Biomorphic synthesis of 3D mesoporous SnO2 with substantially increased gas-sensing performance at room temperature using a simple one-pot hydrothermal method

•The mesoporous biomorphic SnO2 copy the structure of the bio-template.•BCS-450 with more 6 nm pores and more active sites, making NO2 gas easily passed.•BCS-450 can be a good candidate as a key green material for NO2 sensor at RT.•This work made good use of biomass carbon from nature.