Peroxide Generation Research Articles

Ultrasound-assisted bisphenol AF degradation using in situ generated hydrogen peroxide

Bisphenol AF (BPAF) is degraded through the ultrasound-assisted in situ generation and activation of hydrogen peroxide (H2O2) by the copper(II) catalysed oxidation of hydroxylamine (NH2OH) with dioxygen (O2). Compared to added H2O2, in situ generated H2O2 significantly improves the degradation of BPAF from 46.7% to 94.8% in ∼15 min. The reaction follows a pseudo-first-order kinetic model. This study examines the influence of solution pH, anions, humic acid, and different concentrations of the reactants on BPAF degradation. Mass spectrometry was used to identify the BPAF degradation products, and a degradation pathway is proposed. This work advances the understanding of in situ hydrogen peroxide generation and activation in advanced oxidation (Fenton-like) processes (AOPs).

Ferritin with methylglyoxal produces reactive oxygen species but remains functional

Iron is necessary for life, but the simultaneous iron-catalyzed formation of reactive oxygen species (ROS) is involved in pathogenesis of many diseases. One of them is diabetes mellitus, a widespread disease with severe long-term complications, including neuropathy, retinopathy, and nephropathy. Much evidence points to methylglyoxal, a potent glycating agent, as the key mediator of diabetic complications. In diabetes, there is also a peculiar dysregulation of iron homeostasis, leading to an expansion of redox-active iron. This in vitro study focuses on the interaction of methylglyoxal with ferritin, which is the main cellular protein for iron storage. Methylglyoxal effectively liberates iron from horse spleen ferritin, as well as synthetic iron cores; in both cases, it is partially mediated by superoxide. The interaction of methylglyoxal with ferritin increases the production of hydrogen peroxide, much above the generation of peroxide by methylglyoxal alone, in an iron-dependent manner. Glycation with methylglyoxal results in structural changes in ferritin. All of these findings can be demonstrated with pathophysiologically relevant (submillimolar) methylglyoxal concentrations. However, the rate of iron release by ascorbate, the ferroxidase activity, or the diameter of gated pores even in intensely glycated ferritin is not altered. In conclusion, although the functional features of ferritin resist alterations due to glycation, the interaction of methylglyoxal with ferritin liberates iron and markedly increases ROS production, both of which could enhance oxidative stress in vivo. Our findings may have implications for the pathogenesis of long-term diabetic complications, as well as for the use of ferritin as a nanocarrier in chemotherapy.

Fluorine-Doped Graphene Oxide-Modified Graphite Felt Cathode for Hydrogen Peroxide Generation

Electrochemical oxygen reduction via the two-electron pathway (2e-ORR) is an emerging method for producing H2O2. It is cleaner, safer, and more convenient compared to the anthraquinone process. Graphite felt is one of the cathode candidates for large-scale cells due to its excellent mechanical properties. However, commercial graphite felt often fails to achieve the desired hydrogen-peroxide yield because of its low catalytic selectivity for the 2e-ORR pathway. Fluorine-doped carbon materials are expected to enhance 2e-ORR selectivity. This is because the electronic structure of carbon atoms adjacent to fluorine atoms may facilitate the production of hydrogen peroxide while hindering its further reduction. In this study, fluorine-doped graphene oxide (FGO) was prepared by the hydrothermal method. Subsequently, graphite felt modified with FGO was fabricated and used as the cathode for H2O2 production. The results indicated that in alkaline media, the graphite felt modified with FGO achieved a catalytic selectivity of 93% and a generation rate of 8.91 mg cm⁻2 h⁻¹. In comparison, commercial graphite felt had a catalytic selectivity of 75% and a generation rate of 2.10 mg cm⁻2 h⁻¹. Moreover, graphite felt modified by FGO also exhibited excellent electrocatalytic performance for H2O2 generation in neutral media. This research provides a fundamental study to promote the application of graphite felt in the environmentally friendly electrocatalytic production of hydrogen peroxide in industries.

