Novel synthesis of PbBiO2Cl/BiOCl nanocomposite with enhanced visible-driven-light photocatalytic activity

Degradation of organic Pollutant by Using of BiVO4-NiFe2O4 Heterostructure Photocatalyst under Visible Light Irradiation: Assessment of Detoxicity Study Using Cirrhinus mrigala

The current study mainly concentrates on the photocatalytic activity of composite nanomaterial of BiVO4 (BVO), NiFe2O4 (NFO), and BiVO4-NiFe2O4 (BVO-NFO) under visible light. Among these, BVO-NFO composite degrades crystal violet dye within 60 min with a percentage degradation of 95.65% under visible light illumination. The BVO-NFO composite exhibits better photodegradation performance, which can be attributed to the effective light absorption and reduced recombination of the photoexcited charge carriers. Additionally, by applying a magnetic field, the BVO-NFO composite can be magnetically recovered by using the magnet for subsequent recycling. The synthesized composite was characterized using optical techniques like X-ray diffraction, ultraviolet diffuse reflectance spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, and energy dispersive X-ray analysis. The effect of dye, before and after degradation, on vital organs of fish species was examined such as fish gill (pulmonary-toxicity), fish liver (hepato-toxicity), fish kidney (renal toxicity), fish brain (neural toxicity), and fish muscle (myopathy). This work offers a clear and practical method for designing a highly crystalline semiconductor photocatalyst for dye degradation and the remediation of industrial wastewater.

Photocatalytic Degradation of Crystal Violet on Cu, Zn Doped BiVO4 Particles

Fabrication of codoped photocatalysts is a developing area of research. Herein, we explore the visible light photocatalytic properties of Cu, Zn codoped BiVO4 particles. Doping lower valent cations (Cu and Zn) makes the BiVO4 surface more acidic and enables us to target the basic crystal violet (CV) dye. The adopted hydrothermal protocol of synthesis results in the formation of Cu-Zn codoped monoclinic BiVO4 particles. Undoped monoclinic BiVO4, prepared by the same protocol, showed significant formation of oxygen vacancies. XPS analyses confirm the coexistence of Cu2+/Cu+ and Zn2+ dopants. Increased dopant percentage reduced oxygen vacancies. XRD indicates that Cu2+/Cu+ or Zn2+ dopants generally substitute Bi3+ in BiVO4. All photocatalysis activities for CV degradation are reported under near-neutral pH conditions. A typical codoped BiVO4 photocatalyst with 1% Zn and 2% Cu demonstrated the best CV degradation photocatalytic activity. The activity of this Zn, Cu codoped photocatalyst is better than that of pure, Zn-doped, and Cu-doped BiVO4 samples. Active species trapping experiments indicated the possible photocatalysis mechanism. The photocatalysts exhibited appropriate recyclability and photostability.

Optimization of Intercalated 2D BiOCl Sheets into Bi2WO6 Flowers for Photocatalytic NH3 Production and Antibiotic Pollutant Degradation

Photocatalytic N2 fixation is a complex reaction, thereby prompting researchers to design and analyze highly efficient materials. Herein, one-pot hydrothermal Bi2WO6-BiOCl (BW-BiOCl) heterojunctions were synthesized by varying the molar ratio of tungsten: chlorine precursor. Major morphological transformations in BiOCl were observed wherein it turned from thick sheets ∼230 nm in pure BiOCl to ∼30 nm in BW-BiOCl. This was accompanied by extensive growth of {001} facets verified from X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) analyses. A p-n heterojunction was formed between Bi2WO6 and BiOCl evidenced via photoluminescence (PL), time-resolved photoluminescence (TRPL), photocurrent response, and electrochemical impedance spectroscopy (EIS) analyses. The formation of heterojunction between Bi2WO6 and BiOCl led to the reduction of the work function in the BW-BiOCl 0.25 hybrid confirmed via ultraviolet photoelectron spectroscopy (UPS) analysis. BW-BiOCl 0.25 could produce ammonia up to 345.1 μmol·L-1·h-1 owing to the formation of a robust heterojunction with an S-scheme carrier transport mechanism. Recycle tests resulted in no loss in N2 reduction activities with post-catalytic analysis, showcasing the high stability of the synthesized heterojunction. Novel performance was owed to its excellent chemisorption of N2 gas on the heterojunction surface verified by N2-temperature programmed desorption (TPD). BW-BiOCl 0.25 also displayed a superior rate constant of 3.03 × 10-2 min-1 for 90 min CIP degradation time, higher than pristine BiOCl and Bi2WO6. Post-photocatalytic Fourier transform infrared (FTIR) spectroscopy of BW-BiOCl 0.25 revealed the presence of C-H stretching peaks in the range of 2850-2960 cm-1 due to adsorbed CIP and methanol species in CIP degradation and N2 fixation, respectively. This also confirmed the enhanced adsorption of reacting species onto the heterojunction surface.

