O2 Release Research Articles

Challenges and Modification Strategies on High-Voltage Layered Oxide Cathode for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) have attracted great attention due to their advantages on resource abundance, cost and safety. Layered oxide cathodes (LOCs) of SIBs possess high theoretical capacity, facile synthesis and low cost, and are promising candidates for large scale energy storage application. Increasing operating voltage is an effective strategy to achieve higher specific capacity and also high energy density of SIBs. However, at high operating voltages, LOCs will undergo a series of phase transitions in bulk phase, leading to huge change of volume and layer spacings accompanied by severe lattice stress and cracking formation. Degeneration of surface also occurs between LOCs and electrolytes, resulting in sustained growth of cathode electrolyte interphase (CEI) and release of O2 and CO2. These induce structural destruction and electrochemical performance degradation in high voltage regions. Recently, many strategies have been proposed to improve electrochemical performance of LOCs under high voltages, including bulk element doping, structural design, surface coating and gradient doping. This review describes pivotal challenges and occurrence mechanisms at high voltages, and summarizes strategies to improve stability of bulk and surface. Viewpoints will be provided to promote development of high energy density SIBs.

Gelation embolism agents suppress clinical TACE-incited pro-metastatic microenvironment against hepatocellular carcinoma progression

Current embolic agents in transcatheter arterial chemoembolization (TACE) of hepatocellular carcinoma (HCC) encounter instability and easy leakage, discounting TACE efficacy with residual HCC. Moreover, clinical TACE aggravates hypoxia and pro-metastatic microenvironments, rendering patients with HCC poor prognosis. Herein, we developed Zein-based embolic agents that harness water-insoluble but ethanol-soluble Zein to encompass doxorubicin (DOX)-loaded mesoporous hollow MnO2 (HMnO2). The conditions and capacity of HMnO2 to generate reactive oxygen species (ROS) were assayed. Mechanical examinations of Zein-HMnO2@DOX were performed to evaluate its potential as the embolic agent. Invitro experiments were carried out to evaluate the effect of Zein-HMnO2@DOX on HCC. The subcutaneous HCC mouse model and rabbit VX2 HCC model were established to investigate its anti-tumor and anti-metastasis efficacy and explore its potential anti-tumor mechanism. The high adhesion and crosslinking of Zein with HMnO2@DOX impart Zein-HMnO2@DOX with strong mechanical strength to resist deformation and wash-off. Zein gelation and HMnO2 decomposition in response to water and acidic tumor microenvironment, respectively, enable continuous DOX release and Fenton-like reaction for reactive oxygen species (ROS) production and O2 release to execute ROS-enhanced TACE. Consequently, Zein-based embolic agents outperform clinically-used lipiodol to significantly inhibit orthotopic HCC growth. More significantly, O2 release down-regulates hypoxia inducible factor (HIF-1α), vascular endothelial growth factor (VEGF) and glucose transporter protein 1 (GLUT1), which thereby re-programmes TACE-aggravated hypoxic and pro-metastatic microenvironments to repress HCC metastasis towards lung. Mechanistic explorations uncover that such Zein-based TACE agents disrupt oxidative stress, angiogenesis and glycometabolism pathways to inhibit HCC progression. This innovative work not only provides a new TACE agent for HCC, but also establishes a new strategy to ameliorate TACE-aggravated hypoxia and metastasis motivation against clinically-common HCC metastasis after TACE operation. Excellent Young Science Fund for National Natural Science Foundation of China (82022033); National Natural Science Foundation of China (Grant No. 82373086, 82102761); Major scientific and technological innovation project of Wenzhou Science and Technology Bureau (Grant No. ZY2021009); Shanghai Young Top-Notch Talent.

The Switching of the Type of a ROS Signal from Mitochondria: The Role of Respiratory Substrates and Permeability Transition

Flashes of superoxide anion (O2−) in mitochondria are generated spontaneously or during the opening of the permeability transition pore (mPTP) and a sudden change in the metabolic state of a cell. Under certain conditions, O2− can leave the mitochondrial matrix and perform signaling functions beyond mitochondria. In this work, we studied the kinetics of the release of O2− and H2O2 from isolated mitochondria upon mPTP opening and the modulation of the metabolic state of mitochondria by the substrates of respiration and oxidative phosphorylation. It was found that mPTP opening leads to suppression of H2O2 emission and activation of the O2− burst. When the induction of mPTP was blocked by its antagonists (cyclosporine A, ruthenium red, EGTA), the level of substrates of respiration and oxidative phosphorylation and the selective inhibitors of complexes I and V determined the type of reactive oxygen species (ROS) emitted by mitochondria. It was concluded that upon complete and partial reduction and complete oxidation of redox centers of the respiratory chain, mitochondria emit H2O2, O2−, and nothing, respectively. The results indicate that the mPTP- and substrate-dependent switching of the type of ROS leaving mitochondria may be the basis for O2−- and H2O2-selective redox signaling in a cell.