Bi2Te3/Carbon Nanotube Hybrid Nanomaterials as Catalysts for Thermoelectric Hydrogen Peroxide Generation

Harnessing waste heat from environmental or industrial sources presents a promising approach to eco-friendly and sustainable chemical synthesis. In this study, we introduce a thermoelectrocatalytic (TECatal) system capable of utilizing even small amounts of heat for hydrogen peroxide (H2O2) production. We developed a nanohybrid structure, combining carbon nanotubes (CNTs) and Bi2Te3 nanoflakes (Bi2Te3/CNTs), through a one-pot synthesis method. Bi2Te3, as a thermoelectric (TE) material, generates charge carriers under a temperature gradient via the Seebeck effect, enabling them to participate in surface redox reactions. However, the rapid recombination of these charge carriers greatly limits the TECatal activity. In the Bi2Te3/CNTs nanohybrid system, the introduction of CNTs substantially enhances the efficiency of H2O2 production, as the strong bonding between CNTs and Bi2Te3, along with the excellent conductivity of CNTs, facilitates charge carrier separation and transport, as confirmed by TE electrochemical tests. This study underscores the significant potential of thermoelectric nanomaterials for converting waste heat into green chemical synthesis.

Visible light-driven aerobic oxidation of amines coupling with H2O2 production catalyzed by CoPc/alkali metal-doped g-C3N4 Z-scheme heterojunction

Three environmentally friendly Z-scheme CoPc/alkali metal-doped g-C3N4 heterojunction composites were fabricated via in-situ immobilizing cobalt phthalocyanine (CoPc) on the surface of alkali metal-doped g-C3N4 nanosheet by simple hydrothermal method. These composites acted as efficient and recyclable heterogeneous photocatalysts realized that the highly selective aerobic oxidation of amines to the corresponding imines coupling of hydrogen peroxide generation at room temperature. Under irradiation by LED lamp, the imines and H2O2 were obtained with conversion ranges from 87.9 % to 92.0 %, selectivity more than 99 %, and production rate ranges from 3.27 to 3.40 mmol g−1 h−1, respectively. Based on the mechanistic analysis and characterization, the excellent catalytic activity derived from the Z-scheme mechanic and synergistic effect originated from O2 reduction and amine oxidation. On completion, after centrifugation, washing with solvent and drying under vacuum, the catalysts can be recovered and reused for five successive cycles of testing with a slight decrease in reactivity. For this work, a promising photo synthesis pathway with merits of mild, low-cost, pollution-free, and energy-saving was developed to produce imines coupling with H2O2 generation.

A self-sufficient catalytic nanofiber evaporator for solar-driven efficient water purification through in-situ hydrogen peroxide generation

Solar-driven interfacial water evaporation (SDIWE) is an emerging technology for the production of clean water driven by inexhaustible energy source, but its application suffers from volatile organic compounds (VOCs) escaping into condensate water. Herein, a bifunctional SDIWE system integrated with Fenton process was proposed to achieve self-sufficient (not adding any additional chemicals to feed water) high-quality freshwater production from VOCs-contained wastewater through in-situ hydrogen peroxide (H2O2) generation. The hybrid SDIWE system based on AgNPs (Ag nanoparticles)@graphitic carbon nitride (g-C3N4)/beta-iron hydroxide oxide (β-FeOOH)-Polyacrylonitrile (AgG/Fe-PAN) nanofiber membrane exhibited an excellent evaporation performance (1.61 kg m-2h−1) under one sun (1 kW m−2). Significantly, in the absence of external oxidant source, the phenol removal rate in condensate water reached 98.4 ± 0.2 % due to the synergic photocatalysis technology and Fenton reaction, which was 6.1 times that of sole SDIWE (16.2 ± 0.5 %). Mechanism analysis reveals that H2O2 was effectively in-situ generated by AgNPs@g-C3N4 particles (∼18.8 μM at 4 h). Subsequently, the produced H2O2 was further activated to •OH radicals via β-FeOOH that ensures the VOCs decomposition during rapid steam generation. Meanwhile, the hybrid system not only exhibited an excellent phenol removal rate of 91.6 ± 0.6 % in wide pH ranges (1–11), but also ensured a good removal performance for various organic pollutants and excellent antibacterial properties. To sum up, the hybrid system has successfully integrated SDIWE technology with various advanced oxidation processes (AOPs), providing a novel way for the pollution-free production of high-quality clean water during the SDIWE process for water purification.

