Wide spectral response photothermal catalysis-fenton coupling systems with 3D hierarchical Fe3O4/Ag/Bi2MoO6 ternary hetero-superstructural magnetic microspheres for efficient high-toxic organic pollutants removal

Magnetic Dendritic Polymer Nanospheres for High-Performance Separation of Histidine-Rich Proteins

Magnetic nanospheres are becoming a promising platform for a wide range of applications in pharmacy, life science, and immunodiagnostics due to their high surface area, ease of synthesis and manipulation, fast separation, good biocompatibility, and recyclable performance. In this work, an innovative and efficient method is developed by in situ reducing and growing Ni(OH)₂ for the preparation of dendritic mesoporous nanocomposites of silica@Fe₃O₄/tannic acid@nickel hydroxide (dSiO₂@Fe₃O₄/TA@Ni(OH)₂). The flower-like nanospheres have good magnetic response, large surface area, and high histidine-rich protein (His-protein) purification performance. The dSiO₂@Fe₃O₄/TA@Ni(OH)₂ nanospheres were synthesized on the basis of a φ(NaSal/CTAB) of 1/1 and a mass of ferrous chloride tetrahydrate of 0.3 g, resulting in a saturation magnetization value of 48.21 emu/g, which means it can be collected within ∼1 min using a magnetic stand. Also, the BET test showed that the surface area is 92.47 m²/g and the pore size is ∼3.9 nm for dSiO₂@Fe₃O₄/TA@Ni(OH)₂ nanocomposites. Notably, the nickel hydroxide with unique flower-like structural features enables the combination of a large number of Ni²⁺ ions and His-proteins for high performance. The isolation and purification experiments of the synthesized dSiO₂@Fe₃O₄/TA@Ni(OH)₂ were performed by separating His-proteins from a matrix composed of bovine hemoglobin (BHb), bovine serum albumin (BSA), and lysozyme (LYZ). The result showed that the nanospheres have a high combination capacity of ∼1880 mg/g in a rapid equilibrium time of 20 min, which was selective for the adsorption of BHb. In addition, the stability and recyclability of BHb are 80% after seven cycles. Furthermore, the nanospheres were also used to isolate His-proteins from fetal bovine serum, proving its utility. Therefore, the strategy of separating and purifying His-proteins using dSiO₂@Fe₃O₄/TA@Ni(OH)₂ nanospheres is promising for practical applications.

Temperature, Doping, and Chemical Potential Tuning Intrinsic Defects Concentration in Bi2MoO6: GGA + U Method

Using the GGA + U method, the formation energy and concentration of intrinsic defects in Bi₂MoO₆ are explored under different chemical conditions, with/without doping, from 120 to 900 K. We find that the intrinsic defect and carrier concentration can be deduced from the small range of calculated Fermi levels in the diagram of formation energy vs Fermi level under different conditions. Once the doping conditions or/and temperature are determined, the corresponding E_F is only limited to a special region in the diagram of formation energy vs Fermi level, from which the magnitude relationship of defects concentration can be directly derived from their formation energy. The lower the defect formation energy is, the higher the defect concentration is. With E_F moving under different doping conditions, the intrinsic defect concentration changes accordingly. At the same time, the highest electron concentration at the relative O-poor (point H_U) with only intrinsic defects confirms its intrinsic n-type behavior. Moreover, upon A^-/D⁺ doping, E_F moves closer to VBM/CBM for the increasing concentration of holes/electrons. The electron concentration can also be further improved after D⁺ doping, indicating that D⁺ doping under O-poor chemical growth conditions is positive to improve its photogenerated carriers. This provides us with a method to adjust the intrinsic defect concentration and deepens our knowledge about comprehension and application of the diagram of formation energy vs Fermi level.

Olive Mill Wastewater Remediation: From Conventional Approaches to Photocatalytic Processes by Easily Recoverable Materials

Olive oil production in Mediterranean countries represents a crucial market, especially for Spain, Italy, and Greece. However, although this sector plays a significant role in the European economy, it also leads to dramatic environmental consequences. Waste generated from olive oil production processes can be divided into solid waste and olive mill wastewaters (OMWW). These latter are characterized by high levels of organic compounds (i.e., polyphenols) that have been efficiently removed because of their hazardous environmental effects. Over the years, in this regard, several strategies have been primarily investigated, but all of them are characterized by advantages and weaknesses, which need to be overcome. Moreover, in recent years, each country has developed national legislation to regulate this type of waste, in line with the EU legislation. In this scenario, the present review provides an insight into the different methods used for treating olive mill wastewaters paying particular attention to the recent advances related to the development of more efficient photocatalytic approaches. In this regard, the most advanced photocatalysts should also be easily recoverable and considered valid alternatives to the currently used conventional systems. In this context, the optimization of innovative systems is today’s object of hard work by the research community due to the profound potential they can offer in real applications. This review provides an overview of OMWW treatment methods, highlighting advantages and disadvantages and discussing the still unresolved critical issues.

