Enhanced photocatalytic activity of 3D hierarchical RP/BP/BiOCOOH via oxygen vacancies and double heterojunctions

Visible light photocatalytic degradation of oxytetracycline hydrochloride using chitosan-loaded Z-scheme heterostructured material BiOCOOH/O-gC3N4

In this work, a Z-scheme heterostructured BiOCOOH/O-gC3N4 material was synthesized and immobilized on chitosan (CTS) to obtain the BiOCOOH/O-gC3N4/CTS photocatalytic material for photocatalytic degradation of oxytetracycline hydrochloride (CTC).Our findings indicate that the composite material BiOCOOH/O-gC3N4, as well as the BiOCOOH/O-gC3N4/CTS composite membrane, displayed a significantly higher efficiency in photocatalytic degradation of CTC compared to BiOCOOH alone, owing to the synergistic effect of adsorption and photocatalysis. Following four cycles of use, the composite material retained around 96 % of its initial photocatalytic degradation activity. The addition of CTS in the photocatalytic material resolved issues such as aggregation and difficult recovery commonly encountered with powder materials, thereby facilitating effective collision between the photocatalytic active sites and CTC. Experimental and theoretical calculations provided confirmation that the combination of BiOCOOH and O-gC3N4 effectively enhanced the light absorption capacity and photocatalytic performance. Furthermore, we investigated the influence of environmental factors such as pH value and anions on the photocatalytic degradation experiment, which offers valuable insights for the application of composite catalysts in wastewater treatment.

Fenton-like Degradation of Methylene Blue on Attapulgite Clay Composite by Loading of Iron-Oxide: Eco-Friendly Preparation and Its Catalytic Activity

The continuous discharge of organic dyes into freshwater resources poses a long-term hazard to aquatic life. The advanced oxidation Fenton process is a combo of adsorption and degradation of pollutants to detoxify toxic effluents, such as anti-bacterial drugs, antibiotics, and organic dyes. In this work, an activated attapulgite clay-loaded iron-oxide (A-ATP@Fe3O4) was produced using a two-step reaction, in which attapulgite serves as an enrichment matrix and Fe3O4 functions as the active degrading component. The maximum adsorption capacity (qt) was determined by assessing the effect of temperature, pH H2O2, and adsorbent. The results showed that the A-ATP@Fe3O4 achieves the highest removal rate of 99.6% under optimum conditions: 40 °C, pH = 3, H2O2 25 mM, and 0.1 g dosage of the composite. The dye removal procedure achieved adsorption and degradation equilibrium in 120 and 30 min, respectively, by following the same processes as the advanced oxidation approach. Catalytic activity, kinetics, and specified surface characteristics suggest that A-ATP@Fe3O4 is one of the most promising candidates for advanced oxidation-enrooted removal of organic dyes.

Constructing a novel type-Ⅱ ZnO/BiOCOOH heterojunction microspheres for the degradation of tetracycline and bacterial inactivation

A novel ZnO/BiOCOOH microsphere photocatalyst with a type-Ⅱ mechanism was developed for the first time. This strategy was accomplished by immobilizing ZnO onto 3D BiOCOOH microspheres via a single-step hydrothermal synthesis method. The ability to degrade tetracycline (TC) in water under visible light and inactivate bacteria of as-catalyst were analyzed. Among the prepared samples, the ZnO/BiOCOOH composite, with a mass ratio of 40%(Zn/Bi), exhibited the highest photocatalytic activity, which was able to degrade 98.22% of TC in just 90 min and completely eradicated Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in 48 h, and had potential application in solving water resource environmental pollution. The photoelectric characteristics of the photocatalysts were examined by means of electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) spectroscopy. The findings indicated that the superior photocatalytic performance could be credited to the dissociation of electrons (e-) and holes (h+) in heterojunction composites. Finally, electron paramagnetic resonance (EPR) and capture experiments were conducted to confirm the photocatalytic mechanism of the type-Ⅱ heterojunction. This work provides a new Bi-base photocatalyst for aqueous environmental control.