Hypoxia-Induced Mitochondrial ROS and Function in Pulmonary Arterial Endothelial Cells.

Pulmonary artery endothelial cells (PAECs) are a major contributor to hypoxic pulmonary hypertension (PH) due to the possible roles of reactive oxygen species (ROS). However, the molecular mechanisms and functional roles of ROS in PAECs are not well established. In this study, we first used Amplex UltraRed reagent to assess hydrogen peroxide (H2O2) generation. The result indicated that hypoxic exposure resulted in a significant increase in Amplex UltraRed-derived fluorescence (i.e., H2O2 production) in human PAECs. To complement this result, we employed lucigenin as a probe to detect superoxide (O2-) production. Our assays showed that hypoxia largely increased O2- production. Hypoxia also enhanced H2O2 production in the mitochondria from PAECs. Using the genetically encoded H2O2 sensor HyPer, we further revealed the hypoxic ROS production in PAECs, which was fully blocked by the mitochondrial inhibitor rotenone or myxothiazol. Interestingly, hypoxia caused an increase in the migration of PAECs, determined by scratch wound assay. In contrast, nicotine, a major cigarette or e-cigarette component, had no effect. Moreover, hypoxia and nicotine co-exposure further increased migration. Transfection of lentiviral shRNAs specific for the mitochondrial Rieske iron-sulfur protein (RISP), which knocked down its expression and associated ROS generation, inhibited the hypoxic migration of PAECs. Hypoxia largely increased the proliferation of PAECs, determined using Ki67 staining and direct cell number accounting. Similarly, nicotine caused a large increase in proliferation. Moreover, hypoxia/nicotine co-exposure elicited a further increase in cell proliferation. RISP knockdown inhibited the proliferation of PAECs following hypoxia, nicotine exposure, and hypoxia/nicotine co-exposure. Taken together, our data demonstrate that hypoxia increases RISP-mediated mitochondrial ROS production, migration, and proliferation in human PAECs; nicotine has no effect on migration, increases proliferation, and promotes hypoxic proliferation; the effects of nicotine are largely mediated by RISP-dependent mitochondrial ROS signaling. Conceivably, PAECs may contribute to PH via the RISP-mediated mitochondrial ROS.

A multifunctional cascade gas-nanoreactor with MnO2 as a gatekeeper to enhance starvation therapy and provoke antitumor immune response

Glucose oxidase (GOx)-mediated starvation therapy is an effective tumor treatment that blocks energy and activates the immune response. However, the insufficient tumor immunogenicity and immunosuppressive tumor microenvironment (TME) limited its therapeutic efficacy. To address this, we have designed a multifunctional cascade gas-nanoreactor with a MnO2 coating, which serves as an out gatekeeper to encapsulate both GOx and a carbon monoxide (CO) donor (denoted as GCM). Due to the protective effect of MnO2 coating, GCM maintains better stability in normal physiological environments, enhancing the catalytic activity of GOx and minimizing toxic side effects. Upon accumulation in the tumor, the degradation of MnO2 coating exposes the GOx enzyme, thereby initiating a cascade catalysis reaction to generate hydrogen peroxide (H2O2) and release CO in the hypoxic conditions. Additionally, the released Mn2+ reacts with H2O2 to generate toxic hydroxyl radical (•OH) as chemodynamic therapy (CDT). The synergistic treatments of starvation therapy, CO gas therapy and CDT effectively kill cancer cells and amplify immunogenic cell death (ICD), maturing DC cells and activating anti-tumor immune response. Furthermore, the released CO increases M1 macrophages infiltration and reduces myeloid-derived suppressor cells (MDSCs) infiltration, thus reversing the immunosuppressive TME. This multifunctional gas-nanoreactor provides a strategy for CO gas generation to trigger a robust anti-tumor immune response and has the potential for clinical application in cancer immunotherapy. Statement of significanceA multifunctional cascade gas-nanoreactor with a MnO2 gatekeeper was developed to perform synergistic treatments involving starvation therapy, CO gas therapy and chemodynamic therapy (CDT) for tumor elimination. The MnO2 gatekeeper enhanced the catalytic activity of GOx within the nanoreactor by generating oxygen, thereby minimizing toxic side effects after intravenous injection. The gas-nanoreactor amplified ICD through synergistic treatments to mature DC cells and activate anti-tumor immune response. Furthermore, the released CO could reverse the immunosuppression of the TME to enhance cancer immunotherapy. The combination strategy utilizing the gas-nanoreactor demonstrates clinical potential for facilitating cancer immunotherapy.

