Oxygen Reduction Process Research Articles

Time-dependent corrosion behavior of EH36 steel caused by Pseudomonas aeruginosa based on big data monitoring technology

Marine microbial corrosion poses a significant threat to the safe service of marine engineering equipment. Previous studies have often failed to thoroughly analyze the continuous and prolonged microbial corrosion process, resulting in an incomplete understanding of microbial corrosion mechanisms involved at various stages and the development of ineffective control strategies. This study employed a corrosion big data online real-time monitoring technique to investigate the time-dependent corrosion behavior of EH36 steel caused by Pseudomonas aeruginosa in aerobic environments over a 30-d incubation period. It was found that P. aeruginosa accelerated the corrosion of EH36 steel in the early stages by enhancing the cathodic oxygen reduction process. As oxygen levels declined, P. aeruginosa transitioned from aerobic to anaerobic respiration, promoting corrosion through biocatalytic nitrate reduction. In the later stages, the reduction in sessile cell counts, extreme low oxygen concentration, and dense surface film increased the charge transfer and film resistances, ultimately leading to corrosion inhibition. The weight loss and electrochemical data confirmed the effectiveness of the big data monitoring technique in investigating microbial corrosion, which provides new approaches for diagnosing and preventing microbial corrosion.

Room temperature oxygenated groups addition in carbon materials via ozone oxidation for boosting electrochemical H2O2 production

The crucial yet delicate 2e− oxygen reduction reaction (ORR) for producing the green chemical H2O2 relies on the uniform coordination environment of the active sites, such as oxygenated groups in metal-free carbon material catalysts. However, conventional harsh carbon material synthesis methods inevitably introduce structural defects and alter morphology, hindering the precise control of active site formation. Herein, we developed the ozone oxidation method under controlled reaction conditions to precisely modify carbon materials at room temperature. Through controlling the ozonation of reaction time, concentration, temperature, and relative humidity, we find the mild method allows us to precisely add active carboxyl group (–COOH) without forming structural defects. Electrochemical tests reveal that the optimal catalyst with the highest –COOH content exhibits the most outstanding mass activity of 164 A/g at 0.65 V and the highest H2O2 selectivity of 91 %. The density functional theory calculations demonstrate that the carbon sites directly connected to –COOH possess the optimized binding strength of *OOH intermediate to favor the two-electron oxygen reduction process. This work offers a novel approach to precisely and gently control carbon surface groups while preserving the structural morphology through ozone gas treatment, which can be readily applied to other material designs.

Undervalued role of metal-carbon junction in selective generation of H2O2: An example of the zinc-carbon junction edge providing asymmetric active sites for efficient oxygen reduction

The spontaneous oxygen reduction is a potential technology for in-situ H2O2 production, which gets rid of the dependence on electricity and solar energy. Previous some metal–carbon compounds reported are feasible to trigger oxygen reduction. These reports always claim the high H2O2 generation ability of metal–carbon composites, while rarely discuss the contribution of carbon and the carbon–metal junction to the oxygen reduction process. Inspired by the dual active sites, we infer that the role of interfacial carbon in metal–carbon composites is underestimated. By a heat treatment of the co-precipitate of zinc and glucose, the Zn-C junction is constructed in Zn-gc to achieve a spontaneous selective reduction of O2 to H2O2. The Zn-C interface edge is active site, where an asymmetric activation is achieved by bonding two O atoms from O2 to C and Zn, respectively. The Zn traction to one of the O atoms is mainly in xy plane, while the C traction to the other O atom is parallel to z-axis. The yield of H2O2 produced per gram of Zn increases from 27.89 mg to 122.21 mg, an improvement of 4.38 times. And the inertness of Zn and its oxygen-containing compounds towards H2O2 enables Zn-gc/O2 system to stabilize H2O2 over a long period of time. This work reveals the crucial role of neglected junction interfaces in oxygen reduction reactions in metal–carbon composites.

