Search Results (86)

In this study, a novel Bi₂O₃/BiOBr_0.9I_0.1 (BO0.9−BBI0.1) composite photocatalyst was successfully synthesized via a single-pot solvothermal method for the efficient degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under visible light. The structure, morphology, and optical properties of the photocatalyst were characterized through X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS), Steady-state photoluminescence (PL), and Electrochemical Impedance Spectroscopy (EIS). The composite exhibits a 3D hierarchical morphology with increased specific surface area and optimized pore structure, enhancing pollutant adsorption and providing more active sites. Under visible light irradiation, BO0.9−BBI0.1 achieved a 92.4% removal rate of 2,4-D within 2 h, with a reaction rate constant 5.3 and 4.6 times higher than that of pure BiOBr and BiOI, respectively. Mechanism studies confirm that photogenerated holes (h⁺) and superoxide radicals (·O₂⁻) are the primary active species, and the Z-scheme charge transfer pathway significantly promotes the separation of electron-hole pairs while maintaining strong redox capacity. The catalyst also demonstrated good stability over multiple cycles. This work provides a feasible dual-modification strategy for designing efficient bismuth-based photocatalysts for pesticide wastewater treatment. Full article

CuO/TiO₂ is a highly active visible-light-driven photocatalyst. The precise structural regulation of TiO₂ and the quantum dot-scale loading strategy of CuO have long been researching hotspots and challenges. This work presents an ingenious synthetic strategy, leveraging the photoinduced superhydrophilicity and dark-induced reversible hydrophobicity of TiO₂, coupled with carbon quantum dots (CQDs) as “seeds” to induce the in situ synthesis of CuO quantum dots (CuO QDs). Specifically, CuO QDs with an average diameter of 5–10 nm were successfully anchored onto TiO₂ nanowire arrays (TNWAs) with a diameter of 10–15 nm. By adjusting the dosage of “seeds” (CQDs), the loading amount of CuO QDs can be effectively controlled. Corresponding characterizations were performed, including ultraviolet-visible-near-infrared (UV-Vis-NIR spectroscopy) for optical absorption properties, photoluminescence (PL) spectroscopy for photoluminescent behavior, electron paramagnetic resonance (EPR) spectroscopy for free radical generation capability, and bisphenol A (BPA) degradation assays for photocatalytic performance. Loading 4.78 wt% CuO QDs can effectively inhibit the recombination of electron–hole pairs in TNWAs. Simultaneously, it prolongs the lifetime of charge carriers (photoelectrons) and enhances the yields of hydroxyl radicals (•OH) and superoxide radicals (•O₂⁻). The BPA degradation efficiency of the CuO QDs/TNWA composite is 2.4 times higher than that of TNWAs. Furthermore, we found that the loading of CuO QDs significantly modulates the depletion layer width of the P–N heterojunction, and the underlying mechanism has been discussed in detail. Full article

The growing body of biomedical research reveals that many biological processes are governed by quantum physical principles, including the effects of weak magnetic fields (MFs) at or below geomagnetic strength. Given that life evolved within the geomagnetic field, its significant decrease—the hypomagnetic field (hypoMF)—may disrupt fundamental biological processes. This is particularly relevant for interplanetary missions, where astronauts will encounter prolonged hypoMF conditions alongside other spaceflight stressors. This mini-review synthesizes current knowledge on hypoMF effects, comparing terrestrial and extraterrestrial MF conditions and evaluating evidence from human studies. The initial database search identified 645 records. After most were excluded for various reasons, only 44 publications on the effects of MFs on the entire human body were included in the review. An effect of the hypoMF was reported in 10 of these studies and was absent in 4. Despite some methodological limitations in the available research, the evidence suggests that the human body is not indifferent to hypoMF exposure. We also discuss leading mechanistic molecular hypotheses—particularly the radical pair mechanism. Finally, we identify urgent research priorities to elucidate hypoMF’s biological role and develop countermeasures for future deep space exploration. Addressing these gaps is essential for safeguarding astronaut health and advancing magnetobiology as a frontier discipline in biophysics. Full article