Nanozymes as Glucose Scavengers and Oxygenerators for Enhancing Tumor Radiotherapy.

Insufficient accumulation of reactive oxygen species (ROS) due to tumor hypoxia significantly contributes to increased radiation resistance and the failure of radiotherapy (RT). Therefore, developing methods to alleviate hypoxia and boost ROS levels represents a promising strategy for enhanced radiosensitivity. This study introduced a self-cascade catalytic Pt@Au nanozymes as a radiosensitizer, using glucose oxidase (GOx)-, catalase (CAT)-, and peroxidase (POD)-like activities to improve hypoxia and increase ROS accumulation, thereby affecting glucose metabolism and enhancing the effects of RT. Pt@Au nanozymes exhibit GOx-like activity, which not only depletes glucose to induce starvation therapy, but also generates hydrogen peroxide (H2O2) for cascade reactions. Moreover, Pt@Au nanozymes demonstrate CAT-like activity, catalyzing the conversion of H2O2 to O2. This conversion effectively alleviates hypoxia, stabilizes ROS, increases DNA damage, significantly enhancing RT efficacy and sustaining the effects of starvation therapy. As high-Z materials, Pt@Au nanozymes can deposit more X-ray energy. Furthermore, the POD-like activity catalyzes the conversion of H2O2 into highly reactive hydroxyl radicals (·OH), which increases ROS levels and enhances RT. Pt@Au nanozymes serve as X-ray computed tomography (CT) imaging agents, allowing for clear differentiation between tumor and normal tissue boundaries and enhancing the precision of RT. In summary, Pt@Au nanozymes serve as effective radiosensitizers by depleting glucose to induce starvation therapy, enhancing cascade reactions, and inhibiting tumor proliferation. Through their self-cascade reactions, these nanozymes dramatically increase oxygen levels within tumors, reduce hypoxia, and enhance ROS levels. This advancement addresses the radioresistance associated with hypoxic tumors, paving the way for innovative strategies in RT.

UiO-66(Zr)-2OH-Supported Pd0 NP Catalysts Accelerated a Fenton-Like Reaction: Iron Cycling and Hydrogen Peroxide Generation Achieved Simultaneously.

Both the sluggish kinetics of Fe(II) regeneration and usage restriction of H2O2 have severely hindered the scientific progress of the Fenton reaction toward practical applications. Herein, a reduction strategy of activated hydrogen, which was used to simultaneously generate H2O2 and accelerate the regeneration of ferrous in a Fenton-like reaction based on the reduction of activated hydrogen derived from H2, was proposed. Two types of composite catalysts, namely, Pd/UiO-66(Zr)-2OH and Pd@UiO-66(Zr)-2OH, were successfully prepared by loading nano-Pd particles onto the outer and inner pores of UiO-66(Zr)-2OH in different loading modes, respectively. They were used to enhance the reduction of activated hydrogen. The characterization results based on the analysis of scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy revealed that the materials were successfully prepared. By using a trace amount of ferrous iron and without adding H2O2, trimethoprim (C0 = 20 mg·L-1), as a target pollutant, could be nearly 100% degraded within 180 min in the reaction system composed of these two materials. The cycle of iron and the self-generation of H2O2 were verified by the detection of ferrous H2O2 in the system. Density functional theory calculation results further confirmed that the pore-filled Pd0 NPs, as the main catalytic site for Pd@UiO-66(Zr)-2OH, could produce H2O2 under the combined action of hydrogen and oxygen. The Pd@UiO-66(Zr)-2OH system had excellent stability after multiple applications (at least 6 cycles), all of which resulted in 100% removal of trimethoprim. The degradation efficiency of the Pd/UiO-66(Zr)-2OH system for TMP gradually decreased from 97 to 80% after six cycles. The results of electron paramagnetic resonance combined with classical radical burst experiments revealed the degradation pathways in the reaction system with hydroxyl radicals and singlet oxygen as the main reactive oxygen particles.