A review on hierarchical Bi2MoO6 nanostructures for photocatalysis applications

This overview provides comprehensive understanding and development trends of hierarchical Bi2MoO6 nanostructures as photocatalysts for efficient photocatalysis applications.

Construction of a novel step-scheme CdS/Pt/Bi2MoO6 photocatalyst for efficient photocatalytic fuel denitrification

Construction of step-scheme (S-scheme) heterojunction (HJ) structures is an excellent strategy to achieve efficient photogenerated carrier separation and retain strong redox ability. Recently, the development of efficient S-scheme HJ photocatalysts for the degradation of environmental organic pollutants has attracted considerable attention. In this work, a novel S-scheme CdS/Pt/Bi2MoO6 (CPB) photocatalyst was prepared for the first time by sonochemical and solvothermal methods. By anchoring Pt nanoparticles (NPs) at the interface between CdS nanorods (NRs) and Bi2MoO6 nanosheets (NSs), the migration of photogenerated electron-hole pairs along the stepped path was achieved. The ternary CPB samples were characterized by various analytical techniques, and their photocatalytic performance was investigated by conducting simulated fuel denitrification under visible-light irradiation. It was found that the CPB-4 composites exhibited the highest pyridine degradation activity, which reached 94% after 4 h of visible-light irradiation. The superior photocatalytic performance of the CPB-4 composite could be attributed to the synergistic effect of the Pt NPs and Bi2MoO6 NRs on the photocatalytic degradation as well as to the introduction of Pt and Bi2MoO6, which led to an excellent response and large specific surface area of the CPB-4 composite. Lastly, the bridging role of the Pt NPs introduced into the S-scheme system was also notable, as it effectively improved the separation and transfer of the CdS/Bi2MoO6 interfaces for the photogenerated electron-hole pairs while retaining strong redox ability.

Near-Infrared-Responsive Photocatalysts

Broadening the absorption of light to the near-infrared (NIR) region is important in photocatalysis to achieve efficient solar-to-fuel conversion. NIR-responsive photocatalysts that can utilize diffusive solar energy are attractive for alleviating the energy crisis and environmental pollution. Over the past few years, considerable progress on the component and structural design of NIR-responsive photocatalysts have been reported. This study aims to systematically summarize recent progress toward the material design and mechanism optimization of NIR-responsive photocatalysts in this area. Depending on the main strategies for harvesting NIR photons, NIR-responsive photocatalysts can be categorized as direct NIR-light photocatalysts, indirect NIR-light photocatalysts, and photothermal photocatalysts. Furthermore, the construction and application of different NIR-responsive photocatalytic systems are summarized. Conclusions and perspectives are presented to further explore the potential of NIR-responsive photocatalysts in this field.

Zinc sulfide quantum dots/zinc oxide nanospheres/bismuth-enriched bismuth oxyiodides as Z-scheme/type-II tandem heterojunctions for an efficient charge separation and boost solar-driven photocatalytic performance

A novel zinc sulfide quantum dot (ZnS QD)/zinc oxide (ZnO) nanosphere/bismuth-enriched bismuth oxyiodide (Bi₄O₅I₂) tandem heterojunction photocatalyst is fabricated through two-step solvothermal, calcination and one-step hydrothermal strategies. The successfully constructed core-shell nanostructure can increase the interface area and the active sites of the composite photocatalysts. The formation of a Z-scheme/Type-II tandem heterojunction favors the transfer and spatial separation of charge carriers, in which Bi₄O₅I₂ plays a bridging role to connect ZnO and ZnS. Simultaneously, the participation of Bi₄O₅I₂ significantly shortens the band gap of the composite photocatalyst. This dual functional ZnO@Bi₄O₅I₂/ZnS composite photocatalyst has a high photocatalytic hydrogen evolution rate of 578.4 µmol g^-1h^-1 and an excellent photocatalytic degradation efficiency for bisphenol A (BPA) and 2,4,5-trichlorophenol (TCP). In addition, cycling tests show that ZnO@Bi₄O₅I₂/ZnS has a high stability, which is favorable for practical applications. This novel ZnO@Bi₄O₅I₂/ZnS Z-scheme/Type-II tandem heterojunction photocatalyst will provide new ideas for the multichannel charge transfer of other highly efficient heterojunction photocatalysts.