Atomically Dispersed Vanadium-Induced Ru-V Dual Active Sites Enable Exceptional Performance for Acidic Water Oxidation.

Regulating the catalytic reaction pathway to essentially break the activity/stability trade-off that limits RuO2 and thus achieves exceptional stability and activity for the acidic oxygen evolution reaction (OER) is important yet challenging. Herein, we propose a novel strategy of incorporating atomically dispersed V species, including O-bridged V dimers and V single atoms, into RuO2 lattices to trigger direct O-O radical coupling to release O2 without the generation of *OOH intermediates. Vn-RuO2 showed high activity with a low overpotential of 227 mV at 10 mA cm-2 and outstanding stability during a 1050 h test in acidic electrolyte. Operando spectroscopic studies and theoretical calculations revealed that compared with the V single atom-doping case, the introduction of the V dimer into RuO2 further decreases the Ru-V atomic distance and weakens the adsorption strength of the *O intermediate to the active V site, which supports the more energetically favorable oxygen radical coupling mechanism (OCM). Furthermore, the highly asymmetric Ru-O-V local structure stabilizes the surface Ru active center by lowering the valence state and increasing the resistance against overoxidation, which result in outstanding stability. This study provides insight into ways of increasing the intrinsic catalytic activity and stability of RuO2 by atomically dispersed species modification.

Atomically Dispersed Vanadium‐Induced Ru‐V Dual Active Sites Enable Exceptional Performance for Acidic Water Oxidation

AbstractRegulating the catalytic reaction pathway to essentially break the activity/stability trade‐off that limits RuO2 and thus achieves exceptional stability and activity for the acidic oxygen evolution reaction (OER) is important yet challenging. Herein, we propose a novel strategy of incorporating atomically dispersed V species, including O‐bridged V dimers and V single atoms, into RuO2 lattices to trigger direct O−O radical coupling to release O2 without the generation of *OOH intermediates. Vn−RuO2 showed high activity with a low overpotential of 227 mV at 10 mA cm−2 and outstanding stability during a 1050 h test in acidic electrolyte. Operando spectroscopic studies and theoretical calculations revealed that compared with the V single atom‐doping case, the introduction of the V dimer into RuO2 further decreases the Ru‐V atomic distance and weakens the adsorption strength of the *O intermediate to the active V site, which supports the more energetically favorable oxygen radical coupling mechanism (OCM). Furthermore, the highly asymmetric Ru−O−V local structure stabilizes the surface Ru active center by lowering the valence state and increasing the resistance against overoxidation, which result in outstanding stability. This study provides insight into ways of increasing the intrinsic catalytic activity and stability of RuO2 by atomically dispersed species modification.

Fabrication of polyoxometalate dispersed cobalt oxide nanowires for electrochemically monitoring superoxide radicals from Hela cell mitochondria

An ultrasensitive electrochemical sensor is constructed by electrostatically adsorbing negatively charged hourglass-shape Cu-Polyoxometalate (POM) onto a positively charged CoO nanowires modified carbon cloth. The petaloid CoO nanowires have a large specific surface area that can well disperse open-structured Cu-POM to form Cu-POM@CoONWs@CC, which can maximumly expose catalytic active centers (Co2+ and Cu2+) and accelerate mass/charge transfer. In addition to the above advantages, the excellent electron exchange ability of Cu-POM and good conductivity of CoONWs@CC endow the sensor with good detection capability to H2O2 including a linear detection range of 0.05–1.4 μA μM−1, a low detection limit of 0.022 μM, high sensitivity of 110.48 μA μM−1, good selectivity and long-term stability. Due to the fast transformation of superoxide anion (O2∙‐) to H2O2, the sensor can indirectly monitor the electron leakage resulting in the formation of O2∙‐ via detecting H2O2. Afterwards, Hela cell mitochondria were extracted from the living cells that cultured with different mitochondrial inhibitors and the release of O2∙‐ from the corresponding mitochondrial complexes was monitored by the sensor. Through comparing the current signals, we determined that complex I is probably the main electron leakage site. This work could provide meaningful information for the diagnosis of certain oxidative stress diseases.

