Highly Efficient Low-Temperature Plasma-Assisted Modification of TiO_2 Nanosheets with Exposed {001} Facets for Enhanced Visible-Light Photocatalytic Activity

摘要

Anatase TiO_2 nanosheets with exposed {001} facets have been controllably modified under non-thermal dielectric barrier discharge (DBD) plasma with various working gas, including Ar, H_2, and NH_3. The obtained TiO_2 nanosheets possess a unique crystalline core/amorphous shell structure (TiO_2@TiO_(2-x)), which exhibit the improved visible and near-infrared light absorption. The types of dopants(oxygen vacancy/surface Ti~(3+)/substituted N) in oxygen-deficient TiO_2 can be tuned by controlling the working gases during plasma discharge. Both surface Ti~(3+) and substituted N were doped into the lattice of TiO_2 through NH_3 plasma discharge, whereas the oxygen vacancy or Ti~(3+) (along with the oxygen vacancy) was obtained after Ar or H_2 plasma treatment. The TiO_2@TiO_(2-x) from NH_3 plasma with a green color shows the highest photocatalytic activity under visiblelight irradiation compared with the products from Ar plasma or H_2 plasma due to the synergistic effect of reduction and simultaneous nitridation in the NH_3 plasma.