Crystal-structure dependent reaction pathways in photocatalytic formaldehyde mineralization on BiPO4

Synthesis of Heteromorphic Bi2WO6 Films With an Interpenetrate 1D/2D Network Structure for Efficient and Stable Photocatalytic Degradation of VOCs

2D layered Bi2WO6 (BWO) is a widely used attractive photocatalyst for degrading VOCs, but the low visible-light utilization and the easy stacking 2D nanosheets (NSs) limit photocatalysis efficiency and stability. Here, inspired by Eucalyptus, a synergistic strategy of multiscale domain-confinement and electrostatic force action, based on electrospinning is proposed, for fabricating a heteromorphic BWO photocatalyst. It is found that BWO NSs can grow radially in an orderly spaced arrangement along BWO nanofibers (NFs) during sintering, thereby forming 1D/2D BWO junctions like eucalyptus leaves. This interpenetrating 1D/2D network structure not only solves the easy stacking problem of BWO NSs but also selectively exposes the {010} crystal planes that exhibit efficient hole oxidation. In addition, this peculiar structure enriches electrons at the 1D/2D interface to avoid carrier recombination, thus improving the photocatalytic activity. The photocatalyst material with a reduced bandgap width from 2.56 to 2.49 eV can rapidly degrade 100% of acetaldehyde under visible light without using sacrificial agents and photosensitizers and shows superior stability for eight cycles without any decay. This study provides a feasible method to synthesize an efficient and stable BWO photocatalyst.

Efficient degradation of VOCs using semi-coke activated carbon loaded ternary Z-scheme heterojunction photocatalyst BiVO4-BiPO4-g-C3N4 under visible light irradiation

The coal chemical industry generates large amounts of solid waste and volatile organic compounds (VOCs). In this study, the solid waste semi-coke powder obtained in the semi-coke production process was used as a raw material to prepare high-specific surface area semi-coke activated carbon (SAC) by a carbonization and activation process, and a ternary z-scheme heterojunction photocatalyst with high catalytic performance was loaded for synergistic treatment by adsorption and photodegradation to achieve waste treatment with waste. The prepared semi-coke activated carbon has a specific surface area of 619.27 m² g^-1, which can achieve effective adsorption of VOCs. The ternary z-scheme heterojunction photocatalyst BiPO₄-BiVO₄-g-C₃N₄ (PVCN) was supported on a semi-coke activated carbon substrate by a one-step sol-gel method. Based on the synergistic effect of adsorption and photocatalysis, the obtained PVCN/SAC material can degrade toluene by 85.6% within 130 minutes under simulated sunlight irradiation, which is 2.43 times that of pure photocatalyst. The rate of degrading toluene can be increased by 4.43 times. Capture experiments showed that superoxide radicals (_˙O₂^-) and hydroxyl radicals (_˙OH) were the key active species in the degradation pathway. Even after five cycles, the material maintained 81.6% of the degradation performance. In this work, we deeply investigate the mechanism of semi-coke activated carbon as a matrix for enhancing photocatalytic degradation performance. The findings of this work provide new insights into the efficient degradation of VOCs and provide a good theoretical basis for the development of high-performance photocatalysts.

Rno_circRNA_008646 regulates formaldehyde induced lung injury through Rno-miR-224 mediated FOXI1/CFTR axis

Formaldehyde (FA) serves as a prevailing air pollutant, which has seriously threatened public health in recent years. Of all the known health effects, lung injury is one of the most severe risks. However, little is known about the circRNAs related molecular mechanism in the development of lung injury induced by FA. This study was designed to explore the potential roles of dysregulated circRNAs as well as its mechanism in FA-induced lung injury. In the present study, 24 male SD rats were exposed to formaldehyde (control, 0.5, 2.46 and 5 mg/m³) for 8 h per day for 8 weeks to induce lung injury. We used H&E staining to evaluate the histopathological changes of lung injury indifferent groups. The expression of circRNAs in lung tissue was detected by real-time PCR. Meanwhile, circRNA/miRNA/mRNA interaction networks were predicted by bioinformatics analysis. Our study revealed that formaldehyde exposure resulted in abnormal histopathological changes in lung tissues. Moreover, the expression of rno_circRNA_008646 was significantly higher in lung tissues of formaldehyde exposure rats than in control. Bioinformatics analysis showed that one potential target miRNA/mRNA for rno_circRNA_008646 was rno-miR-224/Forkhead Box I1 (FOXI1). Besides, luciferase report gene confirmed that there was targeted binding relationship between rno_circRNA_008646 and rno-miR-224, rno-miR-224 and FOXI1. Further verification experiments indicated that the expression of rno_circRNA_008646 was negatively correlated rno-miR-224, while it was positively correlated with FOXI1. JASPAR database showed transcription factor FOXI1 located in promotor of CF Transmembrane Conductance Regulator (CFTR). Both FOXI1 and CFTR were up-regulated in lung tissues after formaldehyde exposure. In conclusion, our findings suggested that formaldehyde may induce lung injury, and this may be caused by up-regulatedrno_circRNA_008646, which medicated rno-miR-224/FOXI1/CFTR axis.