Sequential oxygen evolution and decoupled water splitting via electrochemical redox reaction of nickel hydroxides

Alkaline water electrolysis is a promising low-cost strategy for clean and sustainable hydrogen production but is largely limited by the sluggish anodic oxygen evolution reaction and the challenges in maintaining adequate separation between H2 and O2. Here, we reveal an anodic-cathodic sequential oxygen evolution process via electrochemical oxidation and subsequent reduction of Ni hydroxides, enabling much lower overpotentials than conventional anodic oxygen evolution. By using (isotope-labeled) differential electrochemical mass spectrometry and in situ Raman spectroscopy combined with density functional theory calculations, we evidence that the sequential oxygen evolution originates from the electrochemical oxidation of Ni hydroxides to NiOO– active species while undergoing a different, reductive step of NiOO– for the final release of O2 due to weakened Ni–O covalency. Based on this sequential process, we propose and demonstrate a hybrid water electrolysis and energy storage device, which enables time-decoupled hydrogen and oxygen evolution and electrochemical energy storage in the Ni hydroxides.

Gradient and De-Clustered Anionic Redox Enabled Undetectable O2 Formation in 4.5V Sodium Manganese Oxide Cathodes.

Anionic redox chemistry presents a promising approach to enhancing the energy density of oxide cathode materials. However, anionic redox reactions invariably lead to O2 formation, either as free gaseous O2 or trapped molecular O2, which destabilizes the material's structure. Here, this critical challenge is addressed by constructing a crystal structure with both gradient redox activity and de-clustered redox-active oxygen. This design strategy is directly validated by operando differential electrochemical mass spectrometry and ex situ 50K electron paramagnetic resonance, revealing no release of O2 or trapped O2 in the 4.5V P2-type sodium manganese-based layered oxide. Notably, the material exhibits a highly reversible capacity of 247mAhg-1 at 20mAg-1 and exceptional capacity retention of 91.4% after 300 cycles at 300mAg-1. In situ X-ray diffraction further suggests that the absence of O2 formation suppresses the typical P2-O2 phase transition, resulting in a minimal lattice volume change of only 0.5%. Ex situ neutron diffraction studies and theoretical calculations further elucidate that the locally ordered lattice is well-preserved, attributable to reduced cationic migrations during cycling.

Blood-Brain Barrier-Penetrating Metal-Organic Framework Antioxidant Nanozymes for Targeted Ischemic Stroke Therapy.

Overproduction of reactive oxygen species (ROS) during reperfusion in ischemic stroke (IS) severely impedes neuronal survival and results in high rates of morbidity and disability. The effective blood-brain barrier (BBB) penetration and brain delivery of antioxidative agents remain the biggest challenge in treating ischemic reperfusion-induced cerebrovascular and neural injury. In this study, a metal-organic framework (MOF) nanozyme (MIL-101-NH2(Fe/Cu)) with ROS scavenging activities to encapsulate neuroprotective agent rapamycin is fabricated and decorating the exterior with BBB-targeting protein ligands (transferrin), thereby realizing enhanced drug retention and controlled release within ischemic lesions for the synergistic treatment of IS. Through the receptor-mediated transcellular pathway, the transferrin-coated MOF nanoparticles achieved efficient transport across the BBB and targeted accumulation at the cerebral ischemic injury site of mice with middle cerebral artery occlusion/reperfusion (MCAO/R), wherein the nanocarrier exhibited catalytic activities of ROS decomposition into O2 and H2O2-responsive rapamycin release. By its BBB-targeting, antioxidative, anti-inflammatory, and antiapoptotic properties, the MOF nanosystem addressed multiple pathological factors of IS and realized remarkable neuroprotective effects, leading to the substantial reduction of cerebral infarction volume and accelerated recovery of nerve functions in the MCAO/R mouse model. This MOF-based nanomedicine provides valuable design principles for effective IS therapy with multi-mechanism synergies.

Effect of Rare Earth Ion Doping on the Performance of Lithium-Rich Cathode Materials for Lithium-Ion Batteries

Lithium-rich layered oxide cathode materials have the advantages of a high voltage and a high specific capacity. Their commercial applications have however been impeded by some disadvantages such as low initial coulombic efficiency and low cycle life. To overcome these issues, rare earth ion-doped lithium-rich layered oxide cathode materials are investigated in this work. The irreversible release of O2- in Li2MnO3 is suppressed by rare earth ions doping, which enhanced the initial coulombic efficiency of the materials. Meanwhile, the rare-earth ion radius used for doping is larger than the Mn4+ radius, which enlarges the (003)-crystalline plane spacing, resulting in a significant enhancement of the rate performance of the material.

