Enhanced charge separation in TiO₂/nanocarbon hybrid photocatalysts through coupling with short carbon nanotubes

Abstract

The interfacial contact between TiO2 and graphitic carbon in a hybrid composite plays a critical role in electron transfer behavior, and in turn, its photocatalytic efficiency.

A Review on Nano Ti-Based Oxides for Dark and Photocatalysis: From Photoinduced Processes to Bioimplant Applications

“…The shorter SWCNT provides greater interfacial contact with each TiO 2 NP, more electron transport channels, and more efficient shuttling of electrons from TiO 2 NP to SWCNT, delaying charge recombination. Improved SWCNT debundling with the short ones also affords these advantages to a larger portion of the composite [ 166 ].…”

Revisiting the Role of Peroxymonosulfate in TiO2-Mediated Photocatalytic Oxidation: Dependence of Kinetic Enhancement on Target Substrate and Surface Platinization

“…The isomer distribution of the hydroxylated intermediates resulting from BA oxidation implied the capability of surface-loaded Pt NPs to kinetically assist the CB electron-mediated production of SO 4 •– from PMS, which was supported by LSV analysis on the RDE; the number of electrons involved in PMS activation over Pt-TiO 2 was close to 1.0. Noble metals (e.g., Au, Pt, and Pd) , and carbonaceous nanomaterials (e.g., carbon nanotubes and graphene oxide) , that serve as the electron sink to facilitate the separation of photogenerated charge carriers have been demonstrated to activate persulfate without radical production to initiate the selective organic oxidation. − Considering the contribution of nonphoton-driven PMS activation over Pt-TiO 2 , the extent of improvement in treatment performance via persulfate addition should be more pronounced when photocatalysts surface-modified with metal- and carbon-based cocatalysts are applied for the oxidative degradation of electron-rich organic contaminants. Accordingly, further studies are required to develop the TiO 2 modification strategies using an extended range of nanoscale noble metals and nanocarbons (presumed to serve as persulfate activators as well as CB electron sinks) to promote the overall treatment efficiency, avoid the competitive reactions between target contaminants and background organics for oxidants, and enable concerted catalysis and photocatalysis during light-dark cycles to reduce energy and persulfate consumption.…”

“…•− from PMS, which was supported by LSV analysis on the RDE; the number of electrons involved in PMS activation over Pt-TiO 2 was close to 1.0. Noble metals (e.g., Au, Pt, and Pd) 2,4 and carbonaceous nanomaterials (e.g., carbon nanotubes and graphene oxide) 49,50 that serve as the electron sink to facilitate the separation of photogenerated charge carriers have been demonstrated to activate persulfate without radical production to initiate the selective organic oxidation. 10−12 Considering the contribution of nonphoton-driven PMS activation over Pt-TiO 2 , the extent of improvement in treatment performance via persulfate addition should be more pronounced when photocatalysts surface-modified with metal-and carbon-based cocatalysts are applied for the oxidative degradation of electron-rich organic contaminants.…”

Functionalization of Pristine, Metallic, and Semiconducting-SWCNTs by ZnO for Efficient Charge Carrier Transfer: Analysis through Critical Coagulation Concentration

“…The noncovalent functionalization in composites shows complementing behavior due to the synergetic effect for both the building blocks, uplifting overall performance, e.g., functionalization of SWCNTs with metallic nanoparticles (Au/Ag) enhances the selective catalytic property and increase charge transfer . The most used catalytic nanoparticles include semiconductor oxides like ZnO, TiO 2 , CuO, SnO 2 , MoS 2 , etc., and SWCNTs–semiconductor oxide composites have become an attractive field of investigation for efficient charge transfer. − …”