Gas-Phase Fluorination of g-C3N4 for Enhanced Photocatalytic Hydrogen Evolution

Graphitic carbon nitride (g-C3N4) has attracted much attention because of its potential for application in solar energy conservation. However, the photocatalytic activity of g-C3N4 is limited by the rapidly photogenerated carrier recombination and insufficient solar adsorption. Herein, fluorinated g-C3N4 (F-g-CN) nanosheets are synthesized through the reaction with F2/N2 mixed gas directly. The structural characterizations and theoretical calculations reveal that fluorination introduces N vacancy defects, structural distortion and covalent C-F bonds in the interstitial space simultaneously, which lead to mesopore formation, vacancy generation and electronic structure modification. Therefore, the photocatalytic activity of F-g-CN for H2 evolution under visible irradiation is 11.6 times higher than that of pristine g-C3N4 because of the enlarged specific area, enhanced light harvesting and accelerated photogenerated charge separation after fluorination. These results show that direct treatment with F2 gas is a feasible and promising strategy for modulating the texture and configuration of g-C3N4-based semiconductors to drastically enhance the photocatalytic H2 evolution process.

Novel, Simple and Low-Cost Preparation of Ba-Modified TiO2 Nanotubes for Diclofenac Degradation under UV/Vis Radiation

A novel low-cost synthesis of barium-modified TiO2 nanotube (TNT) arrays was used to obtain an immobilized photocatalyst for degradation of diclofenac. TNT arrays were prepared by electrochemical anodization of titanium thin films deposited on fluorine-doped tin oxide (FTO) coated glass by magnetron sputtering, ensuring transparency and immobilization of the nanotubes. The Ba-modifications were obtained by annealing solutions of Ba(OH)2 spin coated on top of TNT. Three different concentrations of Ba(OH)2 were used (12.5 mM, 25 mM and 50 mM). The crystalline structure, morphology and presence of Ba were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. Ba-modified TiO2 nanotubes (BTNT) were tested for photocatalytic degradation of diclofenac under UV/Vis radiation and it was proven that all of the Ba-modified samples showed an increase in photocatalytic activity with respect to the unmodified TNTs. The most efficient photocatalyst was the sample prepared with 25 mM Ba(OH)2 which showed 90% diclofenac degradation after 60 min. This result was in agreement with cyclic voltammetry measurements that showed the largest increase in photo-oxidation current densities for the same sample due to the increased generation of •OH radicals obtained by a more efficient photogenerated charge separation.

The Cerium/Boron Insertion Impact in Anatase Nano-structures on the Photo-Electrochemical and Photocatalytic Response

Boron- and cerium-doped titania (Anatase) were prepared via sol-gel method. Phase composition and morphology were assessed by X-ray diffraction (XRD), scanning electronic microscopy (SEM), BET, diffuse reflectance spectra (DRS), and XPS. Photo-electrochemistry of these materials, deposited onto fluorine-doped SnO2 (FTO), was investigated in acid and acid-containing methanol. The boron-doped sample showed the best opto-electronic properties among the investigated samples. On the other hand, the cerium-doped titania samples annihilate to a certain extent the titania surface states, however, photogenerated charge separation was limited, and certainly associated to surface Ce3+/Ce4+ species. The substitutional effect of boron ions for O sites and interstitial sites was confirmed by XRD and XPS analyses.

CdSe Quantum Dots/White Graphene Hexagonal Porous Boron Nitride Sheet (h-PBNs) Heterostructure Photocatalyst for Solar Driven H2 Production

In the world of photocatalytic hydrogen (H2) evolution two-dimensional (2D) nanomaterials have attracted widespread attention owing to their high surface area, abundant active site, and excellent photogenerated charge separation properties....

Rutile TiO2 single crystals delivering enhanced photocatalytic oxygen evolution performance

Owing to their scientific and technological importance, the development of highly efficient photocatalytic water oxidation systems with rapid photogenerated charge separation and high surface catalytic activity has highly desirable for...

Visible-light-driven photocatalytic CO2 reduction over ketoenamine-based covalent organic frameworks: role of the host functional groups

Compared to the electron-withdrawing groups, the electron-donating groups in TpBD can accelerate the photogenerated charge separation and transfer, thereby improving the photocatalytic performance for photocatalytic CO2 reduction.

Enhancing the performance of photoelectrochemical glucose sensor via the electron cloud bridge of Au in SrTiO3/PDA electrodes

Developing photoelectrochemical biosensors via efficient photogenerated-charge separation remains a challenging task in biomolecule detection. In this work, a gold electron cloud bridge constructed at the interface is proposed to improve the efficiency of charge separation.

Boosting photocatalytic degradation of ethyl acetate by Z­scheme Au-TiO2@NH2-UiO-66 heterojunction with ultrafine Au as electron mediator

TiO2 based photocatalytic oxidation has been regarded as a promising technology for VOCs removal, while it remains challenging by the limited visible light response and low photogenerated charge separation efficiency....