Synthesis of magnetic graphene-like carbon nitride-cobalt ferrite (g-C3N4/CoFe2O4) nanocomposite for sonocatalytic remediation of toxic organic dyes

A novel magnetic g-C₃N₄/CoFe₂O₄ nanocomposite was successfully synthesized by a simple hydrothermal method and applied as a new graphene-like carbon nitride-based sonocatalyst for sonodegradation of pollutant dyes. The as-prepared samples were characterized by using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS), BET surface area measurements and photoluminescence (PL) spectroscopy. The results indicate that the nanocomposite sample is composed of spherical CoFe₂O₄ nanoparticles adhered to g-C₃N₄ naosheets. The g-C₃N₄/CoFe₂O₄ nanocomposites were used as a new magnetically separable sonocatalyst in H₂O₂-assisted sonodegradation of methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes in aqueous media. The results showed complete degradation (ca. 100%) of dyes within short times (30-35 min). The sonocatalytic activity of graphitic carbon nitride (g-C₃N₄) was greatly enhanced with CoFe₂O₄ modification. Trapping experiments indicated that the g-C₃N₄/CoFe₂O₄ nanocomposites serves as a generator of hydroxyl radical (˙OH) via activation of H₂O₂ for degradation of dyes under ultrasound irradiation. Furthermore, the magnetic sonocatalyst can be separated from solution by an external magnet and reused several times without observable loss of activity. The possible mechanism of sonocatalytic activity was also proposed according to experimental results.

Photocatalysis and perovskite oxide-based materials: a remedy for a clean and sustainable future

The massive use of non-renewable energy resources by humankind to fulfill their energy demands is causing severe environmental issues. Photocatalysis is considered one of the potential solutions for a clean and sustainable future because of its cleanliness, inexhaustibility, efficiency, and cost-effectiveness. Significant efforts have been made to design highly proficient photocatalyst materials for various applications such as water pollutant degradation, water splitting, CO2 reduction, and nitrogen fixation. Perovskite photocatalyst materials are gained special attention due to their exceptional properties because of their flexibility in chemical composition, structure, bandgap, oxidation states, and valence states. The current review is focused on perovskite materials and their applications in photocatalysis. Special attention has been given to the structural, stoichiometric, and compositional flexibility of perovskite photocatalyst materials. The photocatalytic activity of perovskite materials in different photocatalysis applications is also discussed. Various mechanisms involved in photocatalysis application from wastewater treatment to hydrogen production are also provided. The key objective of this review is to encapsulate the role of perovskite materials in photocatalysis along with their fundamental properties to provide valuable insight for addressing future environmental challenges.

Effects of RhCrOx Cocatalyst Loaded on Different Metal Doped LaFeO3 Perovskites with Photocatalytic Hydrogen Performance under Visible Light Irradiation

Photocatalytic hydrogen (H2) production by water splitting provides an alternative to fossil fuels using clean and renewable energy, which gives important requirements about the efficiency of photocatalysts, co-catalysts, and sacrificial agents. To achieve higher H2 production efficiencies from water splitting, the study uses different metals such as yttrium (Y), praseodymium (Pr), magnesium (Mg), Indium (In), calcium (Ca), europium (Eu), and terbium (Tb) doped lanthanum iron oxide (LaFeO3) perovskites. They were synthesized using a co-precipitate method in a citric acid solution, which was loaded with the rhodium chromium oxide (RhCrOx) cocatalysts by an impregnation method along with a detailed investigation of photocatalytic hydrogen evolution performance. Photoluminescence (PL) and UV–Vis diffuse reflectance spectra (DRS) measured the rate of electron–hole recombination for RhCrOx/Pr-LaFeO3 photocatalysts, and X-ray powder diffraction (XRD), scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), and X-ray photoelectron spectra (XPS) analyzed their characteristics. The experimental results obtained show that the samples with 0.5 wt.% RhCrOx loading and 0.1 M Pr-doped LaFeO3 calcined at a temperature of 700 °C (0.1Pr-LaFeO3-700) exhibited the highest photocatalytic H2 evolution rate of 127 µmol h−1 g−1, which is 34% higher photocatalytic H2 evolution performance than undoped LaFeO3 photocatalysts (94.8 μmol h−1 g−1). A measure of 20% of triethanolamine (TEOA) enabled a high hole capture capability and promoted 0.1-Pr-LaFeO3-700 to get the highest H2 evolution rate.

