Effect of humidity on individual SnO2 coated carbon nanotubes studied by in situ STXM

In situ Scanning Transmission X-ray Microscopy (STXM) with humidity control at the 10ID-1 spectromicroscopy beamline at the Canadian Light Source was used to study the effect of humidity on individual SnO2 coated carbon nanotubes (SnO2/CNT). O 1s STXM image stacks of individual SnO2 coated CNT were measured at controlled relative humidity (RH). At high RH=0.78, 10–50nm of condensed water was found adsorbed on individual SnO2/CNT as determined by spectral curve fitting to O 1s image sequences. Coating variations among individual SnO2/CNT were found. This is consistent with O 1s NEXAFS spectra extracted from the same individual SnO2/CNT. For some entangled SnO2/CNT regions, as much as 200nm condensed liquid water was detected, indicating strong interaction between SnO2 and water.