The Earth’s geomagnetic field (GMF) is a fundamental environmental signal for plants, with its perception rooted in quantum biology. Specifically, the radical pair mechanism (RPM) explains how this weak force influences electron spin states in metabolic pathways, providing a framework for its profound biological impact. Research shows that a hypomagnetic field (hMF) directly reduces the production of reactive oxygen species (ROS), creating a quantum signature in plants. This is a counterintuitive finding, as it suggests the plant perceives less oxidative stress and, in response, downregulates its antioxidant defenses. This multi-level effect, from a quantum trigger to molecular and metabolic changes, ultimately affects the plant’s growth and phenotype. This review suggests a possible link between the GMF and plant health, identifying the GMF as a potential physiological modulator. Manipulating the magnetic field could therefore be a novel strategy for improving crop resilience and growth. However, the fact that some effects cannot be fully explained by the RPM suggests other quantum mechanisms are involved, paving the way for future research into these undiscovered processes and their potential inheritance across generations. Full article

This research successfully synthesized a novel n-n heterojunction Bi₂O₂CO₃/AgVO₃ nanocomposite photocatalyst via the in situ chemical deposition process. Characterization results strongly confirmed the formation of a tight heterojunction at the Bi₂O₂CO₃/AgVO₃ interface. The nanocomposite exhibited characteristic XRD peaks and FT-IR vibrational modes of both Bi₂O₂CO₃ and AgVO₃ simultaneously. Electron microscopy images revealed AgVO₃ nanorods tightly and uniformly loaded onto the surface of Bi₂O₂CO₃ nanosheets. Compared to the single-component Bi₂O₂CO₃, the composite photocatalyst exhibited a red shift in its optical absorption edge to the visible region (515 nm) and a decrease in bandgap energy to 2.382 eV. Photoluminescence (PL) spectra demonstrated the lowest fluorescence intensity for the nanocomposite, indicating that the recombination of photogenerated electron–hole pairs was suppressed. After 90 min of visible-light irradiation, the degradation efficiency of Bi₂O₂CO₃/AgVO₃ toward methylene blue (MB) reached up to 99.55%, with photodegradation rates 2.51 and 2.79 times higher than those of Bi₂O₂CO₃ and AgVO₃, respectively. Furthermore, the nanocomposite exhibited excellent cycling stability and reusability. MB degradation was gradually enhanced with increasing the photocatalyst dosage and decreasing initial MB concentration. Radical trapping experiments and absorption spectroscopy of the MB solution revealed that reactive species h⁺ and ·O₂⁻ could destroy and decompose the chromophore groups of MB molecules effectively. The possible mechanism for enhancing photocatalytic performance was suggested, elucidating the crucial roles of charge carrier transfer and active species generation. Full article

The reactions of 7 radicals, which play a key role in the degradation of water contaminants in Advanced Oxidation Processes, were discussed and compared. For evaluation of the reactivities and comparisons, the chemical reactivity rate constants were used, i.e., the rate constant that would be measured if diffusion of the species was not rate-influencing (k_chem). By selecting appropriate diffusion-controlled rate constants (k_diff) and using the measured rate constant (k) values, k_chem was calculated by the Noyes equation: 1/k = 1/k_chem + 1/k_diff. When k and k_diff were close to each other, k_chem was much higher than k. log k_chem values showed good correlation in the cases of the ^•OH-H^•, SO₄^•−-^•OH, and Cl₂^•−-CO₃^•− radical pairs, moderate correlation was found in the case of the CO₃^•−-ClO^• pair. The correlations may reflect, at least partly, similar reaction mechanisms, and allow estimation of unknown rate constant values. No correlation was found for the ^•OH-Cl^• pair; this indicates highly different reaction mechanisms. The reactivity of oxidizing radicals decreases with decreasing reduction potential in the order: Cl^• > ^•OH > SO₄^•− > Cl₂^•− > CO₃^•− > ClO^•. The reductive H^• reactions with organic molecules are similar to those of ^•OH, although the H^• rate constants are 0.5–1 order of magnitude smaller. Full article