Bifunctional 0D carbon quantum dot cathode electrocatalyst coupled with atomic hydrogen and hydroxyl radicals for efficient removal of oxytetracycline hydrochloride

Efficient removal of antibiotics is difficult to achieve by conventional single-oxidation or reduction processes. Herein, a bifunctional cathodic electrocatalyst coupling atomic hydrogen (H*) reduction with hydroxyl radical (·OH) oxidation in an efficient electrocatalytic process was developed for the effective degradation of oxytetracycline hydrochloride (OTC). Pd particles were dispersed on B-doped carbon quantum dots to prepare a Pd-B-doped carbon quantum dots/titanium (Pd-BCQD/Ti) electrode as a bifunctional cathode catalyst. The electrode can simultaneously generate H* through the H2O/H+ reduction process, H2O2 through the oxygen reduction process, and then generate ·OH. H* performs nucleophilic hydrogenation reduction of OTC molecules, and ·OH performs electrophilic oxidation of the carbon skeleton, and both act synergistically with the active chlorine species (HClO) generated at the anode. The experimental results showed that the electrode achieved 90.50 % removal of OTC within 60 min. In addition, the Pd-BCQD/Ti electrode reduces energy consumption while increasing current efficiency. The degradation effect was more than 85.80 % in the pH range of 3∼9, indicating fairly stable catalytic activity over a wide pH range. The degradation efficiency was basically unchanged after ten cycles, and the reactivity was still high in the actual water. Intermediates were analyzed based on LC-MS to explore the degradation pathways of OTC. The toxicity of the intermediates generated during OTC degradation was predicted based on quantitative conformational relationships. This study provides a feasible strategy for the preparation of bifunctional catalysts based on zero-dimensional BCQD for efficient green antibiotic wastewater treatment.

LaCo0.2Fe0.8O3 perovskites doped with natural Ca2+ as bifunctional electrocatalysts for oxygen evolution and reduction reactions.

Perovskite oxides are promising electrocatalysts for various energy applications due to their exceptional catalytic activity, flexible architecture, and low cost. In this study, LCFO was doped with different ratios of Ca2+ from eggshells, resulting in dual-purpose electrocatalysts for oxygen reduction and evolution processes. The nanoparticles were characterized using various techniques, including Brunauer-Emmett-Teller analysis and XRD. Results clarified the relative surface area and roughness, increasing with Ca2+ doping. LCFO also demonstrated highly magnetic properties, improved charge transfer, catalytic activity, and long-term durability. The results demonstrated the perovskite's cost-effectiveness as a bifunctional electrocatalyst, and the role of Ca2+ in enhancing its properties. La0.6Ca0.4Co0.2Fe0.8O3(LCCFO-0.4) showed higher magnetic properties (M s = 13.36 emu g-1 and M r = 2.54 emu g-1). The LCFO sample showed a current density of 5.13 mA cm-2 and 3 mA cm-2 for OER and ORR respectively, at E onset 1.7 V and 0.57 V (vs. RHE). The LCFO electrochemical active surface area is 0.033 cm2.

A review on carbonaceous materials for fuel cell technologies: An advanced approach

AbstractIn the context of sustainable development environment‐friendly approaches, technologies have gained momentum with dual objective of achieving technological advancements and innovations through green energy source. One such approach is fuel cells which have been identified as a potential source for the production of electric power from chemical fuels. Fuel cell has become popular as they represent environmentally friendly method to generate power. The trucking industry and fleet transit networks have shown the potential of the hydrogen fuel cell despite many obstacles, such as material composition, storage, and distribution, because it can be used and moved securely, leading to a significant reduction in CO2 and particulate pollution. Proton exchange membrane fuel cells (PEMFC) are the subject of intense research in environmental friendly power transformation and storing tools as a consequence of environmental friendliness, minimal emissions, and great effectiveness. Fuel cell transportation is successful with oxygen reduction process (ORR). Graphite, a highly organized type of carbon, serves as the standard due to its durability and accessibility. This article focuses on the evolution of electrodes as well as electrolytic materials or fluid materials for various kinds of fuel cells and also explains the uses, difficulties, advancements, etc. pertaining to electrodes and fluids of diverse types of fuel cells.

Hierarchical multi-task deep learning-assisted construction of human gut microbiota reactive oxygen species-scavenging enzymes database.