Bismuth Oxychloride Nanomaterials Fighting for Human Health: From Photodegradation to Biomedical Applications

Environmental pollution and various diseases seriously affect the health of human beings. Photocatalytic nanomaterials (NMs) have been used for degrading pollution for a long time. However, the biomedical applications of photocatalytic NMs have only recently been investigated. As a typical photocatalytic NM, bismuth oxychloride (BiOCl) exhibits excellent photocatalytic performance due to its unique layered structure, electronic properties, optical properties, good photocatalytic activity, and stability. Some environmental pollutants, such as volatile organic compounds, antibiotics and their derivatives, heavy metal ions, pesticides, and microorganisms, could not only be detected but also be degraded by BiOCl-based NMs due to their excellent photocatalytic and photoelectrochemical properties. In particular, BiOCl-based NMs have been used as theranostic platforms because of their CT and photoacoustic imaging abilities, as well as photodynamic and photothermal performances. However, some reviews have only profiled the applications of dye degradation, hydrogen or oxygen production, carbon dioxide reduction, or nitrogen fixation of BiOCl NMs. There is a notable knowledge gap regarding the systematic study of the relationship between BiOCl NMs and human health, especially the biomedical applications of BiOCl-based NMs. As a result, in this review, the recent progress of BiOCl-based photocatalytic degradation and biomedical applications are summarized, and the improvement of BiOCl-based NMs in environmental and healthcare fields are also discussed. Finally, a few insights into the current status and future perspectives of BiOCl-based NMs are given.

Energizing periodic mesoporous organosilica (PMOS) with bismuth and cerium for photo-degrading methylene blue and methyl orange in water

This work reported an efficient catalyst to reduce the organic pollutants by using an energetic periodic mesoporous organosilica (PMOS) supported with bismuth (Bi-PMOS) and cerium (Ce-PMOS). PMOS support was designed through co-condensation of sodium silicate and 3-methacryloxypropyltrimethoxysilane on polysorbate templates. The resultant PMOSs were fabricated with bismuth and cerium oxides to formulate Bi-PMOS and Ce-PMOS, respectively. These materials showed photo-degradations of methylene blue (MB, 74.7% and 41.1% with Bi-PMOS and Ce-PMOS, respectively) and methyl orange (MO, 53.2% and 39.4% with Bi-PMOS and Ce-PMOS, respectively). Such efficient photo-degradations were attributed to the precise doping of metallic nodes of Bi₂ O₃ and CeO₂ on the porous structure of PMOS with high surface area. The results also showed that Bi and Ce were more effective in PMOS support for photo-degradation of dyes as the support provides more lifetime to photo-generated electron-hole pairs than other materials. Moreover, active reusability and high degradation efficiencies of Bi-PMOS and Ce-PMOS proved them better analytical tools to reduce organic pollutants under visible lights. PRACTITIONER POINTS: The oxides of bismuth and cerium have impressive photocatalytic characteristics. New material energizing mesoporous organosilica with bismuth and cerium for photo-degradation of methylene blue and methyl orange in water. The use of an efficient catalyst to reduce the organic pollutants by using an energetic periodic mesoporous organosilica (PMOS) supported with bismuth (Bi-PMOS) and cerium (Ce-PMOS).

Visible-light-driven photocatalysis of carbon dioxide and organic pollutants by MFeO2 (M = Li, Na, or K)

