A facile approach to fabricating carbonaceous material/g-C3N4 composites with superior photocatalytic activity

Design and Fabrication of Biomass Derived Black Carbon Modified g-C3N4/FeIn2S4 Heterojunction as Highly Efficient Photocatalyst for Wastewater Treatment

The environmental deterioration caused by dye wastewater discharge has received considerable attention in recent decades. One of the most promising approaches to addressing the aforementioned environmental issue is the development of photocatalysts with high solar energy consumption efficiency for the treatment of dye-contaminated water. In this study, a novel low-cost π-π biomass-derived black carbon modified g-C3N4 coupled FeIn2S4 composite (i.e., FeInS/BC-CN) photocatalyst is successfully designed and fabricated that reveals significantly improved photocatalytic performance for the degradation of Eosin Yellow (EY) dye in aqueous solution. Under dark and subsequent visible light irradiation, the amount optimized composite reveals 99% removal performance for EY dye, almost three-fold compared to that of the pristine FeInS and BC-CN counterparts. Further, it is confirmed by means of the electron spin resonance spectrometry, quenching experiments, and density functional theory (DFT) calculations, that the hydroxyl radicals (•OH) and superoxide radicals (•O2 -) are the dominant oxidation species involved in the degradation process of EY dye. In addition, a systematic photocatalytic degradation route is proposed based on the resultant degradation intermediates detectedduring liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. This work provides an innovative idea for the development of advanced photocatalysts to mitigate water pollution.

Solvent Etching Process for Graphitic Carbon Nitride Photocatalysts Containing Platinum Cocatalyst: Effects of Water Hydrolysis on Photocatalytic Properties and Hydrogen Evolution Behaviors

In this study, we synthesized Pt/g-C₃N₄ photocatalysts modified by a solvent etching process where ethanol (Pt/CN0), water (Pt/CN100), and a 50:50 mixture (Pt/CN50) were used as a solvent, and investigated the optimal properties of g-C₃N₄ to prepare the best Pt/g-C₃N₄ for photocatalytic hydrogen evolution. From diverse characterizations, water was proven to be a stronger solvent agent, resulting in not only the introduction of more O-functional groups onto the g-C₃N₄ surface, but also the degradation of a regular array of tri-s-triazine units in the g-C₃N₄ structure. While the addition of O-functional groups positively influenced the oxidation state of the Pt cocatalyst and the hydrogen production rate, the changes to g-C₃N₄ structure retarded charge transfer on its surface, inducing negative effects such as fast recombination and less oxidized Pt species. Pt/CN50 that was synthesized with the 50:50 solvent mixture exhibited the highest hydrogen production rate of 590.9 µmol g⁻¹h⁻¹, while the hydrogen production rates of Pt/CN0 (with pure ethanol solvent) and Pt/CN100 (with pure water solvent) were 462.7, and 367.3 µmol g⁻¹h⁻¹, respectively.

Nanocellulose-derived carbon/g-C3N4 heterojunction with a hybrid electron transfer pathway for highly photocatalytic hydrogen peroxide production

Using oxygen reduction for the photocatalytic production of hydrogen peroxide (H₂O₂) has been considered a green and sustainable route. In the present study, to achieve high efficiency, graphitic carbon nitride (g-C₃N₄) was obtained using thermal polymerization from a bi-component precursor and was then assembled with cellulose nanofibers. It was found that a small quantity of cellulose nanofibers that generates carbon fibers upon pyrolysis greatly improves the photocatalytic activity compared with that of g-C₃N₄ alone. The well-defined carbon/g-C₃N₄ heterojunction-type material exhibits as high as 1.10 mmol L^-1h^-1 of photo-production of H₂O₂ under visible light, which is 4.2 times higher than that yielded by pristine g-C₃N₄ from a single precursor. A comprehensive characterization of the photocatalyst enables us to delineate the effect of the carbon nanofiber with respect to porosity, electron-hole separation, band gap regulation, and especially the electron transfer pathway. Our results demonstrate that nanocellulose-derived carbon, when precisely assembled with other functional material such as a photocatalyst, is a promising promoter of their activity.

