Review of material design and reactor engineering on TiO2 photocatalysis for CO2 reduction

Synergistic effects of Zn and Pd species in TiO2 towards efficient photo-reduction of CO2 into CH4

TiO₂–PdX–ZnY exhibits significantly improved photo-reduction activity of CO₂ into CH₄.

Single step aerosol assisted chemical vapor deposition of p–n Sn(ii) oxide–Ti(iv) oxide nanocomposite thin film electrodes for investigation of photoelectrochemical properties

Novel p–n SnO–TiO₂ nanocomposite film electrodes were fabricated through a single step method and their photoelectrocatalytic properties were evaluated.

Ni-Nanocluster Modified Black TiO2 with Dual Active Sites for Selective Photocatalytic CO2 Reduction

One of the key challenges in artificial photosynthesis is to design a photocatalyst that can bind and activate the CO₂ molecule with the smallest possible activation energy and produce selective hydrocarbon products. In this contribution, a combined experimental and computational study on Ni-nanocluster loaded black TiO₂ (Ni/TiO_2[Vo] ) with built-in dual active sites for selective photocatalytic CO₂ conversion is reported. The findings reveal that the synergistic effects of deliberately induced Ni nanoclusters and oxygen vacancies provide (1) energetically stable CO₂ binding sites with the lowest activation energy (0.08 eV), (2) highly reactive sites, (3) a fast electron transfer pathway, and (4) enhanced light harvesting by lowering the bandgap. The Ni/TiO_2[Vo] photocatalyst has demonstrated highly selective and enhanced photocatalytic activity of more than 18 times higher solar fuel production than the commercial TiO₂ (P-25). An insight into the mechanisms of interfacial charge transfer and product formation is explored.

Metal-Organic Framework-Stabilized CO2/Water Interfacial Route for Photocatalytic CO2 Conversion

Here, we propose a CO₂/water interfacial route for photocatalytic CO₂ conversion by utilizing a metal-organic framework (MOF) as both an emulsifier and a catalyst. The CO₂ reduction occurring at the CO₂/water interface produces formate with remarkably enhanced efficiency as compared with that in conventional solvent. The route is efficient, facile, adjustable, and environmentally benign, which is applicable for the CO₂ transformation photocatalyzed by different kinds of MOFs.

Inorganic Nanoparticles/Metal Organic Framework Hybrid Membrane Reactors for Efficient Photocatalytic Conversion of CO2

Photocatalytic conversion of carbon dioxide (CO₂) to useful products has potential to address the adverse environmental impact of global warming. However, most photocatalysts used to date exhibit limited catalytic performance, due to poor CO₂ adsorption capacity, inability to efficiently generate photoexcited electrons, and/or poor transfer of the photogenerated electrons to CO₂ molecules adsorbed on the catalyst surface. The integration of inorganic semiconductor nanoparticles across metal organic framework (MOF) materials has potential to yield new hybrid materials, combining the high CO₂ adsorption capacity of MOF and the ability of the semiconductor nanoparticles to generate photoexcited electrons. Herein, controlled encapsulation of TiO₂ and Cu-TiO₂ nanoparticles within zeolitic imidazolate framework (ZIF-8) membranes was successfully accomplished, using rapid thermal deposition (RTD), and their photocatalytic efficiency toward CO₂ conversion was investigated under UV irradiation. Methanol and carbon monoxide (CO) were found to be the only products of the CO₂ reduction, with yields strongly dependent upon the content and composition of the dopant semiconductor particles. CuTiO₂ nanoparticle doped membranes exhibited the best photocatalytic performance, with 7 μg of the semiconductor nanoparticle enhancing CO yield of the pristine ZIF-8 membrane by 233%, and methanol yield by 70%. This work opens new routes for the fabrication of hybrid membranes containing inorganic nanoparticles and MOFs, with potential application not only in catalysis but also in electrochemical, separation, and sensing applications.

Photocatalytic performance of Cu2O-loaded TiO2/rGO nanoheterojunctions obtained by UV reduction

A novel dot-like Cu₂O-loaded TiO₂/reduced graphene oxide (rGO) nanoheterojunction was synthesized via UV light reduction for the first time. Cu₂O with size of ca. 5 nm was deposited on rGO sheet and TiO₂ nanosheets. The products were characterized by infrared spectroscopy, Raman spectrum, UV-Vis diffuse reflectance spectra, XPS techniques, photoluminescence spectra. The results demonstrated that Cu₂O and rGO enhanced the absorption for solar light, separation efficiency of electron-hole pairs, charge shuttle and transfer, and eventually improved photoelectrochemical and photocatalytic performance for contaminants degradation. The reaction time and anion precursor could affect the final copper-containing phase. As extending UV irradiation time, Cu²⁺ was be first reduced to Cu₂O and then transformed to metal Cu. In comparison with CH₃COO^- (copper acetate), NO₃^- (copper nitrate) and Cl^- (copper chloride), SO₄^2- (copper sulfate) was the optimum for synthesizing pure Cu₂O phase.