In recent years, lithium-containing ceramic materials have attracted considerable research attention as high-temperature adsorbents of carbon dioxide. The recycling of electrode materials from spent lithium-ion batteries for use as photocatalysts in recovering CO₂ and degrading organic pollutants is worthy of exploration. Solid, magnetic ferrite-containing photocatalysts are easily separated from reaction solutions by using magnetic devices. Solid catalysts (e.g., LiFeO₂, LiFe₅O₈, NaFeO₂, and K₂Fe₂O₄) were prepared through the calcination of Fe₂O₃ and M₂CO₃. CO₂ was photoreduced and crystal violet (CV) and 2-hydroxybenzoic acid (2-HBA) were photodegraded under visible light irradiation. The optimized K₂Fe₂O₄ photocatalyst increased the rate of photocatalytic conversion from CO₂ to methane at 20.9 µmol g^-1 h^-1. The catalytic efficiency indicated that the optimized reaction rate constants of CV with LiFeO₂, NaFeO₂, and K₂Fe₂O₄ were 2.98 × 10^-1, 5.32 × 10^-1, and 4.36 × 10^-1 h^-1, respectively. The quenching effect achieved through the use of various scavengers and the electron paramagnetic resonance in CV degradation revealed the substantial contribution of the reactive superoxide anion radical O₂^- and the minor roles of h⁺ and the OH radical. Its usefulness in the synthesis of solid-base catalyst MFeO₂ is promising for environmental control and relevant applications, particularly in solar energy manufacturing.

In situ preparation of g-C3N4/Bi4O5I2 complex and its elevated photoactivity in Methyl Orange degradation under visible light

A graphite carbon nitride (g-C₃N₄) modified Bi₄O₅I₂ composite was successfully prepared in-situ via the thermal treatment of a g-C₃N₄/BiOI precursor at 400°C for 3 hr. The as-prepared g-C₃N₄/Bi₄O₅I₂ showed high photocatalytic performance in Methyl Orange (MO) degradation under visible light. The best sample presented a degradation rate of 0.164 min^-1, which is 3.2 and 82 times as high as that of Bi₄O₅I₂ and g-C₃N₄, respectively. The g-C₃N₄/Bi₄O₅I₂ was characterized by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectra (DRS), electrochemical impedance spectroscopy (EIS) and transient photocurrent response in order to explain the enhanced photoactivity. Results indicated that the decoration with a small amount of g-C₃N₄ influenced the specific surface area only slightly. Nevertheless, the capability for absorbing visible light was improved measurably, which was beneficial to the MO degradation. On top of that, a strong interaction between g-C₃N₄ and Bi₄O₅I₂ was detected. This interplay promoted the formation of a favorable heterojunction structure and thereby enhanced the charge separation. Thus, the g-C₃N₄/Bi₄O₅I₂ composite presented greater charge separation efficiency and much better photocatalytic performance than Bi₄O₅I₂. Additionally, g-C₃N₄/Bi₄O₅I₂ also presented high stability. •O₂^- and holes were verified to be the main reactive species.

Bi4O5I2/nitrogen-doped hierarchical carbon (NHC) composites with tremella-like structure for high photocatalytic performance

BiOI is a visible photocatalyst towards organic pollutant. In this work, biomass waste (withered typha grass) was used to fabricate nitrogen-doped hierarchical carbon (NHC) by an one-step carbonization route. Then NHC provided a good carrier to load the BiOI semiconductor materials by a green simple co-precipitation method, after adding NaOH solution, the irregular microspheres BiOI/NHC was gradually etched by OH^- to form the tremella-like Bi₄O₅I₂/NHC. The well-defined tremella-like Bi₄O₅I₂/NHC invested adequate interface and high particular surface range (S_BET: 66 m² g^-1), which is higher than pure BiOI (22 m² g^-1) and Bi₄O₅I₂ (17 m² g^-1). Multiple synergistic effects, such as high S_BET can give more dynamic destinations, the special tremella-like structure can assimilate more reflected occurrence light of other nanosheets, low I content can increase the conduction/valence band gap of semiconductor materials and NHC can act as an electron acceptor, making as-prepared Bi₄O₅I₂/NHC composite ideal candidates for photocatalysis. The degradation rate of Bi₄O₅I₂/NHC reaches up to 87.4% of methyl orange in 2 h, which is about 2 times higher than BiOI and Bi₄O₅I₂. Therefore, this work gives a technique to link NHC derived from biomass waste to Bi₄O₅I₂ with highly-efficiency photocatalytic performance.

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.

