Supercritical CO₂-assisted deposition of NiO on (101)-anatase-TiO₂ for efficient facet engineered photocatalysts

Abstract

Deposition of NiO on the (101) facet of anatase nanocrystals by the SFCD route yields nanocomposites more efficient than pure anatase TiO2 for the photodecomposition of both anionic and cationic dyes.

Supercritical Carbon Dioxide-Based Processes in Photocatalytic Applications

“…Similarly, Liu et al [ 62 ] and Kashiwaya et al [ 63 ] prepared photocatalysts by supercritical decomposition, to be applied for the photocatalytic removal of two dyes, methylene blue, and methyl orange. In particular, Liu et al [ 62 ] proposed a novel method of “supercritical deposition assisted by liquid-crystal template” to prepare nanocomposites consisting of mesoporous silica SBA-15 coated with TiO 2 .…”

“…Compared to the results obtained by coating the TiO 2 on the surface of non-porous SBA-15 using a similar approach without template, mesoporous TiO 2 coated SBA-15 showed a more uniform deposition and an improved degradation efficiency for azo dyes as well as phenol. In the study of Kashiwaya et al [ 63 ], the scCO 2 allowed to effectively impregnate nitrate nickel oxide (NiO) nanoparticles, starting from hexahydrate (Ni(NO 3 ) 2 6H 2 O) as the organometallic precursor, on the (101)-facet of the oriented TiO 2 nanoparticles. In this way, heterostructure NiO/(101)-anatase-TiO 2 nanoparticles were synthesized, characterized by good dispersion of NiO.…”

Chemistry in supercritical fluids for the synthesis of metal nanomaterials

“…It is particularly suitable to achieve homogeneous and conformal deposition of nanomaterials on substrates with complex topographies and ultrafine microstructures. [60][61][62][63][64][65] The third is 'supercritical microfluidics' which runs supercritical fluid synthesis of nanomaterials in 'on-chip' microsystems with good control on process conditions and high reproducibility. Examples of such advantages in material synthesis are shown in the synthesis of semiconductor nanocrystal quantum dots (QDs) whose optical and electronic properties are primarily dependent on the size and crystallinity.…”

Nickel Oxide Selectively Deposited on the {101} Facet of Anatase TiO2 Nanocrystal Bipyramids for Enhanced Photocatalysis

“…In this context, nickel oxide (NiO), which is rather abundant and reactive, is one of the most investigated cocatalysts in combination with TiO 2 and can act as both reduction and oxidation cocatalysts. Thus, various NiO–TiO 2 nanostructures with a random distribution of NiO onto TiO 2 have been reported which led to improved photocatalytic properties for pollutant degradation − or hydrogen production. ,, However, the selective deposition of NiO onto oriented TiO 2 nanoparticles has never been achieved, and both electronic and photocatalytic properties of the resulting heterostructures have not been investigated yet. Furthermore, even though different energy band alignments at the NiO−TiO 2 interface have been proposed for NiO species randomly distributed onto nanoparticles TiO 2 , ,, the energy band alignment of well-defined NiO–anatase (101) and NiO–anastase (001) interfaces still remains unknown.…”

“…Thus, various NiO–TiO 2 nanostructures with a random distribution of NiO onto TiO 2 have been reported which led to improved photocatalytic properties for pollutant degradation − or hydrogen production. ,, However, the selective deposition of NiO onto oriented TiO 2 nanoparticles has never been achieved, and both electronic and photocatalytic properties of the resulting heterostructures have not been investigated yet. Furthermore, even though different energy band alignments at the NiO−TiO 2 interface have been proposed for NiO species randomly distributed onto nanoparticles TiO 2 , ,, the energy band alignment of well-defined NiO–anatase (101) and NiO–anastase (001) interfaces still remains unknown.…”