Synergistically enhanced photocatalytic reduction of CO2 on N–Fe codoped BiVO4 under visible light irradiation

Synergistically enhanced visible-light-driven catalytic reduction of CO₂ with H₂O to CH₃OH over N–Fe codoped BiVO₄.

Improving the visible light photoelectrochemical activity of synthesized TiO2nanotube arrays in an organic electrolyte containing sodium carbonate with doping by copper via single-step anodization

The main aim of this research is to improve the photocatalytic activity of TiO₂nanotubes by co-doping with copper and sodium for application in the water splitting process as a photoanode.

TiO2–Pd/C composited photocatalyst with improved photocatalytic activity for photoreduction of CO2 into CH4

O–Pd–O surface species and carbon enhance the visible response and separate photogenerated charge carriers effectively.

Influence of Cu doping on the visible-light-induced photocatalytic activity of InVO4

The photocatalytic degradation of methylene blue (MB) in the presence of pure InVO₄ and 0.5–5.0 mol% Cu-doped InVO₄ samples under visible light irradiation (λ ≥ 400 nm) was studied in this research.

Facile synthesis of g-C3N4 nanosheets loaded with WO3 nanoparticles with enhanced photocatalytic performance under visible light irradiation

Possible synthesis and degradation mechanism for photocatalysts under visible light irradiation.

La2Sn2O7 enhanced photocatalytic CO2 reduction with H2O by deposition of Au co-catalyst

La₂Sn₂O₇ (LSO) micro/nanospheres, synthesized by a hydrothermal method, exhibited photocatalytic performance for CO₂ reduction.

Mutual-stabilization in chemically bonded graphene oxide–TiO2 heterostructures synthesized by a sol–gel approach

The Ti–O–C interactions between GO and TiO₂ are strong enough to induce mutual shaping during synthesis and thermal treatment.

Preparation of TiO₂-Decorated Boron Particles by Wet Ball Milling and their Photoelectrochemical Hydrogen and Oxygen Evolution Reactions

TiO₂-coated boron particles were prepared by a wet ball milling method, with the particle size distribution and average particle size being easily controlled by varying the milling operation time. Based on the results from X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy, it was confirmed that the initial oxide layer on the boron particles surface was removed by the wet milling process, and that a new B-O-Ti bond was formed on the boron surface. The uniform TiO₂ layer on the 150 nm boron particles was estimated to be 10 nm thick. Based on linear sweep voltammetry, cyclic voltammetry, current-time amperometry, and electrochemical impedance analyses, the potential for the application of TiO₂-coated boron particles as a photoelectrochemical catalyst was demonstrated. A current of 250 μA was obtained at a potential of 0.5 V for hydrogen evolution, with an onset potential near to 0.0 V. Finally, a current of 220 μA was obtained at a potential of 1.0 V for oxygen evolution.

TiO2 Nanotubes Arrays Loaded with Ligand-Free Au Nanoparticles: Enhancement in Photocatalytic Activity

A new protocol to synthesize size-controlled Au nanoparticles (NPs) loaded onto vertically aligned anatase TiO₂ nanotubes arrays (TNTAs) prepared by electrochemical anodization is reported. Ligand-free Au NPs (<10 nm) were deposited onto anatase TNTAs supports, finely tuning the Au loading by controlling the immersion time of the support into metal vapor synthesis (MVS)-derived Au-acetone solutions. The Au/TNTAs composites were characterized by electron microscopies (SEM, (S)TEM), X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis spectroscopy. Their photocatalytic efficiency was evaluated in toluene degradation in air under ambient conditions without thermal or chemical postsynthetic treatments. The role of Au loadings was pointed out, obtaining a three times enhancement of the pristine anatase TNTAs activity with the best sample containing 3.3 μg Au cm^-2.

Novel g-C3N4/Ag2SO4 nanocomposites: Fast microwave-assisted preparation and enhanced photocatalytic performance towards degradation of organic pollutants under visible light

Graphite carbon nitride (g-C3N4)/Ag2SO4 nanocomposites, as highly enhanced visible-light-driven photocatalysts, were prepared by a fast microwave-assisted method. The resulting g-C3N4/Ag2SO4 nanocomposites were characterized by X-ray diffraction, energy dispersive analysis of X-rays, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, Fourier transform-infrared spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy techniques. Moreover, charge separation efficiency was studied by photoluminescence measurements. Photocatalytic activity of the g-C3N4/Ag2SO4 (40%) nanocomposite in degradation of rhodamine B, methylene blue, and fuchsine is about 6, 3.8, and 3.3-folds greater than that of the g-C3N4 under visible-light illumination. Effect of microwave irradiation time, calcination temperature, and scavengers of the reactive species on the degradation reaction was also evaluated. The enhanced photocatalytic activity was mainly ascribed to the matching band energies of g-C3N4 and Ag2SO4 which leads to an improved separation of photogenerated electron-hole pairs. Finally, the optimized nanocomposite was recycled for five times without remarkable decrease of the photocatalytic activity.