Novel High Efficiency Layered Oxide Photocatalyst Li2SnO3 for Rhodamine B and Tetracycline Degradation

Mechanism of p-Type Heteroatom Doping of Lithium Stannate for the Photodegradation of 2,4-Dichlorophenol: Enhanced Hole Oxidative Capability and Concentrations

A systematic evaluation of enhancing photocatalysis via aliovalent cation doping is conducted. Cation In3+, being p-type-doped, was chosen to substitute the Sn site (Sn4+) in Li2SnO3, and the photodegradation of 2,4-dichlorophenol was applied as a model reaction. Specifically, Li2Sn0.90In0.10O3 exhibited superior catalytic performance; the photodegradation efficiency reached about 100% within only 12 min. This efficiency is far greater than that of pure Li2SnO3 under identical conditions. Density functional theory calculations reveal that introducing In3+ increased the electron mobility, yet decreased the hole mobility, leading to photogenerated carrier separation. However, photoluminescence and time-resolved photoluminescence suggest that In3+ induced nonradiative coupling in the matrix, reducing the photogenerated carrier separation ratio compared with that of Li2SnO3. The optical band gap of Li2Sn0.90In0.10O3 was almost unchanged compared with that of Li2SnO3 via ultraviolet-visible absorption. The increased photocatalytic efficiency was ascribed to the lower valence band position and enhanced hole concentrations by valence band X-ray photoelectron spectroscopy and electrochemical measurements. Finally, a 2,4-dichlorophenol degradation pathway, an intermediate toxicity assessment, and a photocatalytic mechanism were proposed. This work offers insights into designing and optimizing semiconductor photocatalysts with high performance.

Synthesis and characterization of magnetically separable La1−x Bi x Cr1−y Fe y O3 and photocatalytic activity evaluation under visible light

A series of Bi and Fe doped La1−x Bi x Cr1−y Fe y O3 (x = 0.00–0.10 and y = 0.02–0.12) perovskites were fabricated through a facile microemulsion method and were characterized by XRD, DC electrical-resistivity, dielectric, VSM, and UV–Visible measurements. Orthorhombic phase of synthesized substituted chromite nanocrystallite was confirmed by powdered XRD analysis with crystallite size in 47.8–32.9 nm range. DC electrical resistivity was observed to increase from 1.70–39.99 × 108 Ω-cm. Dielectric parameters analyzed in frequency range of 20 kHz–20 MHz were decreased, while magnetic parameters were observed to increase with the increase in dopant (Bi+3 and Fe+3) concentration. Whereas coercivity values was low (narrow hysteresis loop), which indicate the soft ferromagnetic of the prepared material materials which are quite useful to employ in storage devices and electronics. Moreover, La1−x Bi x Cr1−y Fe y O3 degraded 90.80% Rhodamine B dye under visible light irradiation within 55 min. The increase in electrical resistivity, while decrease in dielectric parameters was also observed with increase in dopant concentration, ferromagnetic nature and excellent photocatalytic properties make this material suitable for high frequency energy devices, microwave appliances as well as an excellent magnetically separable photocatalyst for the purification of contaminated wastewater.

Enhanced photocatalytic efficiency of layered CdS/CdSe heterostructures: Insights from first principles electronic structure calculations

Metal sulfides are emerging as an important class of materials for photocatalytic applications, because of their high photo responsive nature in the wide visible light range. In this class of materials, CdS with a direct band gap of 2.4 eV, has gained special attention due to the relative position of its conduction band minimum, which is very close to the energies of the reduced protons. However, the photogenerated holes in the valence band of CdS are prone to oxidation and destroy its structure during photocatalysis. Thus constructing a CdS based heterostructure would be an effective strategy for improving the photocatalytic performance. In this work we have done a detail theoretical investigation based on hybrid density functional theory calculation to get insight into the energy band structure, mobility and charge transfer across the CdS/CdSe heterojunction. The results indicate that CdS/CdSe forms type-II heterostructure that has several advantages in improving the photocatalytic efficiency under visible light irradiation.

Novel P-n Li2SnO3/g-C3N4 Heterojunction With Enhanced Visible Light Photocatalytic Efficiency Toward Rhodamine B Degradation

The design of highly efficient and stable photocatalysts to utilize solar energy is a significant challenge in photocatalysis. In this work, a series of novel p-n heterojunction photocatalysts, Li₂SnO₃/g-C₃N₄, was successfully prepared via a facile calcining method, and exhibited superior photocatalytic activity toward the photodegradation of Rhodamine B solution under visible light irradiation as compared with pure Li₂SnO₃ and g-C₃N₄. The maximum kinetic rate constant of photocatalytic degradation of Rhodamine B within 60 min was 0.0302 min⁻¹, and the composites still retained excellent performance after four successive recycles. Chemical reactive species trapping experiments and electron paramagnetic resonance demonstrated that hydroxyl radicals (·OH) and superoxide ions (·O2-) were the dominant active species in the photocatalytic oxidation of Rhodamine B solution, while holes (h⁺) only played a minor role. We demonstrated that the enhancement of the photocatalytic activity could be assigned to the formation of a p-n junction photocatalytic system, which benefitted the efficient separation of photogenerated carriers. This study provides a visible light-responsive heterojunction photocatalyst with potential applications in environmental remediation.