Utilizing isomeric monomers to construct covalent organic frameworks (COFs) could easily and precisely regulate their structure in order to raise the photocatalytic performance towards two-step single-electron oxygen reduction reaction (ORR) to hydrogen peroxide (H₂O₂). Herein, isomeric anthraquinone (AQ)-based COFs (designated as 1,4-DQTP and 2,6-DQTP) were successfully fabricated through a simple yet effective one-step solvothermal synthesis approach, only utilizing isomeric monomers with alterations in the catalysts. Specifically, the black 1,4-DQTP displayed a high photocatalytic H₂O₂ production rate of 865.4 µmol g⁻¹ h⁻¹, with 2.44-fold enhancement compared to 2,6-DQTP (354.7 µmol g⁻¹ h⁻¹). Through a series of experiments such as electron paramagnetic resonance (EPR) spectroscopy and the free radical quenching experiments, as well as density functional theory (DFT) calculations, the photocatalytic mechanism revealed that compared with 2,6-DQTP, 1,4-DQTP possessed a stronger and broader visible light absorption capacity, and thus generated more photogenerated e⁻-h⁺ pairs. Ultimately, more photogenerated electrons were enriched on the AQ motif via a more apparent electron push–pull effect, which provided a stable transfer channel for e⁻ and thus facilitated the generation of superoxide anion radical intermediates (•O₂⁻). On the other hand, the negative charge region of AQ’s carbonyl group evidently overlapped with that of TP, indicating that 1,4-DQTP had a higher chemical affinity for the uptake of protons, and thus afforded a more favorable hydrogen donation for H⁺. As a consequence, the rational design of COFs utilizing isomeric monomers could synergistically raise the proton-coupled electron transfer (PCET) kinetics for two-step single-electron ORR to H₂O₂ under visible light illumination. This work provides some insights for the design and fabrication of COFs through rational isomer engineering to modulate their photocatalytic activities. Full article

To address the challenge of abatement of volatile organic compounds (VOCs) in environmental catalysis, this study developed a temperature-gradient hydrothermal strategy to fabricate SrSn(OH)₆ nanocatalysts and systematically investigatd their photocatalytic performance and mechanisms for gaseous toluene degradation. SrSn(OH)₆ (SSH) was synthesized via a simple hydrothermal method with optimal preparation conditions identified as a reaction temperature of 140 °C and duration of 12 h. The crystallinity of SrSn(OH)₆ was modulated by adjusting the pH of the precursor solution, yielding materials with distinct morphologies, specific surface areas, and band gaps. The narrowed band gap of SrSn(OH)₆ nanocatalysts facilitated electron excitation to generate additional photogenerated electron-hole pairs. The SSH-10.5 sample with ordered planar and hole-like structures promoted carrier migration, effectively suppressed electron-hole recombination, and enhanced the conversion of abundant surface hydroxyl groups into hydroxyl radicals. Under UV irradiation, SSH-10.5 achieved a toluene degradation efficiency of 69.56% and showed excellent stability after five reuse cycles. Electron spin resonance analysis confirmed the presence of •OH and •O₂⁻ radicals in the reaction system, with •OH identified as the dominant active species. In situ FT-IR spectroscopy revealed that •OH and •O₂⁻ radicals attacked the methyl group of toluene, converting it into intermediates including benzyl alcohol, benzaldehyde, and benzoic acid. This work provides a novel design of high-efficiency VOC-photocatalytic materials and shows significant implications for advancing industrial exhaust gas purification technologies. Full article

