Hydrothermally derived Cr-doped SnO2 nanoflakes for enhanced photocatalytic and photoelectrochemical water oxidation performance under visible light irradiation

Green synthesis of novel Zn0.5Ni0.5FeCrO4 spinel magnetic nanoparticles: Photodegradation of 4-nitrophenol and aniline under visible light irradiation

This study explores novel nanoparticles used in environmental remediation of 4-nitrophenol and aniline from wastewater bodies. The Zn0.5Ni0.5FeCrO4 magnetic nanoparticles (MNPs) were synthesized using tragacanth gel as a green, low-cost, and easy sol-gel method. The MNPs were characterized by XRD, XPS, FT-IR, VSM, TEM, EDX, FESEM, BET, DRS, and elemental mapping. The analysis demonstrated that nanoparticles have a spinel cubic structure, spatial distribution of the elements, ferromagnetic activity, narrow bandgap, and uniform morphology. Furthermore, effectiveness of the developed MNPs to degrade recalcitrant organic pollutants such as 4-nitrophenol (4-NP) and aniline under visible light exposure were studied. The results indicated 95% aniline and 80% of 4-NP were successfully degraded in 180 and 150 min, respectively. The total organic carbon (TOC) analysis revealed 65% and 54% removal of aniline and 4-NP. LC-MS was employed to elucidate the photodegradation mechanism and to identify the degradation products, including small fragmented molecules.

Controlled solvothermal synthesis of self-assembled SrTiO3 microstructures for expeditious solar-driven photocatalysis dye effluents degradation

In this work, the self-assembled SrTiO3 (STO) microstructures were synthesized via a facile one-step solvothermal method. As the solvothermal temperature increased from 140 °C to 200 °C, the STO changed from a flower-like architecture to finally an irregularly aggregated flake-like morphology. The photocatalytic performance of as-synthesized samples was assessed through the degradation of rhodamine B (RhB) and malachite green (MG) under simulated solar irradiation. The results indicated that the photocatalytic performance of STO samples depended on their morphology, in which the hierarchical flower-like STO synthesized at 160 °C demonstrated the highest photoactivities. The photocatalytic enhancement of STO-160 was benefited from its large surface area and mesoporous configuration, hence facilitating the presence of more reactive species and accelerating the charge separation. Moreover, the real-world practicality of STO-160 photocatalysis was examined via the real printed ink wastewater-containing RhB and MG treatment. The phytotoxicity analyses demonstrated that the photocatalytically treated wastewater increased the germination of mung bean seeds, and the good reusability of synthesized STO-160 in photodegradation reaction also promoted its application in practical scenarios. This work highlights the promising potential of tailored STO microstructures for effective environmental remediation applications.

Visible light photocatalytic NOx removal with suppressed poisonous NO2 byproduct generation over simply synthesized triangular silver nanoparticles coupled with tin dioxide

The treatment or conversion of air pollutants with a low generation of secondary toxic substances has become a hot topic in indoor air pollution abatement. Herein, we used triangle-shaped Ag nanoparticles coupled with SnO2 for efficient photocatalytic NO removal. Ag triangular nanoparticles (TNPs) were synthesized by the photoreduction method and SnO2 was coupled by a simple chemical impregnation process. The photocatalytic NO removal activity results show that the modification with Ag TNPs significantly boosted the removal performance up to 3.4 times higher than pristine SnO2. The underlying roles of Ag TNPs in NO removal activity improvement are due to some advantages of Ag TNPs. Moreover, the Ag TNPs contributed photogenerated holes as the main active species toward enhancing the NO oxidation reaction. In particular, the selectivity toward green products significantly improved from 52.78% (SnO2) to 86.99% (Ag TNPs/SnO2). The formation of reactive radicals under light irradiation was also verified by DMPO spin-trapping experiments. This work provides a potential candidate for visible-light photocatalytic NO removal with low toxic byproduct generation.

