Synergy of surface sodium and hydroxyl on NaTi2HO5 nanotubes accelerating the Pt-dominated ambient HCHO oxidation.

Abstract

Surface hydroxyl is widely perceived as conducive to HCHO degradation. Here, a kind of sodium titanate with interlayered hydroxyls (NaTi2HO5) was prepared to study the action conditions of surface hydroxyls in HCHO oxidation. The nanotubes mainly exposing (001) and nanobelts mainly exposing (100) are synthesized as the two morphologies of NaTi2HO5. We found the (001) facet is much more favored to HCHO adsorption via HRTEM and XPS analysis. The DFT calculations prove that the synergy of surface hydroxyl and Na atom is perfect for HCHO chemisorption. By this means NaTi2HO5 nanotubes can partially oxidize HCHO into formate and release very few CO, measured by in situ DRIFTS. Dominated by Pt nanoparticles, the complete oxidation of HCHO can be performed on NaTi2HO5 nanotubes with enhanced early reaction speed. Rather than simple surface hydroxyl, the effective synergy of hydroxyl and positive ion is proposed as an advantage for HCHO oxidation.