Assessing the therapeutic potential of KK14 peptide derived from Cyprinus Carpio in reducing intercellular ROS levels in oxidative Stress-Induced In vivo zebrafish larvae model: An integrated bioinformatics, antioxidant, and neuroprotective analysis.

H2O2 is a significant reactive oxygen species (ROS) that hinders redox-mediated processes and contributes to oxidative stress and neurodegenerative disorders. Oxidative stress causes impairment of cell macromolecules, which results in cell dysfunction and neurodegeneration. Alzheimer's disease and other neurodegenerative diseases are serious conditions linked to oxidative stress. Antioxidant treatment approaches are a novel and successful strategy for decreasing neurodegeneration and reducing oxidative stress. This study explored the antioxidant and neuroprotective characteristics of KK14 peptide synthesized from LEAP 2B (liver-expressed antimicrobial peptide-2B) derived from Cyprinus carpio L. Molecular docking studies were used to assess the antioxidant properties of KK14. The peptide at concentrations 5-45 μM was examined by using in vitro and in vivo assessment. Analysis was done on the developmental and neuroprotective potential of KK14 peptide treatment in H2O2-exposed zebrafish larvae which showed Nonlethal deformities. KK14 improves antioxidant enzyme activity like catalase and superoxide dismutase. Furthermore, it reduces neuronal damage by lowering lipid peroxidation and nitric oxide generation while increasing acetylcholinesterase activity. It improved the changes in swimming behavior and the cognitive damage produced by exposure to H2O2. To further substantiate the neuroprotective potential of KK14, intracellular ROS levels in zebrafish larvae were assessed. This led to a reduction in ROS levels and diminished lipid peroxidation. The KK14 has upregulated the antioxidant genes against oxidative stress. Overall, this study proved the strong antioxidant activity of KK14, suggesting its potential as a strong therapeutic option for neurological disorders caused by oxidative stress.

Two-Dimensional Covalent Organic Frameworks with Carbazole-Embedded Frameworks Facilitate Photocatalytic and Electrocatalytic Processes

Catalytic technologies are pivotal in enhancing energy efficiency, promoting clean energy production, and reducing energy consumption in the chemical industry. The pursuit of novel catalysts for renewable energy is a long-term goal for researchers. In this work, we synthesized three two-dimensional covalent organic frameworks (COFs) featuring electron-rich carbazole-based architectures and evaluated their catalytic performance in photocatalytic organic reactions and electrocatalytic oxygen reduction reactions (ORRs). Pyrene-functionalized COF, termed as FCTD-TAPy, demonstrated excellent photocatalytic performance for amino oxidation coupling and showed a remarkable preference for substrates with electron-withdrawing groups (up to >99% Conv. and >99% Sel). Furthermore, FCTD-TAPy favored a four-electron transfer pathway during the ORR and exhibited favorable reaction kinetics (51.07 mV/dec) and a high turnover frequency (0.011 s−1). In contrast, the ORR of benzothiadiazole-based FCTD-TABT favored a two-electron transfer pathway, which exhibited a maximum double-layer capacitance of 14.26 mF cm−2, a Tafel slope of 53.01 mV/dec, and a hydrogen peroxide generation rate of 70.3 mmol g−1 h−1. This work underscores the potential of carbazole-based COFs as advanced catalytic materials and offers new insights into the design of metal-free COFs for enhanced catalytic performance.