In this study, a contact–separation triboelectric catalytic device was designed and constructed to systematically investigate the underlying degradation mechanism. The device enabled precise control of the contact–separation process between frictional surfaces. Polytetrafluoroethylene (PTFE) and polyethylene terephthalate (PET) films were selected as the triboelectric pair, and methylene blue (MB) was used as the model organic pollutant. Experimental results demonstrated that the contact–separation process in an aqueous environment effectively promotes the degradation of organic dyes. For an MB solution with an initial concentration of 5 mg/L, a degradation efficiency of 40.34% was achieved within 3 h. Moreover, the device exhibited excellent repeatability and stability, with no significant decline in performance after 15 h of continuous operation. Control experiments confirmed that the degradation originates specifically from the contact–separation interaction between the PTFE and PET surfaces. Free radical quenching experiments identified superoxide radicals (·O₂⁻) and hydroxyl radicals (·OH) as the primary reactive species responsible for degradation. Based on these findings, a microscopic mechanism is proposed: during contact, triboelectric charging generates electrons (e⁻) and holes (h⁺) on the surfaces; upon separation, these charges interact with the solution—e⁻ reduce dissolved oxygen to form ·O₂⁻, while h⁺ oxidize hydroxide ions (OH⁻) to produce ·OH. The combined action of ·O₂⁻ and ·OH ultimately results in the efficient degradation of MB. Full article

Catalysts with anionic metal centers have recently been proposed to enhance the performance of various chemical processes. Here, we focus on the reactivity of ${\mathrm{Co}\left(\mathrm{CO}\right)}_4^{-}$ for the polymerization of aziridine and carbon monoxide to form polypeptoids, motivated by earlier experimental studies. We used multi-reference and density functional theory methods to investigate possible reaction mechanisms and provide insights into the role of the negatively charged cobalt center. Two different reaction paths were identified. In the first path, ${\mathrm{Co}}^{-}$ acts as a nucleophile, donating an electron pair to the reaction substrate, while in the second path, it performs a single electron transfer to the substrate, initiating radical polymerization. The difference in the activation barriers for the two key steps is small and falls within the accuracy of our calculations. As suggested in the literature, solvent effects can play a primary role in determining the outcomes of such reactions. Future investigations will involve different metals or ligands and will investigate the effects of these two reaction paths on other chemical transformations. Full article

Semiconductor photocatalytic technology demonstrates strong potential as a solution to defend environmental systems while converting energy. The photocatalytic behavior of traditional ZrO₂ catalysts suffers a major disadvantage because their activity remains low in visible light applications. XRD together with SEM, as well as EDX and EIS techniques, were utilized to evaluate the synthetic materials. This study demonstrated that the development of RGO-modified ZrO₂ heterostructures delivered substantial increases in photocatalytic functionality through effective photogenerated charge separation mechanisms. Tests showed the RGO/ZrO₂ heterostructures exhibited outstanding photocatalytic behavior that led to an 80% MB solution breakdown in 120 min while exceeding electrocatalytic parameters in multiple tests. The experimental data from UV–vis spectroscopy combined with electrochemical analysis and radical trapping methods demonstrated that heterostructure improvement resulted from higher light absorption rates and effective active site exposure while providing better electron/hole pair separation. This research establishes S-scheme heterostructures to enable advancements in environmental protection alongside energy conversion technologies. Full article

The cryptochromes are flavoproteins that either individually or synergistically respond to light and magnetic field directionality as well as are implicated in circadian rhythm entrainment and development. Single brief exposures (10 min) to low energy (1.5 mT) pulsed electromagnetic fields (PEMFs) were previously shown to enhance myogenesis by stimulating transient receptor potential canonical 1 (TRPC1)-mediated Ca²⁺ entry, whereby downwardly directed fields produced greater myogenic enhancement than upwardly directed fields. Here, we show that growth in the dark results in myoblasts losing their sensitivity to both magnetic field exposure and directionality. By contrast, overexpressing or silencing cryptochrome circadian regulator 2 (CRY2) in myoblasts enhances or reduces PEMF responses, respectively, under conditions of ambient light. Reducing cellular flavin adenine dinucleotide (FAD) content by silencing riboflavin kinase (RFK) attenuated responsiveness to PEMFs and inhibited selectivity for magnetic field direction. The upregulation of TRPC1 and cell cycle regulatory proteins typically observed in response to PEMF exposure was instead attenuated by upwardly directed magnetic fields, growth in the darkness, magnetic shielding, or the silencing of CRY2 or RFK. A physical interaction between CRY2 and TRPC1 was detected using coimmunoprecipitation and immunofluorescence, revealing their co-translocation into the nucleus after PEMF exposure. These results implicate CRY2 in an identified TRPC1-dependent magnetotransduction myogenic cascade. Full article