Structure‐Based Design and in‐Flow Synthesis of Aromatic Endoperoxides Acting as Oxygen Releasing Agents

AbstractHypoxia occurs in different pathological settings as a consequence of poor vascularization, and it results in reduced efficacy of some current nosocomial treatments i. e. chemotherapy and photodynamic therapy. In order to overcome these boundaries, aromatic endoperoxides (EPOs) have been studied and proposed as oxygen‐releasing agents (ORAs) due to their ability to reversibly bind molecular oxygen (O2), liberating it upon suitable triggering. DFT calculation of the dissociation energy (Ediss) of the intramolecular O−O bridge and structural crystallographic data of synthesized and studied EPOs drove the design of an array of 9,10‐disubstituted anthracenes among which three candidates were carefully selected. Once optimized the synthesis of the aromatic substrates, for the first time the corresponding EPOs have been produced under continuous flow irradiation in the presence of a sub‐stoichiometric amount of a photosensitizer in organic solvents. The release of O2 could be obtained straightforwardly at 37.5 °C by thermolysis. In accordance with the calculated Ediss=3.2 kcal mol−1 and an experimental t1/2=40 minutes, 3,3′‐(anthracene‐9,10‐diyl)bis(prop‐2‐yn‐1‐ol) resulted as the best candidate for the sustained release of O2 under physiologically relevant conditions. Its exploitation as ORA to relieve hypoxia will be evaluated and described in due course.

Theoretical-level insights on the molecular structures and LiCl dopant of carbon nitride single crystals for solar-driven overall water splitting

Addressing energy and environmental challenges requires sustainable technologies like photocatalytic overall water splitting (OWS) using graphitic carbon nitride (GCN). This study investigates the molecular structures and LiCl doping effects in GCN variants-poly(triazine imide) intercalated with LiCl (PTI/Li+Cl-), and heptazine-based crystalline GCN (HCCN)-to understand their suitability for OWS. Experimental results show that PTI/Li+Cl- exhibits superior OWS activity, producing 802.3 μmol h-1 gcat-1 of H₂ and 395.6 μmol h-1 gcat-1 of O₂, due to its active planes and favorable electron transfer. In contrast, HCCN shows high H₂ production but no O₂ release. Density functional theory calculations reveal that triazine structures are more favorable for oxygen evolution reaction (OER) while heptazine structures excel in hydrogen evolution reaction (HER). LiCl doping can enhance OWS performance by improving electronic conductivity and reducing reaction activation energy. The results encourage the combination of triazine and heptazine structures with LiCl doping to optimize OWS, offering a theoretical basis for designing efficient GCN-based photocatalysts.

A Self-Catalytic NO/O2 Gas-Releasing Nanozyme for Radiotherapy Sensitization through Vascular Normalization and Hypoxia Relief.

Radiotherapy (RT), essential for treating various cancers, faces challenges from tumor hypoxia, which induces radioresistance. A tumor-targeted "prosthetic-Arginine" coassembled nanozyme system, engineered to catalytically generate nitric oxide (NO) and oxygen (O2) in the tumor microenvironment (TME), overcoming hypoxia and enhancing radiosensitivity is presented. This system integrates the prosthetic heme of nitric oxide synthase (NOS) and catalase (CAT) with NO-donating Fmoc-protected Arginine and Ru3+ ions, creating HRRu nanozymes that merge NOS and CAT functionalities. Surface modification with human heavy chain ferritin (HFn) improves the targeting ability of nanozymes (HRRu-HFn) to tumor tissues. In the TME, strategic arginine incorporation within the nanozyme allows autonomous O2 and NO release, triggered by endogenous hydrogen peroxide, elevating NO and O2 levels to normalize vasculature and improve blood perfusion, thus mitigating hypoxia. Employing the intrinsic O2-transporting ability of heme, HRRu-HFn nanozymes also deliver O2 directly to the tumor site. Utilizing esophageal squamous cell carcinoma as a tumor model, the studies reveal that the synergistic functions of NO and O2 production, alongside targeted delivery, enable the HRRu-HFn nanozymes to combat tumor hypoxia and potentiate radiotherapy. This HRRu-HFn nanozyme based approach holds the potential to reduce the radiation dose required and minimize side effects associated with conventional radiotherapy.