Zinc Oxide Nanoparticles Treatment Maintains the Postharvest Quality of Litchi Fruit by Inducing Antioxidant Capacity

Pericarp browning and fruit decay severely reduce the postharvest quality of litchi. Improving the antioxidant capacity of the fruit is an effective way to solve these problems. In our study, the appropriate zinc oxide nanoparticles (ZnO NPs) treatment and its mechanism of action on the storability of litchi was investigated. Litchi fruit was soaked in a 100 mg·L−1 ZnO NPs suspension, water, and 500 mg·L−1 prochloraz for 2 min, respectively. The results showed that the ZnO NPs treatment delayed pericarp browning and decay in litchi fruit and was more effective than prochloraz treatment. The ZnO NPs-treated fruit showed significantly increased contents of total anthocyanin, total phenols, and activities of DPPH scavenging, superoxide dismutase, and glutathione peroxidase, as well as the lowest activities of polyphenol oxidase and laccase. ZnO NPs generated hydrogen peroxide and superoxide anion radicals, which were beneficial in slowing down the decay and inducing antioxidant capacity. However, these reactive oxygen species also consumed catalase, peroxidase, glutathione, and glutathione peroxidase. This means that litchi should be treated with an appropriate concentration of ZnO NPs. We concluded that treatment with a 100 mg·L−1 ZnO NPs suspension could induce antioxidant capacity, which is a promising and effective method to maintain the postharvest quality of litchi.

Multifunctional Hydrogel Containing Oxygen Vacancy‐Rich WOx for Synergistic Photocatalytic O2 Production and Photothermal Therapy Promoting Bacteria‐Infected Diabetic Wound Healing

AbstractAn effective method capable of simultaneously providing antibacterial activity, blood glucose regulation, and angiogenesis promotion for healing bacteria‐infected diabetic wounds is not reported to date, but urgently required. In this study, a hydrogel composite (γ‐PGA/PDA/GOx/WOx (PPGW)), endowed with these desired attributes is fabricated by incorporating polydopamine (PDA), glucose oxidase (GOx), and tungsten oxide (WOx) nanowires into the poly(γ‐glutamic acid) (γ‐PGA) framework. The exceptional photothermal conversion properties of PDA facilitated notable antibacterial effects on bacteria‐infected diabetic wounds; GOx regulated high blood glucose by consuming glucose and generating hydrogen peroxide (H2O2); while WOx nanowires displayed remarkable photocatalytic abilities, converting H2O2 into oxygen (O2) when exposed to 808‐nm near‐infrared radiation. Density functional theory calculations and experiments are conducted to confirm the mechanism of WOx‐mediated photocatalytic degradation of H2O2 to produce O2. These transformations aided in alleviating the hypoxic conditions in wounds associated with diabetes, expediting angiogenesis, and fostering cell crawling and proliferation. Consequently, the multifunctional hydrogel dressing PPGW, featuring photothermal, antibacterial, and enzyme‐catalyzed activity reduces hyperglycemia at the wound site. Moreover, photocatalytic O2 production represents a promising strategy for addressing chronic bacteria‐infected diabetic wounds.

Change in components by pretreatments alters the antimicrobial activity of Strobilanthes cusia biomass

The plant Strobilanthes cusia contains various antibacterial components, but the mechanisms behind its antimicrobial activity are not yet fully understood. This study demonstrates that alterations in components due to different pretreatments significantly impacted the antimicrobial activity of S. cusia biomass. Biomass dried using microwave pretreatment, which contained a high amount of indican, exhibited the lowest antibacterial activity, whereas heat-dried biomass without indican showed the highest antibacterial activity. High-performance liquid chromatography analysis indicated that pretreatments influenced the ratios of indican, indoxyl, indigo, and indirubin in S. cusia biomass, likely due to the effect of pretreatments on β-glucosidase activity. Extracts with higher levels of indoxyl, an intermediate product of indican hydrolysis, exhibited stronger inhibitory effects against Staphylococcus aureus. Indoxyl increased the NAD+/NADH ratio, which led to elevated hydrogen peroxide generation and subsequent cell damage. Furthermore, transmission electron microscopy, scanning electron microscopy, and confocal laser scanning microscopy revealed distinct morphological changes in cells exposed to indoxyl. Finally, leveraging the water-soluble properties of indoxyl, we propose a novel approach using microwave drying assisted by β-glucosidase to enhance the antimicrobial activity of S. cusia biomass. These findings provide a theoretical and methodological foundation for the evaluation and future application of S. cusia's bioactive substances.