BiOCl facilitated photocatalytic degradation of atenolol from water: Reaction kinetics, pathways and products

Atenolol (ATL), a kind of largely used beta-blockers, has been widely detected in the aquatic environment, which could cause adverse impact on human beings. In this study, bismuth oxychloride (BiOCl) photocatalyst was synthesized and applied to remove ATL in the aqueous system under simulated natural light. Emphasis was laid on the reaction kinetics and the impact of natural organic matter (NOM) (0-20 mg/L). Possible transformation pathways were systematically investigated based on identification of reaction products via liquid chromatography-mass spectrometry (LC-MS). As a consequence, BiOCl presents highly photocatalytic efficiency yielding up to nearly 100% ATL conversion after 60 min of interaction, together with fairly high photostability evidenced by considerably efficient removal of ATL after 10 catalytic cycles. Four kinds of possible products are detected using LC-MS in the process of reaction, indicating possible transformation ways of ATL photocatalysis. NOM has an inhibiting impact on the removal of ATL and influences the products distribution. This study provides an emerging nanocatalyst for ATL photodegradation and could eventually lead to development of novel methods to control pharmaceutical contamination in water.

Crystal violet and toxicity removal by adsorption and simultaneous photocatalysis in a continuous flow micro-reactor

A continuous flow micro-reactor irradiated by UV-LEDs was employed to treat coloured wastewater by adsorption and simultaneous photocatalysis. Zinc oxide (ZnO) immobilized on commercial zeolites pellets in spherical shape (ZEO) was used as catalytic material in a micro-reactor maximizing the photocatalyst exposition to light sources, irradiating uniformly the entire solution volume and improving the mass transfer phenomena. Experimental tests were carried out on crystal violet dye (CV) as one of the main dying agent present in textile wastewater. The comparison between adsorption and adsorption/photocatalytic tests showed that UV irradiation can achieve a steady state CV concentration value corresponding to an equilibrium condition between adsorption and photocatalytic oxidation. The higher removal efficiency (i.e. 93%) was observed with a liquid flow rate of 1.1 mL/min (contact time = 4.7 min; CV = 10 mg/L) under UV light irradiation. In the steady state, CV removal remained constant for the overall testing time. Bioassays evidenced that toxicity was not completely removed (i.e. final effluent ranked as "slight acute toxic") from wastewater suggesting its suitability for sewage collection discharge. A Dubinin Radushkevich (D-R) isotherm model was applied for studying the adsorption behaviour of ZnO/ZEO sample. CV adsorption constants were evaluated from experimental data carried out in dark conditions in a batch system. Kinetic expression of CV removal and the D-R adsorption were incorporated in the CV mass balance estimating the kinetic parameter. The model was validated comparing the calculated CV conversion with the experimental tests collected at different CV inlet concentration.

Photochemical degradation of trypan blue

Purpose

To investigate the photochemical degradation of trypan blue (TB) and to identify decomposition products.

Methods

Defined solution samples of TB and a mixture with lutein/zeaxanthin were exposed to blue light. Thermal degradation processes were ruled out using controls not subjected to irradiation. All samples were analyzed using optical microscopy, UV/Vis spectroscopy, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and nuclear magnetic resonance (NMR) spectrometry. Degradation kinetics were determined based on changes in absorbance; intermediates were identified by analyzing mass differences of characteristic fragment ion peaks within the fragmentation patterns, and assignments were verified by NMR.

Results

TB demonstrated a photochemical degradation, which can be triggered by lutein/zeaxanthin. Intermediates vary depending on the presence of lutein/zeaxanthin. The self-sensitized photodegradation of TB occurs under generation of dimethyl sulfate and presumed formation of phenol. In contrast, within the presence of lutein/zeaxanthin the decomposition of TB indicates the formation of methoxyamine and sulfonyl arin. Thermal degradation processes were not observed.

Conclusions

TB demonstrated a photodegradation that may be triggered by lutein/zeaxanthin and results in the formation of cytotoxic decomposition products. Our findings contribute to understand degradation mechanisms of TB and may elucidate previous clinical and experimental observations of cellular toxicity after TB application.

Synthesis of Zn3(VO4)2/BiVO4 heterojunction composite for the photocatalytic degradation of methylene blue organic dye and electrochemical detection of H2O2

In this study, a Zn₃(VO₄)₂/BiVO₄ heterojunction nanocomposite photocatalyst was prepared using a hydrothermal route with different molar concentration ratios.

Visible light assisted photocatalytic degradation of crystal violet dye and electrochemical detection of ascorbic acid using a BiVO4/FeVO4 heterojunction composite

A highly pure BiVO₄/FeVO₄ heterojunction nanocomposite photocatalyst was synthesized by a facile hydrothermal method. The simple and economical manufacturing process allows easier industrial scale-up and the results contribute to the design of more effective photocatalysts.