Simultaneously inhibit cadmium and arsenic uptake in rice (Oryza sativa L.) by Selenium enhanced iron plaque: Performance and mechanism

Selenium (Se) fortification is witnessed to simultaneously inhibit absorbing Cadmium (Cd) and Arsenic (As) by rice plants, but the mechanism is unclear. Here, the effects of Se on the root morphology, iron plaque (IP) content, soil Fe2+ content, radial oxygen loss (ROL), and enzyme activities of the rice plants in the soil contaminated by Cd and As were intensively investigated through the hydroponic and soil experiments. Se effectively alleviated the toxic effects of Cd and As on the plants and the dry weight, root length, and root width were increased by 203.18%, 33.41%, and 52.81%, respectively. It also elucidated that ROL was one of the key factors to elevate IP formation by Se and the specific pathways of Se enhancing ROL were identified. ROL of the plants in the experiment group treated by Se was increased 36.76%, and correspondingly IP was magnified 50.37%, compared to the groups with Cd and As. It was owing to Se significantly increased the root porosity (62.11%), facilitating O2 transport to the roots. Additionally, Se enhanced the activities of catalase (CAT) and superoxide dismutase (SOD) to promote the catalytic degradation of ROS induced by Cd and As stress. It indirectly increased O2 release in the rhizosphere, which benefit to form more robust IP serve as stronger barrier to Cd and As. The results of our study provide a novel molecular level insight for Se promoting root IP to block Cd and As uptake by the rice plants.

Closing Kok’s cycle of nature’s water oxidation catalysis

The Mn4CaO5(6) cluster in photosystem II catalyzes water splitting through the Si state cycle (i = 0–4). Molecular O2 is formed and the natural catalyst is reset during the final S3 → (S4) → S0 transition. Only recently experimental breakthroughs have emerged for this transition but without explicit information on the S0-state reconstitution, thus the progression after O2 release remains elusive. In this report, our molecular dynamics simulations combined with density functional calculations suggest a likely missing link for closing the cycle, i.e., restoring the first catalytic state. Specifically, the formation of closed-cubane intermediates with all hexa-coordinate Mn is observed, which would undergo proton release, water dissociation, and ligand transfer to produce the open-cubane structure of the S0 state. Thereby, we theoretically identify the previously unknown structural isomerism in the S0 state that acts as the origin of the proposed structural flexibility prevailing in the cycle, which may be functionally important for nature’s water oxidation catalysis.

Unraveling the oxygen evolution in layered LiNiO2 with the role of Li/Ni disordering

Oxygen loss is widely recognized as a major factor in the structural degradation of Ni-rich layered cathode materials, while a study on the detailed oxygen evolution process and the role of inevitable Li/Ni disordering defects is still lacking. Using ab initio calculations with van der Waals correction, we performed an in-depth study on the oxygen evolution in layered LiNiO2 and considered the role of Li/Ni disordering. We find that excess Ni in Li slab act as a pillar role for the structural framework and increases bond strength of adjacent oxygen ions, both of which are beneficial to the thermal and kinetic stability of lattice oxygen in LiNiO2, thus inhibiting the oxygen evolution. For Li/Ni exchange and Excess Li defects, the Li ion in Ni slab preferred to return to the vacancy in Li slab with delithiation in both surface and bulk LiNiO2. This situation induces the weaken binding and fast migration of lattice oxygen, even Ni slab collapse and oxygen release in the surface. Furthermore, the ab-initio molecular dynamics simulations for LiNiO2 surface reveal three stages of oxygen loss in the pristine state: (i) the formation of pre-O-O dimer; (ii) the pre-O-O dimer oxidizing to O-O dimer; (iii) O2 release with oxygen oxidation and Ni migration. The Li/Ni exchange and Excess Li defects accelerate this process because of Li ion in Ni slab returning to Li slab, while the Excess Ni defects will inhibit this process. We hope this work will improve the understanding of oxygen evolution in layered LiNiO2 and provide theoretical guidance for the design of Ni-rich layered cathode materials with improved stability.

The Effect of Co-Delivery of Oxygen and Anticancer Drugs on the Viability of Healthy and Cancer Cells under Normoxic and Hypoxic Conditions.