Constructing boosted charge separation for efficient H2O2 production and pollutant degradation by highly defective ZnIn2S4/ carbon doped boron nitride

Solar-driven photocatalytic production of H2O2 as a promising environmentally-friendly approach has been applied as a chemical reagent and for enhancing photocatalytic remediation. However, this process is still limited by unsatisfactory efficiency and hard separation of photogenerated charge carriers. Herein, we design a dual pathway to improve hydrogen peroxide production by establishing a 2D/2D heterojunction between carbon-doped boron nitride (BCN) and defective zinc indium sulfide (ZIS). The introduction of multiple vacancies and dopants at the interface successfully promoted the interfacial charge transfer and peroxide generation. The Z-scheme heterojunction establishes a built-in electronic field, facilitating continuous electron accumulation and depletion, thereby inducing band bending. As a result, the optimized BCN/ZIS-30 composite (>420 nm wavelength) exhibits 925 μmol/g/h in pure water with no other additions and advances this production to 2006.1 μmol/g/h (2 times as defective ZIS and 12.1 times as BCN) under the existence of isopropanol and aeration. Mechanism investigation indicated that H2O2 is generated via a two-step electron reduction route and water oxidation reaction. The generated H2O2 successfully constructs a self-photo-Fenton system by forming hydroxyl radicals. Accompanied by strong oxygen activation ability, the photo-Fenton system also exhibits rapid degradation of antibiotics with 95 % elimination in 60 minutes. The practical applicability of this photocatalyst was demonstrated through real water remediation tests, exhibiting its effectiveness in removing antibiotics, COD, and total ammonia nitrogen, highlighting its potential for practical water treatment applications. This work provides a novel idea on constructing heterojunction materials for energy saving and water remediation.

Paper immobilized BSA-decorated gold nanoclusters for single-step optical sensing of glucose and cholesterol without cross-reactivity

Minimally invasive methods for detecting glucose, cholesterol and hydrogen peroxide are crucial for monitoring the nutritional and health status of humans and animals. The peroxidase mimetic activity by nanozymes is one of the versatile methods for detecting glucose, cholesterol, hydrogen peroxide, and other biomolecules. However, the strict requirement of acidic pH limits their sensing and interfacing ability with natural enzymes. The present study developed bovine serum albumin (BSA) coated gold nanoclusters (AuNC) immobilized on paper fabric to enable single-step visual detection of glucose, cholesterol and hydrogen peroxide in complex biological fluids like serum and milk. The BSA-AuNC suspension and immobilized paper fabric synergistically interface with the natural oxidative enzymes, glucose oxidase or cholesterol oxidase, at physiological pH. The concomitant loss in the fluorescent intensity of BSA-AuNC-loaded paper fabric exposed to the generated hydrogen peroxide (glucose/glucose oxidase or cholesterol/cholesterol oxidase) was directly proportional to the concentration of glucose or cholesterol. These reactions enabled simple visual detection as well as quantification of hydrogen peroxide, glucose and cholesterol using Image-J software and common smartphone-based mobile applications. The detection ability of BSA-AuNC-embedded paper fabric is specific and remains unaltered in the presence of similar oxidase enzymes or similar substrate analogues. With these unique features, the BSA-AuNC embedded paper fabric stands out as a prominent analytical device with enormous potential as a simple, user-friendly detection tool for monitoring biomolecules that are important to health, nutrition, and environmental safeguarding.

Voltage-Driven Molecular Photoelectrocatalysis of Water Oxidation.

