New insights into multi-hierarchical nanostructures with size-controllable blocking units for their gas sensing performance

The assembly design of nanostructures has taken a dominated position in improving gas sensing properties. In our work, multi-hierarchical (nanoneedles assembled and nanosheets assembled) SnO2 nanostructures with size-controllable blocking units were synthesized via facile hydrothermal method. As is recorded, the addition of PVP led to the transformation from nanoneedles assembled nanostructures into nanosheets assembled nanostructures, which can be ascribed to linear molecule structures. While the sizes of the blocking units can be controlled by the temperature due to the Ostwald ripening. And seeing from the gas sensing measurement, the thinner ones had higher gas response and quicker gas response and recovery judging from the sizes of blocking units, at the same time, nanoneedles assembled hierarchical structures possessed higher gas response while nanosheets assembled hierarchical structures had shorter gas response and recovery time.