RESUMEN
ZnO is a defect-governed oxide and emits light at both visible and UV regimes. This work employs atomic layer deposition to produce oxide particles on oxygenated carbon nanotubes, and the composites only show emission profiles at short wavelengths. The quenching of defect-related emissions at long wavelengths is verified, owing to carboxyl diffusion into oxygen vacancies, and doping is supported by ZnCO3 formation in oxide lattice. Fully coated tubes display an increased photocurrent and the quantum efficiency increases by 22 % relative to the bare nanotubes.
RESUMEN
The Seebeck coefficient, according to Ioffe's approximation, is inversely proportional to carrier density and decreases with doping. Herein, we find that the incorporation of multi-walled carbon nanotubes into rutile TiO2 improves the electrical conductivity and Seebeck coefficient at a low filling fraction of tubes; moreover, the former was due to the lengthening of the mean free path and doping modified carrier mobility for the latter. Tube-oxide mixing also causes significant phonon drag at the interfaces and the reduced thermal conductivity was verified by the promoted figure of merit.
RESUMEN
Aggregation of carbon nanotubes reduces quantum efficiency and the phenomenon is found to be related to photocurrent leakage through oxygenated lattices acting as low barrier intertube channels. This outcome is supported by calculation and optical excitation experiments.