In the process of oxygen reduction, reactive oxygen species (ROS) are generated as intermediates, including superoxide anion (O2-), hydrogen peroxide (H2O2), and hydroxyl radicals (OH-). ROS can be destructive, and an imbalance between oxidants and antioxidants in the body can lead to pathological inflammation. Inappropriate ROS production can cause oxidative damage, disrupting the balance in the body and potentially leading to DNA damage in intestinal epithelial cells and beneficial bacteria. Microorganisms have evolved various enzymes to mitigate the harmful effects of ROS. Accurately predicting the types of ROS-scavenging enzymes (ROSes) is crucial for understanding the oxidative stress mechanisms and formulating strategies to combat diseases related to the "gut-organ axis." Currently, there are no available ROSes databases (DBs). In this study, we propose a systematic workflow comprising three modules and employ a hierarchical multi-task deep learning approach to collect, expand, and explore ROSes-related entries. Based on this, we have developed the human gut microbiota ROSes DB (http://39.101.72.186/), which includes 7,689 entries. This DB provides user-friendly browsing and search features to support various applications. With the assistance of ROSes DB, various communication-based microbial interactions can be explored, further enabling the construction and analysis of the evolutionary and complex networks of ROSes DB in human gut microbiota species.IMPORTANCEReactive oxygen species (ROS) is generated during the process of oxygen reduction, including superoxide anion, hydrogen peroxide, and hydroxyl radicals. ROS can potentially cause damage to cells and DNA, leading to pathological inflammation within the body. Microorganisms have evolved various enzymes to mitigate the harmful effects of ROS, thereby maintaining a balance of microorganisms within the host. The study highlights the current absence of a ROSes DB, emphasizing the crucial importance of accurately predicting the types of ROSes for understanding oxidative stress mechanisms and developing strategies for diseases related to the "gut-organ axis." This research proposes a systematic workflow and employs a multi-task deep learning approach to establish the human gut microbiota ROSes DB. This DB comprises 7,689 entries and serves as a valuable tool for researchers to delve into the role of ROSes in the human gut microbiota.

Amino-Induced Modulation of Electronic State and Neighboring Site Distance through Second Shell Boosted Catecholase-Mimicking Activity of Electron-Rich Cu Center.

Boosting the biomimetic catalytic activity of nanozyme is important for its potential application. One common strategy to achieve this goal mainly focused on manipulating the electronic state of metal site through the first coordination shell to modulate the adsorption/desorption strength of related reactant, intermediate and/or product, but remained challenging. Taking Cu-based catecholase-mimicking nanozyme for example, this work herein reports a different strategy involving amino-induced modulation of electronic state through the second shell to raise the electron density of Cu site, which further triggers the repulsion effect between neighboring geminal Cu centers to increase the Cu─Cu distance. The resulting nanozyme with electron-rich Cu site (DT-Cu) presents a lower work function and an upshifted d-band center in comparison with its counterpart (i.e., relatively electron-deficient TA-Cu), which promotes the electron transfer and enhances the adsorption strengths of Cu site for O2, catechol and H2O2 intermediate. The longer Cu─Cu distance of DT-Cu accelerated the O─O bond dissociation of H2O2 intermediate. This expedites the oxygen reduction process during catecholase-like catalysis, which together with the enhanced O2/H2O2/catechol adsorption corporately boosts the catecholase-like activity of DT-Cu.

Synergistically improving the performance of spinel cathode for efficient oxygen reduction electrocatalyst