Hypoxia, cancer, tissue damage, and acidic pH conditions are interrelated, as chronic hypoxic conditions enhance the malignant phenotype of cancer cells, causing more aggressive tissue destruction, and hypoxic cells rely on anaerobic glycolysis, leading to the accumulation of lactic acid. Therefore, the administration of oxygen is necessary to support the functions of healthy cells until the formation of new blood vessels and to increase the oxygen supply to cancerous tissues to improve the efficacy of antitumor drugs on tumor cells. In addition to O2 supply, pH-dependent delivery of anticancer drugs is desired to target cancer cells and reduce drug side effects on healthy cells. However, the simultaneous delivery of O2 and pH-dependent anticancer drugs via nanomaterials and their effects on the viability of normal and cancer cells under hypoxic conditions have not been studied in sufficient numbers. This study describes the synthesis of a pH-responsive nanomaterial containing oxygen and anticancer drugs that exhibits sustained O2 release over a 14 d period under hypoxic conditions and pH-dependent sustained release of anticancer drugs over 30 d. The simultaneous administration of O2 and anticancer drugs results in higher cell survival of normal cells than that of cancer cells under hypoxic and normoxic conditions.

The Effect of Removal of External Proteins PsbO, PsbP and PsbQ on Flash-Induced Molecular Oxygen Evolution and Its Biphasicity in Tobacco PSII.

The oxygen evolution within photosystem II (PSII) is one of the most enigmatic processes occurring in nature. It is suggested that external proteins surrounding the oxygen-evolving complex (OEC) not only stabilize it and provide an appropriate ionic environment but also create water channels, which could be involved in triggering the ingress of water and the removal of O2 and protons outside the system. To investigate the influence of these proteins on the rate of oxygen release and the efficiency of OEC function, we developed a measurement protocol for the direct measurement of the kinetics of oxygen release from PSII using a Joliot-type electrode. PSII-enriched tobacco thylakoids were used in the experiments. The results revealed the existence of slow and fast modes of oxygen evolution. This observation is model-independent and requires no specific assumptions about the initial distribution of the OEC states. The gradual removal of exogenous proteins resulted in a slowdown of the rapid phase (~ms) of O2 release and its gradual disappearance while the slow phase (~tens of ms) accelerated. The role of external proteins in regulating the biphasicity and efficiency of oxygen release is discussed based on observed phenomena and current knowledge.

Origin of O2 Generation in Sulfide-Based All-Solid-State Batteries and its Impact on High Energy Density.

The cathode surface of sulfide-based all-solid-state batteries (SBs) is commonly coated with amorphous-LiNbO3 in order to stabilize charge-discharge reactions. However, high-voltage charging diminishes the advantages, which is caused by problems with the amorphous-LiNbO3 coating layer. This study has investigated the degradation of amorphous-LiNbO3 coating layer directly during the high-voltage charging of SBs. O2 generation via Li extraction from the amorphous-LiNbO3 coating layer is observed using electrochemical gas analysis and electrochemical X-ray photoelectron spectroscopy. This O2 leads to the formation of an oxidative solid electrolyte (SE) around the coating layer and degrades the battery performance. On the other hand, elemental substitution (i.e., amorphous-LiNbxP1- xO3) reduces O2 release, leading to stable high-voltage charge-discharge reactions of SBs. The results have emphasized that the suppression of O2 generation is a key factor in improving the energy density of SBs.

Oxidation and mineralization rates of harmful organic chemicals in hydroxyl radical induced reactions

In most of advanced oxidation processes (AOPs) used to destroy harmful organic chemicals in water/wastewater hydroxyl radical (•OH) reactions oxidize (increasing the oxygen/carbon ratio in the molecules) and mineralize (transforming them to inorganic molecules, H2O, CO2, etc.) these contaminants. In this paper, we used the radiolysis of water to produce •OH and characterised the rate of oxidation and mineralization by the dose dependences of the Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) content values. Analysis of the dose dependences for 34 harmful organic compounds showed large differences in the oxidation and mineralization rates and these parameters are characteristic to the given group of chemicals. E.g., the rate of oxidation is relatively low for fluoroquinolone antibiotics; it is high for β-blocker medicines. Mineralization rates are low for both fluoroquinolones and β-blockers. The one-electron-oxidant •OH in most cases induces two − four-electron-oxidations. Most of the degradation takes place gradually, through several stable molecule intermediates. However, based on the results it is likely, that some part of the oxidation and mineralization takes place parallel. The organic radicals formed in •OH reactions react with several O2 molecules and release several inorganic fragments during the radical life cycle.