Molecular photocatalysis and photoelectrocatalysis have been widely used to conduct oxidation-reduction processes ranging from fuel generation to electroorganic synthesis. We recently showed that an electrostatic potential drop across the double layer contributes to the driving force for electron transfer (ET) between a dissolved reactant and a molecular catalyst immobilized directly on the electrode surface. In this article, we report voltage-driven molecular photoelectrocatalysis with a prevalent homogeneous water oxidation catalyst, (bpy)Cu (II), which was covalently attached to the carbon surface and exhibited photocatalytic activity. The strong potential dependence of the photooxidation current suggests that the electrostatic potential drop across the double layer contributes to the driving force for ET between a water molecule and the excited state of surface-bound (bpy)Cu (II). Scanning electrochemical microscopy (SECM) was used to analyze the products and determine the faradaic efficiencies for the generation of oxygen and hydrogen peroxide. Unlike electrocatalytic water oxidation by (bpy)Cu (II) in the dark, which produces only O2, the voltage-driven photooxidation includes an additional 2e- pathway generating H2O2. DFT calculations show that the applied voltage and the presence of light can alter the activation energy for the rate-determining water nucleophilic attack steps, thereby increasing the reaction rate of photo-oxidation of water and opening the 2e- pathway. These results suggest a new route for designing next-generation hybrid molecular photo(electro)catalysts for water oxidation and other processes.

Alkali metal cation adsorption–induced surface polarization in polymeric carbon nitride for enhanced photocatalytic hydrogen peroxide production

Photocatalytic hydrogen peroxide (H2O2) generation on the catalyst surface from oxygen is an electron-demanding process, making the construction of an electron-rich surface highly advantageous. In this study, a localized electric field was observed on the surface of polymeric carbon nitride (g-C3N4) when alkali metal cations were adsorbed onto it. These fields effectively inhibited surface carrier recombination and extended their lifespan, thereby enhancing H2O2 production. As a result, g-C3N4 achieved a superior H2O2 yield of 2.25 mM after 1 h in a 0.25 M K+ solution, which was 2.06 times greater than that (1.09 mM) achieved in a pure solvent. Notably, the increase in photocatalytic efficiency showed a remarkable dependence on ion species. At low concentrations, H2O2 generation efficiency was in the order of Li+ < Na+ < K+ < Rb+ < Cs+. However, after optimizing the ion concentration, the highest H2O2 production was achieved in a solution containing K+ instead of Cs+. Molecular dynamics simulations and temperature-dependent photocatalysis experiments revealed that the synergistic interaction between adsorption energy and adsorption distance was crucial in governing the extent to which alkali metal cation adsorption enhanced g-C3N4 photocatalytic H2O2 production. This study provides theoretical insights for the design of materials for electron-demanding photocatalysis and aids in understanding variations in photocatalytic behavior in natural waters.

Novel electrocatalyst with abundant oxygen vacancies enabling efficient two-electron water oxidation reaction for H2O2 synthesis

In the realm of electrocatalytic two-electron water oxidation reaction, the quest for efficient and selective catalysts poses a significant challenge in balancing productivity and activity, hindering the decentralized generation of hydrogen peroxide (H2O2) through electrochemical means. Addressing this hurdle, our study introduces a novel approach to crafting an effective and stable electrocatalyst for the two-electron water oxidation reaction (2e-WOR). Through the synthesis of magnesium stannite tungstate from a mixture of MgSnO3 and WO3, the engineer of a material with abundant oxygen vacancies is crucial for catalytic activity. This catalyst demonstrates exceptional performance, ascribed to its distinctive oxygen vacancies proximal to the active center Sn and electronic modulation by tungsten. Notably, Mg1-xSnWO6-x700 exhibits a remarkably low overpotential of 70 mV at 10 mA cm−2, coupled with a high faradic efficiency of 84 % for 2e- WOR at 2.6 V vs. RHE, maintaining consistent performance over 35 h. Furthermore, the formation of oxygen vacancies and the associated electronic transfer underscore the novelty and promise of our material in advancing the field of two-electron WOR. In sum, our electrocatalyst presents a cost-efficient and selective solution for water oxidation, offering potential avenues for enhancing H2O2 production.