Photocatalytic Properties of Co3O4-Coated TiO2 Powders Prepared by Plasma-Enhanced Atomic Layer Deposition

Abstract

Co3O4-coated commercial TiO2 powders (P25) p-n junction photocatalysts were prepared by plasma-enhanced atomic layer deposition (PEALD) technique. The structure, morphology, bandgap, and photocatalytic properties under ultraviolet light were investigated systematically. Although the deposition of Co3O4 does not change the anatase structure and crystallite size of P25 powders, the ultraviolet photocatalytic activity has been improved evidently. For the Co3O4-coated P25 powders, the trace Co ions exist as Co3O4 nanoparticles attached to TiO2 powder surface instead of the occupation of Ti4+ position in TiO2 lattice. The Co3O4-coated P25 powders exhibit enhanced photocatalytic degradation efficiency of almost 100% for methylene blue in 1.5 h under ultraviolet light, compared with P25 of 80%. The Mott-Schottky plots of photocatalyst powders confirm the p-n heterojunction formation in Co3O4–TiO2 nanocomposite materials, which is beneficial to increase the efficiency of photogenerated electron-hole separation. In addition, the Co3O4 coating also promotes the adsorption of organic dyes of methylene blue on P25 powders.

Enhanced visible light photocatalytic activity of Fe2O3 modified TiO2 prepared by atomic layer deposition

“…21–1,272). This result indicates that ultrathin ALD Fe 2 O 3 would not affect the crystal structure of TiO 2 , consistent with our previous finding 24 , 55 . In addition, signals related to Fe 2 O 3 were absent.…”

“…High purity nitrogen gas (N 2 , 99.999%) was used as carrier gas at a total flow rate of 750 sccm and a pressure of 6 hPa in our ALD system (Picosun SUNALE™ R-150B). A particular container with porous mesh was used for ALD coating on powders, which has been reported elsewhere 24,55 , as shown in Fig. 1.…”

Noble‐metal‐free MOF Derived ZnS/CeO2 Decorated with CuS Cocatalyst Photocatalyst with Efficient Photocatalytic Hydrogen Production Character

“…The Mott‐Schottky (MS) plots of ZnS and CeO 2 showed a positive slope, it indicated that the ZnS and CeO 2 were n‐type semiconductor [50] . The flat band potential was derived from the intersection of the tangent line and the x‐coordinate of the curve [51–52] . Flat band potentials of ZnS and CeO 2 were 0.3 V and 0.8 V, and they were −0.06 V and −0.56 V relative to the standard hydrogen electrode (NHE) band potentials.…”

“…[50] The flat band potential was derived from the intersection of the tangent line and the x-coordinate of the curve. [51][52] Flat band potentials of ZnS and CeO 2 were 0.3 V and 0.8 V, and they were À 0.06 V and À 0.56 V relative to the standard hydrogen electrode (NHE) band potentials. The conduction band potential (E CB ) of n-type semiconductor is more negative about 0.1 V than the flat-band potential.…”

Enhanced photocatalytic activity and magnetic properties of CNTs/Sn-doped Co3O4 nanocomposite

“…Co3O4 with cubic normal spinel structure can be expressed as AB2O4 where A and B define the magnetic Co 2+ ions in tetrahedral sites and non-magnetic Co 3+ ions in octahedral sites. Co 2+ ions have a high-spin state (S=3/2) while Co 3+ ions possess a low-spin state (S=0) [13][14][15].…”