In this review, we focus on the one-electron oxidation of DNA, which is a multipart event controlled by several competing factors. We will discuss the oxidation free energies of the four nucleobases and the electron detachment from DNA, influenced by specific interactions like hydrogen bonding and stacking interactions with neighboring sites in the double strand. The formation of a radical cation (hole) which can migrate through DNA (hole transport), depending on the sequence-specific effects and the allocation of the final oxidative damage, is also addressed. Particular attention is given to the one-electron oxidation of ds-ODN containing G:C pairs, including the complex mechanism of the deprotonation vs. hydration steps of a G:C^•+ pair, as well as to the modes of formation of the two guanyl radical tautomers after deprotonation. Among the reactive oxygen species (ROS) generated in aerobic organisms by cellular metabolisms, several oxidants react with DNA. The mechanism of stable product formation and their use as biomarkers of guanine oxidation in DNA damage are also addressed. Full article

This study explores the complex relationship between radio frequency (RF) exposure and cancer cells, focusing on the HT-1080 human fibrosarcoma cell line. We investigated the modulation of reactive oxygen species (ROS) and key antioxidant enzymes, including superoxide dismutase (SOD), peroxidase, and glutathione (GSH), as well as mitochondrial superoxide levels and cell viability. Exposure to RF fields in the 2–5 MHz range at very weak intensities (20 nT) over 4 days resulted in distinct, frequency-specific cellular effects. Significant increases in SOD and GSH levels were observed at 4 and 4.5 MHz, accompanied by reduced mitochondrial superoxide levels and enhanced cell viability, suggesting improved mitochondrial function. In contrast, lower frequencies like 2.5 MHz induced oxidative stress, evidenced by GSH depletion and increased mitochondrial superoxide levels. The findings demonstrate that cancer cells exhibit frequency-specific sensitivity to RF fields even at intensities significantly below current safety standards, highlighting the need to reassess exposure limits. Additionally, our analysis of the radical pair mechanism (RPM) offers deeper insight into RF-induced cellular responses. The modulation of ROS and antioxidant enzyme activities is significant for cancer treatment and has broader implications for age-related diseases, where oxidative stress is a central factor in cellular degeneration. The findings propose that RF fields may serve as a therapeutic tool to selectively modulate oxidative stress and mitochondrial function in cancer cells, with antioxidants playing a key role in mitigating potential adverse effects. Full article

While the photophysics of closed-shell organic molecules is well established, much less is known about open-shell systems containing interacting radical pairs. In this work, we investigate the ultrafast excited state dynamics of a singlet verdazyl diradical system in solution using transient absorption (TA) spectroscopy for the first time. Following 510 nm excitation of the excitonic S₀ → S₁ transition, we detected TA signals in the 530–950 nm region from the S₁ population that decayed exponentially within a few picoseconds to form a vibrationally hot S₀* population via internal conversion. The dependence of the S₁ decay rate on solvent and radical–radical distance revealed that the excited state possesses charge-transfer character and likely accesses the S₀ state via torsional motion. The ultrafast internal conversion decay mechanism at play in our open-shell verdazyl diradicals is in stark contrast with other closed-shell, carbonyl-containing organic chromophores, which exhibit ultrafast intersystem crossing to produce long-lived triplet states as the major S₁ decay pathway. Full article