Bismuth oxyformate microspheres assembled by ultrathin nanosheets as an efficient negative material for aqueous alkali battery

A negative electrode with high capacity and rate capability is essential to match the capacity of a positive electrode and maximize the overall charge storage performance of an aqueous alkali battery (AAB). Due to the 3-electron redox reactions within a wide negative potential range, bismuth (Bi)-based compounds are recognized as efficient negative electrode materials. Herein, hierarchically structured bismuth oxyformate (BiOCOOH) assembled by ultrathin nanosheets was prepared by a solvothermal reaction for application as negative material for AAB. Given the efficient ion diffusion channels and sufficient exposure of the inner surface area, as well as the pronounced 3-electron redox activity of Bi species, the BiOCOOH electrode offered a high specific capacity (C_s, 229 ± 4 mAh g^-1 at 1 A g^-1) and superior rate capability (198 ± 6 mAh g^-1 at 10 A g^-1) within 0 ∼ -1 V. When pairing with the Ni₃S₂-MoS₂ battery electrode, the AAB delivered a high energy density (E_cell, 217 mWh cm^-2 at a power density (P_cell) of 661 mW cm^-2), showing the potential of such a novel BiOCOOH negative material in battery-type charge storage.

In situ formation of red/black phosphorus-modified SiO2@g-C3N4 multi-heterojunction for the enhanced photocatalytic degradation of organic contaminants

A new heterojunction material BP/RP-g-C₃N₄/SiO₂ was obtained by a one-step ball milling method, and its photocatalytic capacity was researched by the degradation of Rhodamine B (RhB) and ofloxacin (OFL) in simulated sunlight. The construction of an in situ BP/RP heterojunction can achieve perfect interface contact between different semiconductors and effectively promote the separation of photogenerated carriers. The composite material was well characterized, which proved that the multi-heterogeneous structure was prepared. Furthermore, the type II heterojunction was formed between the g-C₃N₄ and BP/RP interface, playing an important role in the degradation and promoting electron transfer. The degradation effect of BP/RP-g-C₃N₄/SiO₂ on RhB reached 90% after 26 min of simulated solar irradiation, which was 1.8 times that of g-C₃N₄/SiO₂. The degradation of OFL by BP/RP-g-C₃N₄/SiO₂ reached 85.3% after illumination for 50 min, while the degradation of g-C₃N₄/SiO₂ was only 35.4%. The mechanisms were further discussed, and ˙O₂ ^- and h⁺ were found to be the main active substances to degrade RhB. The catalyst also revealed distinguished stability of catalyst and recyclability, and the degradation effect of RhB can still realize 85% after 4 runs of experiment. Thus, this study provided a novel method for the design and preparation of multi-heterojunction catalysts in the removal of organic pollutants from wastewater.

Fabrication of hydrangea-shaped Bi2WO6/ZIF-8 visible-light responsive photocatalysts for degradation of methylene blue

In this paper, the hydrangea-shaped Bi₂WO₆/ZIF-8 (BWOZ) visible light photocatalysts have been prepared via a facile synthetic strategy for the first time. The constructed BWOZ composites were systematically studied by a series of characterization techniques. The SEM results manifested the octahedral ZIF-8 coated the flower-like Bi₂WO₆ uniformly and the composition of BWOZ composites had been confirmed by XPS measurement. And the photocatalytic activity was evaluated by eliminating methylene blue with the help of visible light. The results showed that 7%-BWOZ (7.0 wt% Bi₂WO₆) exhibited better photodegradation capability than pure Bi₂WO₆ and ZIF-8. Compared with Bi₂WO₆, the photocatalytic degradation of methylene blue by 7%-BWOZ could reach 85.7%. In addition, the pseudo-first-order kinetic constant of 7%-BWOZ was 23.00 and 1.61 times that of pristine Bi₂WO₆ and ZIF-8, respectively. The improved photocatalytic ability of BWOZ systems may be due to the construction of heterojunctions between Bi₂WO₆ and ZIF-8, which resulted in the rapid separation of photogenerated carriers. Additionally, the specific surface area of the formed BWOZ system was also improved in comparison with the flower-shaped Bi₂WO₆, and thus more active sites could be provided to contact with methylene blue molecules, thereby achieving better removal capacity. Moreover, trapping experiments and electron spin resonance results further illustrated that the coexistence of multiple free radicals realized efficient degradation of methylene blue. More importantly, the photocatalytic property of the 7%-BWOZ composite remained even after three cycles. Furthermore, a feasible photodegradation mechanism was also explored in depth.