Mechanistic insight into photocatalytic CO2 reduction by a Z-scheme g-C3N4/TiO2 heterostructure

The Z-scheme g-C₃N₄/TiO₂ heterostructure has remarkable catalytic activity for reducing CO₂ to CH₄ and CH₃OH.

Graphitic carbon nitride-doped sewage sludge as a novel material for photodegradation of Eriochrome Black T

The bio-resource utilization of sewage sludge is presented by preparation of novel waste sludge-doped graphite carbon nitride (g-C₃N₄) photocatalyst. The sludge flocs which constitute bacteria and organic substances served as a pore-forming framework in the catalyst, while the inorganic fractions including those transition metals and crustal metals can function as dopants for sludge-based g-C₃N₄ composite. The physicochemical properties of as-prepared catalyst were well analyzed by multiple characterizations. The composite catalyst showed higher surface area (50 m²/g) and more mesoporous structures (8.9 × 10^-2 cm³/g) as compared with pristine g-C₃N₄ (8.4 m²/g and 6.6 × 10^-2 cm³/g, respectively). The photoelectrochemical results showed that introduced sewage sludge impurities lowered down the photocarriers recombination efficiency and enhanced more efficient electron-hole separation by about 100 times. The photocatalytic activity was tested by degradation of typical dye Eriochrome Black T (EBT). The optimal sample improved removal of EBT by 56% in 90 min under ultraviolet irradiation (λ = 254 nm). According to the results of main metal ion leaching concentration and reuse tests, the composite catalyst exhibited excellent stability and repeatability.

Non-precious molybdenum nanospheres as a novel cocatalyst for full-spectrum-driven photocatalytic CO2 reforming to CH4

Photocatalytic CO₂ reforming is considered to be an effective method for clean, low-cost, and environmentally friendly reduction and conversion of CO₂ into hydrocarbon fuels by utilizing solar energy. However, the low separation efficiency of charge carriers and deficient reactive sites have severely hampered the efficiency of the photocatalytic CO₂ reforming process. Therefore, cocatalysts are usually loaded onto the surface of semiconductor photocatalysts to reduce the recombination of charge carriers and accelerate the rates of surface reactions. Herein, molybdenum (Mo) nanospheres are proposed as a novel non-precious cocatalyst to enhance the photocatalytic CO₂ reforming of g-C₃N₄ significantly. The Mo nanospheres boost the adsorption of CO₂ and activate the surface CO₂via a photothermal effect. The time-resolved fluorescence decay spectra reveals that the lifetime of photo-induced charge carriers is prolonged by the Mo nanospheres, which guarantees the migration of charge carriers from g-C₃N₄ to Mo nanospheres. Unexpectedly, Mo loaded g-C₃N₄ can effectively utilize a wide spectral range from UV to near-infrared region (NIR, up to 800 nm). These findings highlight the potential of Mo nanospheres as a novel cocatalyst for photocatalytic CO₂ reforming to CH₄.

Ce-Doped Graphitic Carbon Nitride Derived from Metal Organic Frameworks as a Visible Light-Responsive Photocatalyst for H2 Production

Novel fibrous graphitic carbon nitride (g-C₃N₄) derivatives prepared from metal organic frameworks (MOFs) were doped with Ce³⁺ (Ce-C₃N₄) as photocatalytic materials. Ce-C₃N₄ was characterized using various techniques, revealing its high specific surface area, excellent photocatalytic activity, and stability for H₂ evolution under visible light irradiation. The fluorine modified samples show superior photocatalytic activity under visible light irradiation, which is due to the presence of more active sites and enhanced absorption of solar energy. This work provides a new synthetic route for MOF-derived g-C₃N₄ that can be doped with different metal ions. The fluorine modified Ce-C₃N₄ is an efficient photocatalyst with potential for many applications related to energy and the environment.