Optimizing the performance of ceramic fuel cells requires the creation of effective and inexpensive electrocatalysts for the oxygen reduction process. Here, we detail a plan for converting the inert spinel CoAl2O4 into a highly active and superior material for low-temperature ceramic fuel cells through Fe substitution. It turns out that the iron substitution aids in surface reconstruction, increasing oxidation-reduction reaction (ORR) activity. In addition, the reduction in energy bandgap due to Fe doping enhance the Cathode ORR performance, which may be triggered by the ions' kinetics at the surface and interface. The surface layer and Fe doping considerably aid the oxidation-reduction reaction, which creates more oxygen vacancies at the active oxygen site. The prepared materials exhibit enhanced fuel cell performance of 542 mW/cm2 at a temperature of 520 °C. Remarkably, the prepared cathode exhibits a commendable performance of 200 mW/cm2 at a temperature of 420 °C.Furthermore, the CoFe1Al1O4 cell exhibits a decreased Rp (polarization resistance) value of 0.6423 ohm-cm2 at a temperature of 520 °C, demonstrating rapid ORR kinetics. The distribution relaxation time (DRT) shows that the Cathode oxidation-reduction reaction (ORR) activity increased with Fe doping. We present a promising method for improving the oxidation-reduction reaction efficiency of low-temperature ceramic fuel cells.

Fabrication of biocarbon catalyst for ORR by modulating the cellulose fraction of wheat stalk

Direct Methanol fuel cells (DMFC) have been limited in their utilization due to their slow cathodic oxygen reduction reaction (ORR) kinetics and the expensive cost of commercial Pt/C catalysts. It is critical to design an oxygen reduction process with high-efficiency catalysts. An approach for modulating the ratio of cellulose, hemicellulose, and lignin in the wheat stalk (WS)/wheat stalk binder (WS binder) precursor materials is proposed in this work. WS binder from alkalization and hydrothermal treatment was added to the WS to change the structure and shape of WS-based carbon materials by varying the ratios, which increased the ORR catalytic activity. The half-wave potential (E1/2) of the produced carbon material (15 wt% N/C (WS)) is 0.76 V, which was enhanced by 80 mV by adjusting the ratio of the WS/WS binder compared to 0 wt% N/C(WS). The E1/2 of 15 wt% Fe–N/C (WS) (0.85 V) was greater than that of commercial Pt/C (0.84 V). Besides, its catalytic oxygen reduction process was close to the 4-electron transfer pathway and had good methanol tolerance. The power density obtained with a cathode catalyst of 15 wt% Fe–N/C (WS) for DMFC was 1.39 mW cm−2 at 30 °C and 3.33 mW cm−2 at 60 °C. At different temperatures, the power densities were 1.59 and 1.54 times greater than those of commercial Pt/C catalysts, respectively.

Integrative Active Sites of Cathode for Electron-Oxygen-Proton Coupling To Favor H2O2 Production in a Photoelectrochemical System.

The oxygen reduction process generating H2O2 in the photoelectrochemical (PEC) system is milder and environmentally friendly compared with the traditional anthraquinone process but still lacks the efficient electron-oxygen-proton coupling interfaces to improve H2O2 production efficiency. Here, we propose an integrated active site strategy, that is, designing a hydrophobic C-B-N interface to refine the dearth of electron, oxygen, and proton balance. Computational calculation results show a lower energy barrier for H2O2 production due to synergistic and coupling effects of boron sites for O2 adsorption, nitrogen sites for H+ binding, and the carbon structure for electron transfer, demonstrating theoretically the feasibility of the strategy. Furthermore, we construct a hydrophobic boron- and nitrogen-doped carbon black gas diffusion cathode (BN-CB-PTFE) with graphite carbon dots decorated on a BiVO4 photoanode (BVO/g-CDs) for H2O2 production. Remarkably, this approach achieves a record H2O2 production rate (9.24 μmol min-1 cm-2) at the PEC cathode. The BN-CB-PTFE cathode exhibits an outstanding Faraday efficiency for H2O2 production of ∼100%. The newly formed h-BN integrative active site can not only adsorb more O2 but also significantly improve the electron and proton transfer. Unexpectedly, coupling BVO/g-CDs with the BN-CB-PTFE gas diffusion cathode also achieves a record H2O2 production rate (6.60 μmol min-1 cm-2) at the PEC photoanode. This study opens new insight into integrative active sites for electron-O2-proton coupling in a PEC H2O2 production system that may be meaningful for environment and energy applications.

Exploring Advanced Oxygen Reduction Reaction Electrocatalysts: The Potential of Metal-Free and Non-Pyrolyzed Covalent Organic Frameworks.

