Some Observations on the Development of Superior Photocatalytic Systems for Application to Water Purification by the “Adsorb and Shuttle” or the Interphase Charge Transfer Mechanisms

Abstract

Adsorb and shuttle (A/S) and interfacial charge transfer are the two major strategies for overcoming recombination in photocatalysis in this era of nanoparticle composites. Their relationships are considered here. A review of key literature is accompanied by a presentation of three new experiments within the overall aim of assessing the relation of these strategies. The cases presented include: A/S by a high silica zeolite/TiO2 composite, charge transfer (CT) between phases in a TiO2/WO3 composite and both A/S and CT by composites of TiO2 with powered activated carbon (AC) and single-walled carbon nanotubes (SWCNT). The opportunities presented by the two strategies for moving toward photocatalysts that could support applications for the removal of contaminants from OPEN ACCESSMolecules 2014, 19 19558 drinking water or that lead to a practical adsorbent for organics that could be regenerated photocatalytically link this discussion to ongoing research here.

Study on Simultaneous Removal of Dye and Heavy Metal Ions by NiAl-Layered Double Hydroxide Films

“…The adsorbed MO on the deposition film side could also be degraded by photogenerated charges, which transported through conductive cloth. 36 The synergistic effect of adsorption and photocatalysis on NiAl-LDH composite films facilitated the degradation of MO, which resulted in the highest photocatalytic activity for NiAl-LDH composite films. In addition, after soaking in deionized water or MO solution for a month, NiAl-LDH composite films were not peeled off from the substrate, indicating a strong binding force between the film and substrate.…”

Impact of support characteristics and preparation method on photocatalytic activity of TiO 2 /ZSM-5/silica gel composite photocatalyst

“…After irradiation, increasing the ZSM-5 loading to 0.5 g l −1 led to an increase in the degradation rate of phenol. This was facilitated by the proximity of phenol molecules to TiO 2 , consequently making the phenol molecules easily reachable to the active sites on the TiO 2 surface [ 7 ]. Increasing the ZSM-5 over 0.5 g l −1 has an insignificant effect on phenol degradation.…”

“…If binding is weak, the adsorbed pollutants diffuse between the adsorptive sites and the photocatalytic sites leading to its degradation. This mechanism is known as ‘adsorb and shuttle’ [ 4 – 7 ]. In addition, the composition of an adsorbent and a photocatalyst enables the degradation of low or non-polar pollutants which are poorly degraded due to their very limited adsorption on the polar TiO 2 surface [ 4 ].…”

“…In addition, the composition of an adsorbent and a photocatalyst enables the degradation of low or non-polar pollutants which are poorly degraded due to their very limited adsorption on the polar TiO 2 surface [4]. The composite photocatalyst also reduces the release of intermediates which continue to be held at the sorbent surface allowing subsequent degradation leading to eventual mineralization [4,[6][7][8]. Research has produced a wide variety of schemes to immobilize TiO 2 or produce active particles of sizes allowing facile separation (approx.…”

β-FeSe nanorods composited g-C 3 N 4 with enhanced photocatalytic efficiency

“…The energy crisis and the increasingly serious environmental pollution problem are the severe challenges facing human survival and development [1][2][3][4]. Today, with the depletion of fossil energy, the use of clean solar energy has become an alternative solution.…”