Degradation of Tetracycline Hydrochloride by a Novel CDs/g-C3N4/BiPO4 under Visible-Light Irradiation: Reactivity and Mechanism

In recent years, with the large-scale use of antibiotics, the pollution of antibiotics in the environment has become increasingly serious and has attracted widespread attention. In this study, a novel CDs/g-C3N4/BiPO4 (CDBPC) composite was successfully synthesized by a hydrothermal method for the removal of the antibiotic tetracycline hydrochloride (TC) in water. The experimental results showed that the synthesized photocatalyst was crystalline rods and cotton balls, accompanied by overlapping layered nanosheet structures, and the specific surface area was as high as 518.50 m2/g. This photocatalyst contains g-C3N4 and bismuth phosphate (BiPO4) phases, as well as abundant surface functional groups such as C=N, C-O, and P-O. When the optimal conditions were pH 4, CDBPC dosage of 1 g/L, and TC concentration of 10 mg/L, the degradation rate of TC reached 75.50%. Active species capture experiments showed that the main active species in this photocatalytic system were holes (h+), hydroxyl radicals, and superoxide anion radicals. The reaction mechanism for the removal of TC by CDBPC was also proposed. The removal of TC was mainly achieved by the synergy between the adsorption of CDBPC and the oxidation of both holes and hydroxyl radicals. In this system, TC was adsorbed on the surface of CDBPC, and then the adsorbed TC was degraded into small molecular products by an attack with holes and hydroxyl radicals and finally mineralized into carbon dioxide and water. This study indicated that this novel photocatalyst CDBPC has a huge potential for antibiotic removal, which provides a new strategy for antibiotic treatment of wastewater.

Surface design of g-C3N4 quantum dot-decorated TiO2(001) to enhance the photodegradation of indoor formaldehyde by experimental and theoretical investigation

Formaldehyde (CHOH), a common volatile organic compound, causes many adverse effects on human health. The highly exposed TiO2(001) facet possesses a high photodegradation efficiency of CHOH due to its excellent ability to trap photogenerated holes and high density of surface unsaturated Ti atoms (Ti5c) to bind CHOH. However, the rapid recombination of photoinduced electron-hole pairs of TiO2(001) limits the photodegradation efficiency. We adopted a strategy of decorating TiO2(001) with g-C3N4 quantum dots (QDs), exploiting the quantum effect of g-C3N4QDs and their combined staggered band structure. This decoration improves the photocatalytic activity of TiO2(001). Moreover, the chemical configuration of g-C3N4QDs/TiO2(001) and the combination mode between the g-C3N4QDs and TiO2(001) support were explored in detail using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. Following the physiochemical characteristic results, the transport mechanism of photoinduced carriers was further analyzed by ultraviolet photoelectron spectroscopy (UPS), electron paramagnetic resonance (EPR), and Heyd-Scuseria-Ernzerh (HSE) exchange-correlation functional calculations. Finally, the performance and reaction mechanism of the photodegradation of CHOH by TiO2(001) and g-C3N4QDs/TiO2(001) were thoroughly investigated. The results show that the g-C3N4QDs were composed of an N-defect tri-s-triazine supported by TiO2(001) via a strong C-O-Ti chemical bond, which accelerated the separation of photoinduced carriers through a Z-scheme route. The photodegradation and mineralization efficiencies of CHOH were significantly promoted by 30% and 60% for g-C3N4QDs/TiO2(001) compared with those of TiO2(001). The photodegradation mechanism proceeded as CHOH - dioxymethylene - formate - carbonate - CO2. This study provides a surface engineering means to design highly active modified TiO2 for CHOH photodegradation.