A 2D/2D S-scheme photo-Fenton catalyst based on ultrathin Bi2MoO6 and Fe2O3 hexagonal nanosheets for efficient tetracycline degradation

Fe₂O₃/Bi₂MoO₆ heterojunctions exhibit an observably improved photo-Fenton catalytic tetracycline degradation activity, which is accredited to an 2D/2D S-scheme charge transfer mechanism.

One-Step Synthesis of Hierarchical Flower-like SnO2/BiOCOOH Microspheres with Enhanced Light Response for the Removal of Pollutants

The low separation rate of electron-hole pairs in single-component photocatalysts severely limits their applications for wastewater treatment. For this study, SnO₂/BiOCOOH photocatalysts in flower-like microspheres were controllably synthesized via a one-step hydrothermal method and were characterized by various advanced techniques. These SnO₂/BiOCOOH nanocomposites demonstrated excellent photocatalytic activities for the degradation of rhodamine B (RhB), titan yellow, and levofloxacin hydrochloride (LVF). Specifically, 98.5% of RhB, 80% of titan yellow, and 85% of LVF were degraded under 5 W LED (λ = 365 nm) light irradiation within 30, 40, and 60 min, respectively. Radical trapping experiments and electron spin resonance results indicated that h⁺ was the dominant active radical, whereas ·O₂^- and ·OH played an auxiliary role in the photocatalytic system. Subsequently, a potential photocatalytic mechanism was proposed based on the experimental results.

Promoted spatial charge separation of plasmon Ag and co-catalyst Co x P decorated mesoporous g-C3N4 nanosheet assembly for unexpected solar-driven photocatalytic performance

Plasmon Ag and co-catalyst Co _x P decorated mesoporous graphite carbon nitride nanosheet assemblies have been synthesized via a template-calcination and ball milling strategy combined with photoreduction. The obtained composites are characterized by x-ray diffraction, Fourier transmission infrared spectroscopy, x-ray photoelectron spectroscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectroscopy. The results show that the sample assembly with mesoporous structure has specific surface area of 50.4 m² g^-1, pore size of 11.3 nm and pore volume of 0.21 cm³ g^-1. The Ag and Co _x P nanoparticles are decorated on the surface of graphite carbon nitride uniformly. Under solar light irradiation, the photocatalytic degradation rate of ceftazidime for the prepared sample assembly is up to ∼92%, and the photocatalytic reaction rate constant is about 10 times higher than that of bare graphite carbon nitride. Moreover, the sample assembly also exhibits a solar-driven photocatalytic hydrogen production rate of 96.66 μmol g^-1 h^-1. It can attributed to the surface plasmon resonance effect of Ag nanoparticles and Co _x P co-catalyst promoting the spatial charge separation and the mesoporous structure providing more surface active sites and favoring mass transfer. This special structure offers new insights for fabricating other high-performance photocatalysts with high spatial charge separation.

Nano-zero-valent iron and MnOx selective deposition on BiVO4 decahedron superstructures for promoted spatial charge separation and exceptional catalytic activity in visible-light-driven photocatalysis-Fenton coupling system

Novel nano-zero-valent iron (Fe⁰)/MnO_x/BiVO₄ ternary magnetic assemblies are fabricated through hydrothermal and photo-deposition strategy. The assemblies are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. Fe⁰ as a reduction cocatalyst are deposited on surface of monoclinic BiVO₄ decahedron supersturcture. Meanwhile, MnO_x as an oxidation cocatalyst is selectively anchored on oxidative {110} facet of BiVO₄ by photodeposition. The photogenerated electrons and holes can be transmitted to Fe⁰ and MnO_x, respectively, which favors the spatial charge separation. The adjunction of Fe⁰ significantly enhances light absorption, and forms a photocatalysis-Fenton coupling system simultaneously. The assemblies with narrow band gap of 2.10 eV display an exceptional photocatalytic activity, and the visible-light-driven photocatalytic degradation ratio of 2,4-dichlorophenol and Bisphenol A are up to 95.4 and 91.4%, respectively, which are several times higher than that of pristine BiVO₄. This is ascribed to the selective decoration of Fe⁰ and MnOx favoring the spatial charge separation, and the photocatalysis-Fenton coupling system enhancing degradation. Moreover, the superior magnetic property due to Fe⁰ decoration realizes magnetic separation of catalysts, which is favorable in practical applications.