Efficient synthesis of 3D ZnO nanostructures on ITO surfaces for enhanced photoelectrochemical water splitting

New photoactive materials with uniform and well-defined morphologies were developed for efficient and sustainable photoelectrochemical (PEC) water splitting and hydrogen production. The investigation is focused on hydrothermal deposition of zinc oxide (ZnO) onto indium tin oxide (ITO) conductive surfaces and optimization of hydrothermal temperature for growing uniform sized 3D ZnO morphologies. Fine-tuning of hydrothermal temperature enhanced the scalability, efficiency, and performance of ZnO-decorated ITO electrodes used in PEC water splitting. Under UV light irradiation and using eco-friendly low-cost hydrothermal process in the presence of stable ZnO offered uniform 3D ZnO, which exhibited a high photocurrent of 0.6 mA/cm2 having stability up to 5 h under light-on and light-off conditions. The impact of hydrothermal temperature on the morphological properties of the deposited ZnO and its subsequent performance in PEC water splitting was investigated. The work contributes to advancement of scalable and efficient fabrication technique for developing energy converting photoactive materials.

Imperfect makes perfect: defect engineering of photoelectrodes towards efficient photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting for hydrogen evolution has been considered as a promising technology to solve the energy and environmental issues. However, the solar-to-hydrogen (STH) conversion efficiencies of current PEC systems are far from meeting the commercial demand (10%) due to the lack of efficient photoelectrode materials. The recent rapid development of defect engineering of photoelectrodes has significantly improved the PEC performance, which is expected to break through the bottleneck of low STH efficiency. In this review, the category and the construction methods of different defects in photoelectrode materials are summarized. Based on the in-depth summary and analysis of existing reports, the PEC performance enhancement mechanism of defect engineering is critically discussed in terms of light absorption, carrier separation and transport, and surface redox reactions. Finally, the application prospects and challenges of defect engineering for PEC water splitting are presented, and the future research directions in this field are also proposed.

Recent advances in sustainable N-heterocyclic carbene-Pd(II)-pyridine (PEPPSI) catalysts: A review

Various catalysts in homogeneous or heterogeneous catalysis deploy unconventional reaction pathways by lowering the activation energy (AE) barrier, controlling the selectivity, and creating environmental impact, thereby bringing about economic viability. Hence, the study of these methodologies is of immense interest. To develop a new chemistry, there is much scope for the invention of brilliant candidates that could effectively catalyze diverse reaction methodologies. The palladium-catalyzed reactions motivate interesting applications on various organic transformations under mild reaction conditions. Although phosphorous designed ligands or catalysts have been used, despite their expensiveness, sensitivity and other properties, there is the necessity of developing even better cross-coupling ligands or catalysts such as N-heterocyclic carbene (NHC)-based palladium complexes. These palladium-NHCs (Pd-NHC) are novel and universal nucleophilic entities that have come into light as the most successful class of catalysts in organometallic chemistry. In the same class, a specific category of palladium-NHCs such as palladium-pyridine enhanced pre-catalyst preparation by the stabilization initiation (palladium-PEPPSI) complexes, are emerging as versatile alternatives to phosphine containing palladium complexes for various cross-coupling reactions due to their excellent catalytic activity. Further to mention that NHCs are recently extensively used as ancillary ligands in organometallic chemistry, which includes industrial-related catalytic transformations due to strong σ-donors to metal centres. Apart from this, many NHC-metal complexes are the fascinating consideration in material science as probable metallo-pharmaceuticals. The current review offers a brief exploration of palladium-PEPPSI complexes over the past few years. Further, the synthesis of a variety of these types of catalysts, their applications in Suzuki-Miyaura, Buchwald-Hartwig, Sonogashira, Negishi couplings direct C2-arylation, O-C(O) cleavage, α-arylation/alkylation of carbonyl compounds and trans-amidation reactions via cross-coupling methodologies, which are covered. Additionally, reported recent developments on reusable heterogeneous PdPEPPSI complexes and their catalytic applications are being covered. Finally, the chiral Pd complexes and their asymmetric transformations are discussed.