Origin Of Photocatalytic Activity Research Articles

Enhancement of photocatalytic NOx abatement on titania via additional metal oxide NOx-storage domains: Interplay between surface acidity, specific surface area, and humidity

In this work, we propose a simple and effective preparation procedure to obtain ternary mixed oxides composed of titania (TiO2, P25), alumina (γ-Al2O3) and calcium oxide (CaO) functioning as efficient photocatalytic NOx oxidation and storage (PHONOS) catalysts that are capable of facile NOx abatement under ambient conditions in the absence of elevated temperatures and pressures with UVA irradiation. In this architecture, titania was the photocatalytic active component and CaO and/or γ-Al2O3 provided NOx storage domains revealing dissimilar specific surface areas (SSA) and surface acidities. We show that photocatalyst formulation can be readily fine-tuned to achieve superior photocatalytic performance surpassing conventional P25 benchmark in short (1 h) and long term (12 h), as well as humidity-dependent photocatalytic tests. We demonstrate the delicate interplay between the surface acidity, SSA and humidity and provide detailed mechanistic insights regarding the origin of photocatalytic activity, selectivity and deactivation pathways.

Cover Feature: The Hazardous Origin of Photocatalytic Activity of ZnCr2O4 (Z. Anorg. Allg. Chem. 12‐13/2018)

Cover Feature: The Hazardous Origin of Photocatalytic Activity of ZnCr₂O₄ (Z. Anorg. Allg. Chem. 12‐13/2018)

The enrichment of photo-catalysis via self-assembly perylenetetracarboxylic acid diimide polymer nanostructures incorporating TiO2 nano-particles

This paper reports that hybrid titanium dioxide (TiO2) packaged self-assembly perylenetetracarboxylic acid diimide (PTCDI) by self-assembly. These were synthesized through simple mechanical milling that has great photocatalytic performance under visible light. The PTCDI@TiO2 composite had high activity for the degradation of phenol and 2,4-dichlorophenol, which were 2.3 and 3.2 times of the monomer PTCDI, respectively. After three cycles, the activity of the composite catalyst remained at 70%. Further analysis showed that the photocatalytic activity and stability are mainly due to the enhancement of the charge mobility by the π-π conjugated structure in PTCDI. Moreover, the good energy level matching between PTCDI and TiO2 helps to separate the electron-hole, thus improving the photocatalytic performance of the composite. The origin of photocatalytic activity was greatly improved due to holes and O2−, which was mainly attributed to the strong interaction between PTCDI and TiO2.

Insight Into the Origin of Photocatalytic Activity of Ag3VO4 and Improved Approaches for Its Photoactivity Based on First-Principles

Insight Into the Origin of Photocatalytic Activity of Ag₃VO₄ and Improved Approaches for Its Photoactivity Based on First-Principles

Template-free synthesis of MgO nanoparticles for effective photocatalytic applications

MgO nanoparticles were synthesized by template-free reflux condensation approach. XRD and FTIR confirmed the formation of single phase MgO exhibiting cubic crystal structure. SEM and TEM analysis revealed the formation of MgO nanoflakes. The optical band gap of MgO nanoparticles estimated from UV DRS was in the range 5.40–5.45eV. PL spectra of MgO nanoparticles showed visible emissions due to the formation of defects in the band gap region of MgO. Synthesized MgO nanoparticles exhibited appreciable photocatalytic activity for the degradation of methyl orange and methylene blue dyes under UV light irradiation. Results demonstrated that the origin of photocatalytic activity in MgO arises due to the existence of high concentration of native defects on the surface of MgO.

Origin of Photocatalytic Activity in Continuous Gas Phase CO2 Reduction over Pt/TiO2

The dynamic nature of continuous photocatalytic reduction of gaseous CO2 in the presence of water vapor was studied by using Pt/TiO2 as catalyst under UV irradiation at 353 and 423 K in the absence of sacrificial electron donors. The reaction was studied with a good time resolution (order of seconds), to monitor product concentrations by means of mass spectrometry. Two distinct photocatalytic activities, namely steady-state and transient, were identified. The former is active at the lower temperature and only for H2 production, whereas the latter dominates for CH4 production. The transient activity was recovered during dark time (i.e., the light is off) in the reaction mixture, with the magnitude of recovery proportionally increasing with the duration of the dark time. Higher temperature was found to be more effective for the recovery. Furthermore, insights into deactivation and reactivation mechanisms are explained by in situ diffuse reflectance infrared Fourier transform spectroscopy study.

Effect of doping by boron, carbon, and nitrogen atoms on the magnetic and photocatalytic properties of anatase

The effect of doping of titanium dioxide with the anatase structure by boron, carbon, and nitrogen atoms on the magnetic and optical properties and the electronic spectrum of this compound has been investigated using the ab initio tight-binding linear muffin-tin orbital (TB-LMTO) band-structure method in the local spin density approximation explicitly including Coulomb correlations (LSDA + U) in combination with the semiempirical extended Huckel theory (EHT) method. The LSDA + U calculations of the electronic structure, the imaginary part of the dielectric function, the total magnetic moments, and the magnetic moments at the impurity atoms have been carried out. The diagrams of the molecular orbitals of the clusters Ti3 X (X = B, C, N) have been calculated and the pseudo-space images of the molecular orbitals of the clusters have been constructed. The effect of doping on the nature and origin of photocatalytic activity in the visible spectral range and the specific features of the generation of ferromagnetic interactions in doped anatase have been discussed based on the analysis of the obtained data. It has been shown that, in the sequence TiO2 − y N y → TiO2 − y C y → TiO2 − y B y (y = 1/16), the photocatalytic activity can increase with the generation of electronic excitations with the participation of impurity bands. The calculated magnetic moments for boron and nitrogen atoms are equal to 1 μB, whereas the impurity carbon atoms are nonmagnetic.