Photocatalysis

About: Photocatalysis is a research topic. Over the lifetime, 67088 publications have been published within this topic receiving 2145233 citations. The topic is also known as: photocatalyst.

Degradation of Acid Blue 74 using Fe-ZSM5 zeolite as a heterogeneous photo-Fenton catalyst

Abstract: Decolourisation and mineralization of an indigoid dye, C.I. Acid Blue 74, was conducted using Fe-ZSM5 zeolite as a catalyst in the presence of UV-C light and H2O2. The effects of different parameters such as amounts of catalyst, initial concentration of the dye and H2O2 and initial pH of the dye solution on the degradation efficiency of the process were assessed. The results indicated that by using 21.4 mmol l−1 of H2O2 and 0.5 g l−1 of the catalyst at pH 5, about 57% total organic carbon of a solution containing 8.56 × 10−5 mol l−1 Acid Blue 74 could be removed after 120 min in a 2 l batch photo-reactor. Leaching tests indicated that the activity of the catalyst is not due to leached iron ions, although an amount of about 0.3 mg l−1 iron ions was found in the aqueous solution. Significantly lower concentration of Fe2+ and Fe3+ in the solution after the treatment could give a great advantage to UV/Fe-ZSM5/H2O2 system over the homogeneous Fenton-type system. It was found that by using this catalyst, it is possible to expand the range of pH values for which Fenton-type oxidation can occur and no iron hydroxide sludge is formed. It was also observed that catalytic behaviour could be reproduced in consecutive experiments without a considerable drop in the process efficiency.

Mediator-free direct Z-scheme photocatalytic system: BiVO4/g-C3N4 organic–inorganic hybrid photocatalyst with highly efficient visible-light-induced photocatalytic activity

Abstract: We disclose the fabrication of a mediator-free direct Z-scheme photocatalyst system BiVO4/g-C3N4 using a mixed-calcination method based on the more reliable interfacial interaction. The facet coupling occurred between the g-C3N4 (002) and BiVO4 (121), and it was revealed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The crystal structure and optical properties of the as-prepared samples have also been characterized by Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra (DRS) in details. The photocatalytic experiments indicated that the BiVO4/g-C3N4 composite photocatalysts display a significantly enhanced photocatalytic activity pertaining to RhB degradation and photocurrent generation (PC) compared to the pristine BiVO4 and g-C3N4. This remarkably improved photocatalytic performance should be attributed to the fabrication of a direct Z-scheme system of BiVO4/g-C3N4, which can result in a more efficient separation of photoinduced charge carriers than band–band transfer, thus endowing it with the much more powerful oxidation and reduction capability, as confirmed by the photoluminescence (PL) spectra and electrochemical impedance spectra (EIS). The Z-scheme mechanism of BiVO4/g-C3N4 heterostructure was verified by a series of combined techniques, including the active species trapping experiments, NBT transformation and terephthalic acid photoluminescence probing technique (TA-PL) over BiVO4/g-C3N4 composites and the pristine samples. The present work not only furthered the understanding of mediator-free Z-scheme photocatalysis, but also shed new light on the design of heterostructural photocatalysts with high-performance.

Enhancement of photocatalytic H2 evolution over nitrogen-deficient graphitic carbon nitride

Abstract: Nitrogen-deficient graphitic carbon nitride (g-C3N4−x) was synthesized by a hydrothermal treatment using ammonium thiosulfate as an oxidant. The as-prepared photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption–desorption, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis (EA), electron paramagnetic resonance (EPR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL) spectroscopy. The visible-light-driven photocurrent measurement was performed by several on–off cycles of intermittent irradiation. The photocatalytic activity of catalysts was evaluated by splitting water under visible-light irradiation (λ > 420 nm). Results demonstrated that the photoactivity of g-C3N4−x was enhanced greatly by the deficiency of the terminal amino species on the catalysts. The average H2 evolution rate on g-C3N4−x was 31.6 μmol h−1, which was ca. 3 times higher than that on pristine g-C3N4. It was revealed that the unique nitrogen-deficient structure of g-C3N4−x played an important role in broadened visible-light absorption and efficient electron–hole separation, mainly accounting for the improved photocatalytic activity.

Fabrication of NiS modified CdS nanorod p–n junction photocatalysts with enhanced visible-light photocatalytic H2-production activity

Abstract: Production of hydrogen from photocatalytic water splitting has become an attractive research area due to the possibility of converting solar energy into green chemical energy. In this study, novel NiS nanoparticle (NP) modified CdS nanorod (NR) p-n junction photocatalysts were prepared by a simple two-step hydrothermal method. Even without the Pt co-catalyst, the as-prepared NiS NP-CdS NR samples exhibited enhanced visible-light photocatalytic activity and good stability for H2-production. The optimal NiS loading content was determined to be 5 mol%, and the corresponding H2-production rate reached 1131 μmol h(-1) g(-1), which is even higher than that of the optimized Pt-CdS NRs. It is believed that the assembly of p-type NiS NPs on the surface of n-type CdS NRs could form a large number of p-n junctions, which could effectively reduce the recombination rates of electrons and holes, thus greatly enhancing the photocatalytic activity. This work not only shows a possibility for the utilization of low cost NiS nanoparticles as a substitute for noble metals (such as Pt) in the photocatalytic H2-production but also provides a new insight into the design and fabrication of other new p-n junction photocatalysts for enhancing H2-production activity.