Oxygen reduction reaction (ORR) electrocatalysis is an area of increasing interest for the in-situ production of H2O2 or the development of energy-related devices such as hydrogen fuel cells. Although pyrolyzed catalysts still offer the best performances to date with reference to the organic-based catalysts, metal-free and non-pyrolyzed covalent organic frameworks (COFs) stands out as promising alternatives candidates due to their favourable characteristics such as crystallinity, porosity, and organic composition, allowing the study of structural-property relationships. Herein, we present the design principles and recent advances in COFs-based ORR electrocatalysts, demonstrating how composition influences the activity and electronic pathway of the oxygen reduction process.

A novel bifunctional particle electrode with abundant Fe/Fe3C and Fe-N-C sites to enhance the performance of electro-Fenton in degrading organic pollutant

Electro-Fenton (EF) technology emerges as a promising approach to address the treatment of persistent organic pollutants. Nevertheless, its practical implementation often comes with certain drawbacks, like the low H2O2 activation efficiency, poor pH adaptability, and difficult recycling of the catalysts. To this end, we introduced highly active Fe-N-C sites onto the surface of nitrogen-doped graphene, improved the chemical environment of its central Fe atoms with Fe/Fe3C nanoparticles, effectively regulated the multi-electron oxygen reduction process of the catalyst in the electrochemical reaction, and realized the efficient production and activation of H2O2 in the electro-Fenton process. The synthesized Fe/Fe3C@FeNG-1000 achieved efficient removal of refractory organic pollutants in neutral conditions. The rate constant of degradation for tetracycline hydrochloride (TC) in the electro-Fenton reaction system at pH 7 was recorded as 0.1011 min−1. Additionally, a removal rate of 67.4% for total organic carbon (TOC) was achieved in just 120 min. The treatment of actual wastewater also showed excellent performance, with an average specific energy consumption of 6.16 kWh kg−1 COD−1. Fe/Fe3C@FeNG-1000 can still achieve more than 90% degradation efficiency after 5 consecutive cycles of the experiment, showing excellent stability, and the catalyst can be conveniently retrieved via magnetic methods following the reaction. The results show that the Fe/Fe3C@FeNG-1000-EF system has a wide range of pH applicability, long-term stability and good recyclability, has a good application value in practical wastewater treatment.

Construction of a Visible-Light-Response Photocatalysis-Self-Fenton Degradation System of Coupling Industrial Waste Red Mud to Resorcinol-Formaldehyde Resin.

Heterogeneous photocatalysis-self-Fenton technology is a sustainable strategy for treating organic pollutants in actual water bodies with high-fluent degradation and high mineralization capacity, overcoming the limitations of the safety risks caused by adding external iron sources and hazardous chemicals in the homogeneous Fenton reaction and injecting high-intensity energy fields in photo-Fenton reaction. Herein, a photo-self-Fenton system based on resorcinol-formaldehyde (RF) resin and red mud (RM) was established to generate hydrogen peroxide (H2O2) in situ and transform into hydroxy radical (•OH) for efficient degradation of tetracycline (TC) under visible light irradiation. The capturing experiments and electron spin resonance (ESR) confirmed that the hinge for the enhanced performance of this system is the superior H2O2 yield (499 μM) through the oxygen reduction process (ORR) of the two-step single-electron over the resin and the high concentration of •OH due to activation effect of RM. In addition, the Fe2+/Fe3+ cycles are accelerated by photoelectrons to effectively initiate the photo-self-Fenton reaction. Finally, the possible degradation pathways were proposed via liquid chromatography-mass spectrometry (LC-MS). This study provides a new idea for environmental recovery in a waste-based heterogeneous photocatalytic self-Fenton system.

Understanding Advanced Transition Metal-Based Two Electron Oxygen Reduction Electrocatalysts from the Perspective of Phase Engineering.