High potential and robust ternary LaFeO3/CdS/carbon quantum dots nanocomposite for photocatalytic H2 evolution under sunlight illumination

Exploitation of the novel, robust, and advanced photocatalytic systems with high efficiency is the present demand for clean, green, and sustainable energy production. Carbon quantum dots (CQDs) have attracted tremendous interest in efficient H₂ evolution from photocatalysis due to its remarkable visible-light harvesting and electron transport properties. Here, for the first time, a smart ternary nanocomposite comprises encapsulated CQDs with LaFeO₃ spherical nanoparticles and CdS nanorods is synthesized by a simple hydrothermal procedure for the efficient photocatalytic H₂ evolution under sunlight illumination. PXRD, FT-IR, FE-SEM, TEM, and XPS studies are performed to ensure the successful fabrication of ternary LaFeO₃/CdS/CQD nanocomposite. The efficient H₂ evolution rate (HER) of 25,302 μmol h^-1 g_cat^-1 is achieved for LaFeO₃/CdS/CQD nanocomposite, which is 602.4, 2.6, 29.8, 2.0 and 1.1 times higher than that of pristine LaFeO₃, pristine CdS, and composites such as LaFeO₃/CdS, LaFeO₃/CQD, and CdS/CQD. Photocurrent and lifetime PL studies reveal, encapsulation of CQDs with the LaFeO₃/CdS heterojunction can facilitate easy and efficient separation of photo-generated excitons. Altogether the fabrication of CQDs provides an ideal avenue for the development of high potential advanced photocatalytic systems for sustainable H₂ production with remarkable efficiencies.

A novel n-type CdS nanorods/p-type LaFeO3 heterojunction nanocomposite with enhanced visible-light photocatalytic performance

In this work, a novel n-type CdS nanorods/p-type LaFeO3 (CdS NRs/LFO) nanocomposite was prepared, for the first time, via a facile solvothermal method. The as-prepared n-CdS NRs/p-LFO nanocomposite was characterized by using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), UV-visible diffuse reflection spectroscopy (DRS), vibrating sample magnetometry (VSM), photoluminescence (PL) spectroscopy, and Brunauer-Emmett-Teller (BET) surface area analysis. All data revealed the attachment of the LFO nanoparticle on the surface of CdS NRs. This novel nanocomposite was applied as a novel visible light photocatalyst for the degradation of methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes under visible-light irradiation. Under optimized conditions, the degradation efficiency was 97.5% for MB, 80% for RhB and 85% for MO in the presence of H2O2 and over CdS NRs/LFO nanocomposite. The photocatalytic activity of CdS NRs/LFO was almost 16 and 8 times as high as those of the pristine CdS NRs and pure LFO, respectively. The photocatalytic activity was enhanced mainly due to the high efficiency in separation of electron-hole pairs induced by the remarkable synergistic effects of CdS and LFO semiconductors. After the photocatalytic reaction, the nanocomposite can be easily separated from the reaction solution and reused several times without loss of its photocatalytic activity. Trapping experiments indicated that ·OH radicals were the main reactive species for dye degradation in the present photocatalytic system. On the basis of the experimental results and estimated energy band positions, the mechanism for the enhanced photocatalytic activity was proposed.

Electrodeposition of carbon nitride nanosheets on the graphenized pencil lead as an effective sorbent

This study introduces a green, cheap, easy to prepare and powerful solid phase microextraction (SPME) sorbent for analytical monitoring applications.

Enhanced photocatalytic performance and stability of visible-light-driven Z-scheme CdS/Ag/g-C3N4 nanosheets photocatalyst

A novel Z-scheme CdS/Ag/g-C₃N₄ nanosheets photocatalyst was synthesized by combining the hydrothermal and photo-deposition techniques, where Ag nanoparticles as carrier transport channels significantly improve the separation efficiency of electron–hole pairs.