Efficient Photocatalytic Bilirubin Removal over the Biocompatible Core/Shell P25/g-C3N4 Heterojunctions with Metal-free Exposed Surfaces under Moderate Green Light Irradiation

Actinyl-Modified g-C3N4 as CO2 Activation Materials for Chemical Conversion and Environmental Remedy via an Artificial Photosynthetic Route

With the reported CO₂ activation for the oxidation of benzene to phenol (-ENE → -OL) by the graphitic carbon nitride g-C₃N₄ (CN) via an artificial photosynthetic route as inspiration, high-valent actinyls (An^mO₂)ⁿ⁺ (An = U, Np, Pu; m = VI, V; n = 2, 1) have been introduced for its further modification. Our calculations indicate thermodynamic spontaneity in the feasibility of g-C₃N₄-(An^mO₂)ⁿ⁺ (CN-An^m) formation. The magnificent structural and electronic properties of CN-An^m are utilized for CO₂ activation in terms of the rarely studied -ENE → -OL conversion. The calculated free energies show that most steps of the catalytic cycle are favored by CN-An^m complexes. The first step (carbamate formation) is slightly endothermic in all cases, where CN-U is 0.51 eV higher than CN and CN-Pu is -0.01 eV lower. All benzene addition reactions release energy, with that for CN-U being the lowest. The phenolate formation is favored by some actinyl complexes over CN, and CN-U is only 0.23 eV higher. The phenol release (resulting in formamide complexes) and CO desorption are exothermic for all CN-An^m. The overall process suggests the improved catalytic performance of actinyl-modified CN materials, and the slightly depleted uranyl-carbon nitride could be one of the promising catalysts.

Cellulose-Derived Hierarchical g-C3N4/TiO2-Nanotube Heterostructured Composites with Enhanced Visible-Light Photocatalytic Performance

A novel cellulose-derived hierarchical g-C₃N₄/TiO₂-nanotube heterostructured nanocomposite was fabricated by in situ coating thin g-C₃N₄ layers onto the surfaces of the TiO₂ nanotubes, which were synthesized by utilizing the natural cellulose substance (e.g., commercial ordinary filter paper) as the structural template. These g-C₃N₄/TiO₂-nanotube composites with varied thicknesses (ca. 3-30 nm) of the outer g-C₃N₄ layers displayed improved visible-light (λ > 420 nm)-driven photocatalytic degradation performances toward methylene blue. The optimal nanocomposite with an outer g-C₃N₄ layer of ca. 7.5 nm composed of 46 wt % g-C₃N₄ displayed an apparent rate constant of 0.0035 min^-1, which was 8.5- and 4-fold larger than those of the referential TiO₂-nanotube and g-C₃N₄ powder. The excellent and durable photocatalytic activities of these cellulose-derived g-C₃N₄/TiO₂-nanotube composites were ascribed to their hierarchically network porous structures replicated from the cellulose template, as well as the formation of close heterojunctions in-between the g-C₃N₄ and TiO₂ phases. Moreover, it was demonstrated that the photocatalytic mechanism matched with the type-II heterostructured model, while the main effective species during the photocatalytic processes of the nanocomposite were proved to be superoxide radicals.

Au Nanoclusters Sensitized Black TiO2-x Nanotubes for Enhanced Photodynamic Therapy Driven by Near-Infrared Light

The low reactive oxygen species production capability and the shallow tissue penetration of excited light (UV) are still two barriers in photodynamic therapy (PDT). Here, Au cluster anchored black anatase TiO_2-x nanotubes (abbreviated as Au₂₅ /B-TiO_2-x NTs) are synthesized by gaseous reduction of anatase TiO₂ NTs and subsequent deposition of noble metal. The Au₂₅ /B-TiO_2-x NTs with thickness of about 2 nm exhibit excellent PDT performance. The reduction process increased the density of Ti³⁺ on the surface of TiO₂ , which effectively depresses the recombination of electron and hole. Furthermore, after modification of Au₂₅ nanoclusters, the PDT efficiency is further enhanced owing to the changed electrical distribution in the composite, which forms a shallow potential well on the metal-TiO₂ interface to further hamper the recombination of electron and hole. Especially, the reduction of anatase TiO₂ can expend the light response range (UV) of TiO₂ to the visible and even near infrared (NIR) light region with high tissue penetration depth. When excited by NIR light, the nanoplatform shows markedly improved therapeutic efficacy attributed to the photocatalytic synergistic effect, and promotes separation or restrained recombination of electron and hole, which is verified by experimental results in vitro and in vivo.