Surface-defect-rich mesoporous NH2-MIL-125 (Ti)@Bi2MoO6 core-shell heterojunction with improved charge separation and enhanced visible-light-driven photocatalytic performance

Mesoporous NH₂-MIL-125(Ti)@Bi₂MoO₆ core-shell heterojunctions with surface defects were fabricated through a facile solvothermal method. The mesoporous core-shell structure with a large relative surface area of 87.7 m² g^-1 and narrow pore size of 8.2 nm extends the photoresponse to the range of visible light due to the narrow band gap of ∼1.89 eV. The visible-light-driven photocatalytic degradation efficiency of highly toxic dichlorophen and trichlorophenol were 93.28 and 92.19%, respectively, and the corresponding rate constants were approximately 8 and 17 times higher than the rates achieved by pristine NH₂-MIL-125(Ti). The photocatalytic oxygen production rate was increased to 171.3 µmol g^-1. Recycling for several cycles indicates high stability, which is favorable for practical applications. The excellent photocatalytic performance can be ascribed to the formation of the core-shell heterojunctions and to the surface defects that favor charge separation and visible light absorption; the mesoporous structure offers an adequate number of surface active sites and mass transfer. This novel mesoporous core-shell photocatalyst will have potential applications in the environment, and this strategy offers a new insight into fabrication of other high-performance core-shell structure photocatalysts.

Modulation of Bi2 MoO6 -Based Materials for Photocatalytic Water Splitting and Environmental Application: a Critical Review

Highly active photocatalysts driving chemical reactions are of paramount importance toward renewable energy substitutes and environmental protection. As a fascinating Aurivillius phase material, Bi₂ MoO₆ has been the hotspot in photocatalytic applications due to its visible light absorption, nontoxicity, low cost, and high chemical durability. However, pure Bi₂ MoO₆ suffers from low efficiency in separating photogenerated carriers, small surface area, and poor quantum yield, resulting in low photocatalytic activity. Various strategies, such as morphology control, doping/defect-introduction, metal deposition, semiconductor combination, and surface modification with conjugative π structures, have been systematically explored to improve the photocatalytic activity of Bi₂ MoO₆ . To accelerate further developments of Bi₂ MoO₆ in the field of photocatalysis, this comprehensive Review endeavors to summarize recent research progress for the construction of highly efficient Bi₂ MoO₆ -based photocatalysts. Furthermore, benefiting from the enhanced photocatalytic activity of Bi₂ MoO₆ -based materials, various photocatalytic applications including water splitting, pollutant removal, and disinfection of bacteria, were introduced and critically reviewed. Finally, the current challenges and prospects of Bi₂ MoO₆ are pointed out. This comprehensive Review is expected to consolidate the existing fundamental theories of photocatalysis and pave a novel avenue to rationally design highly efficient Bi₂ MoO₆ -based photocatalysts for environmental pollution control and green energy development.

Multifunctional magnetic sphere-MoS2@Au hybrid for surface-enhanced Raman scattering detection and visible light photo-Fenton degradation of aromatic dyes

A ternary hybrid, MNPs-MoS₂@Au, composed of gold nanoparticles (AuNPs) grown on a magnetic sphere (MNPs)-MoS₂ microflower composite (MNPs-MoS₂) was proposed for surface-enhanced Raman scattering (SERS) detection and visible-light photo-Fenton degradation of aromatic dyes. The hybrid was prepared by sequential solvothermal growth of MNPs and MoS₂, and electroless deposition of AuNPs. A comparison of results revealed that the synergy among these components endowed the hybrid with a much higher SERS enhancement ability than MNPs, or MNPs@MoS₂. The dosage of HAuCl₄ and MNPs-MoS₂ to prepare the hybrid greatly influenced the SERS activity of the hybrid. Under optimized conditions, quantitative SERS analysis of dyes including CV, MG, and MB was performed with a low detection limit (1 pM, 0.15 nM and 1 nM for CV, MG, and MB, respectively) and adequate reproducibility (RSDs were less than 6% and 11% for CV and MG, respectively). The hybrid could also serve as a visible light-active photo-Fenton catalyst for efficient degradation of aromatic dyes, and the decolorization of 20 mg/L RhB was 90% in 40 min in the presence of H₂O₂ because of a synergy mechanism among components confirmed by comparison experiment and first-order kinetics study. The multifunctional material prepared here possesses great values in SERS analysis, environmental monitoring, and restoration.