Biomineralized N-Doped CNT/TiO₂ Core/Shell Nanowires for Visible Light Photocatalysis

Abstract

We report an efficient and environmentally benign biomimetic mineralization of TiO(2) at the graphitic carbon surface, which successfully created an ideal TiO(2)/carbon hybrid structure without any harsh surface treatment or interfacial adhesive layer. The N-doped sites at carbon nanotubes (CNTs) successfully nucleated the high-yield biomimetic deposition of a uniformly thick TiO(2) nanoshell in neutral pH aqueous media at ambient pressure and temperature and generated N-doped CNT (NCNT)/TiO(2) core/shell nanowires. Unlike previously known organic biomineralization templates, such as proteins or peptides, the electroconductive and high-temperature-stable NCNT backbone enabled high-temperature thermal treatment and corresponding crystal structure transformation of TiO(2) nanoshells into the anatase or rutile phase for optimized material properties. The direct contact of the NCNT surface and TiO(2) nanoshell without any adhesive interlayer introduced a new carbon energy level in the TiO(2) band gap and thereby effectively lowered the band gap energy. Consequently, the created core/shell nanowires showed a greatly enhanced visible light photocatalysis. Other interesting synergistic properties such as stimuli-responsive wettabilites were also demonstrated.

Lanthanum‐Doped TiO2 Nanosheet Film with Highly Reactive {001} Facets and Its Enhanced Photocatalytic Activity

“…O 2 -+ dye (MO or MB) → degraded products (8) · OH + dyes (MO or MB) → degraded products (9) Full Paper…”

“…[4][5][6] To solve these problems, many recent studies have investigated the immobilization of TiO 2 nanoparticles on a solid carrier and the variation of their electronic structure through doping with metallic and nonmetallic elements. [4,[7][8][9] Recently, La doping has become highly promising because [10][11][12][13] it can (1) reduce electron-hole pair recombination owing to the 4f electron configuration of La and (2) promote the chemical adsorption of organic substrates on the TiO 2 crystal surfaces.…”

A critical review of nanohybrids: synthesis, applications and environmental implications

“…For example, the photoactivity of TiO 2 (under visible light) has been shown to enhance upon conjugation with CNTs or graphene, because of lowering of the bandgap energy. [73,170] Such enhancement is attributed to the synergy in electronic properties between titania and carbon nanostructures; e.g. small-sized TiO 2 particles on CNT surfaces reduce the electron-hole pair recombination rate and thus enhance the photoactivity.…”

Significant Enhancement of the Photoelectrochemical Activity of Nanoporous TiO 2 for Environmental Applications

“…However, due to its large band gap ($3.0 eV for rutile and $3.2 eV for anatase) [23][24][25][26], TiO 2 remains an inefficient candidate for utilization of solar energy. Therefore, it is desirable to perform band gap engineering to potentially enable this material for practical use.…”