor play important roles on the enhanced NO2 response.