Non-noble transition metal (TM)-based compounds have recently become a focal point of extensive research interest as electrocatalysts for the two electron oxygen reduction (2e- ORR) process. To efficiently drive this reaction, these TM-based electrocatalysts must bear unique physiochemical properties, which are strongly dependent on their phase structures. Consequently, adopting engineering strategies toward the phase structure has emerged as a cutting-edge scientific pursuit, crucial for achieving high activity, selectivity, and stability in the electrocatalytic process. This comprehensive review addresses the intricate field of phase engineering applied to non-noble TM-based compounds for 2e- ORR. First, the connotation of phase engineering and fundamental concepts related to oxygen reduction kinetics and thermodynamics are succinctly elucidated. Subsequently, the focus shifts to a detailed discussion of various phase engineering approaches, including elemental doping, defect creation, heterostructure construction, coordination tuning, crystalline design, and polymorphic transformation to boost or revive the 2e- ORR performance (selectivity, activity, and stability) of TM-based catalysts, accompanied by an insightful exploration of the phase-performance correlation. Finally, the review proposes fresh perspectives on the current challenges and opportunities in this burgeoning field, together with several critical research directions for the future development of non-noble TM-based electrocatalysts.

Fabrication and preliminary testing of patterned silver cathodes for proton conducting IT-SOFCs

Patterned Ag cathodes are fabricated over a proton conducting electrolyte, and the preliminary electrochemical results suggest that the oxygen reduction process over Ag is likely controlled by both oxygen dissociation and charge transfer.

NaCl-templated synthesis of soybean-derived nitrogen-rich mesoporous carbon material: iron phthalocyanine integration for four-electron oxygen reduction

Mesoporous carbon, synthesized from soybean using NaCl as a template, is further integrated with iron phthalocyanine. This combination yields a material (FePc@SN950) with enhanced selectivity for the four-electron oxygen reduction process.

Mechanism and preparation research of binary heteroatom co-doped (X = N, S, P) platinum/carbon black electrocatalysts for an enhanced oxygen reduction reaction via a one-pot pyrolysis method

The picture vividly showcases the oxygen reduction process of single-atom doped and double-atom doped carbon supported platinum electrocatalysts.

Well-organized metal-free chemically reduced graphene oxide sheets as electrocatalysts for enhanced oxygen reduction reactions in alkaline media

Metal-free reduced graphene oxides have recently received attention as potential replacements for platinum-based electrocatalysts. In the present study, we investigated the electrochemical characteristics of chemically reduced graphene oxides (C-rGO) in oxygen reduction reactions (ORR). The C-rGO displays significantly enhanced catalytic activity towards the ORR in alkaline solutions compared to the starting graphene oxide (GO). The thermal properties of C-rGO show good thermal stability, and structural defects in C-rGO were confirmed by Raman analysis. Electrochemical impedance spectroscopy (ESI) analysis confirmed C-rGO superior electron transport capacity over GO. The onset potential (0.82 V), lower Tafel slope, and current density (-5.6 × 10-4 mA/cm2) of the C-rGO catalysts were increased compared to GO due to the majority of functional groups removed after chemical reductions. It's clear that catalysts work through four electron (e-) ORR processes bacause the C-rGO has higher electron transfer numbers (3.8 at a potential of −0.63 V).

In situ study the effects of bias and electric field intensity on electrochemical migration behavior of Sn96.5Ag3.0Cu0.5 solder alloy

In this work, the influence of bias and electric field intensity on the electrochemical migration of SAC305 solder alloy is investigated using a self-designed in-situ thin electrolyte film device. The results indicate that when the bias is 0.5 V, a compact passivation film forms on the sample surface, effectively inhibiting dendrite growth. When the applied bias reaches 0.75 V, it is observed that specific corrosion products are generated between the two plates, and the occurrence of dendritic growth phenomena is still absent. Dendrite development is observed when a bias voltage of 1 V is applied. Regarding the electrode reactions, when the applied bias falls below 1.5 V, a notable polarization resistance is encountered in the anode reaction. In this case, the cathode reaction primarily entails the process of oxygen reduction. As the applied voltage climbs to 1.5 V, the anodic potential shows an increase, leading to a reduction in the polarization resistance of the anodic process that determines the rate of the electrochemical reaction. At this time, the cathode potential exhibits a comparatively negative value, leading to the progressive occurrence of the hydrogen evolution process. Additionally, the influence mechanism of bias on ECM is also proposed.