Activation Of Oxygen Molecules Research Articles

Rational Design of Highly Efficient PdIn–In2O3 Interfaces by a Capture-Alloying Strategy for Benzyl Alcohol Partial Oxidation

Well-dispersed PdIn bimetallic alloy nanoparticles (1-4 nm) were immobilized on mesostructured silica by an in situ capture-alloying strategy, and PdIn-In2O3 interfaces were rationally constructed by changing the In2O3 loading and reduction temperature. The catalytic performance for benzyl alcohol partial oxidation was evaluated, and a catalytic synergy was observed. The Pd-rich PdIn-In2O3 interface is prone to be formed on the catalyst with a low In2O3 loading after being reduced at 300 °C. It was demonstrated that the Pd-rich PdIn-In2O3 interface was more active for benzyl alcohol partial oxidation than In-rich Pd2In3 species, which was likely to be formed at a high reduction temperature (400 °C). The high catalytic activity on the Pd-rich PdIn-In2O3 interface was attributed to the exposure of more Pd-enriched active sites, and an optimized PdIn-In2O3/Pd assemble ratio enhanced the oxygen transfer during partial oxidation. The density functional theory (DFT) calculation confirmed that the Pd-rich Pd3In1(111)-In2O3 interface facilitated the activation of oxygen molecules, resulting in high catalytic activity.

Atomically Dispersed Pt-Doped Co3 O4 Spinel Nanoparticles Embedded in Polyhedron Frames for Robust Propane Oxidation at Low Temperature.

This study adopts a facile and effective in situ encapsulation-oxidation strategy for constructing a coupling catalyst composed of atomically dispersed Pt-doped Co3 O4 spinel nanoparticles (NPs) embedded in polyhedron frames (PFs) for robust propane total oxidation. Benefiting from the abundant oxygen vacancies and more highly valent active Co3+ species caused by the doping of Pt atoms as well as the confinement effect, the optimized 0.2Pt-Co3 O4 NPs/PFs catalyst exhibits excellent propane catalytic activity with low T90 (184 °C), superior apparent reaction rate (21.62×108 (mol gcat -1 s-1 )), low apparent activation energy (Ea = 17.89kJ mol-1 ), high turnover frequency( 811×107 (mol gcat -1 s-1 )) as well as good stability. In situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory calculations indicate that the doping of Pt atoms enhances the oxygen activation ability, and decreases the energy barrier required for CH bond breaking, thus improving the deep oxidation process of the intermediate species. This study opens up new ideas for constructing coupling catalysts from atomic scale with low cost to enhance the activation of oxygen molecules and the deep oxidation of linear short chain alkanes at low temperature.

Atomically Strained Metal Sites for Highly Efficient and Selective Photooxidation.

Strain engineering is an attractive strategy for improving the intrinsic catalytic performance of heterogeneous catalysts. Manipulating strain on the short-range atomic scale to the local structure of the catalytic sites is still challenging. Herein, we successfully achieved atomic strain modulation on ultrathin layered vanadium oxide nanoribbons by an ingenious intercalation chemistry method. When trace sodium cations were introduced between the V2O5 layers (Na+-V2O5), the V-O bonds were stretched by the atomically strained vanadium sites, redistributing the local charges. The Na+-V2O5 demonstrated excellent photooxidation performance, which was approximately 12 and 14 times higher than that of pristine V2O5 and VO2, respectively. Complementary spectroscopy analysis and theoretical calculations confirmed that the atomically strained Na+-V2O5 had a high surficial charge density, improving the activation of oxygen molecules and contributing to the excellent photocatalytic property. This work provides a new approach for the rational design of strain-equipped catalysts for selective photooxidation reactions.

Direct Oxygen‐Oxygen Cleavage through Optimizing Interatomic Distances in Dual Single‐atom Electrocatalysts for Efficient Oxygen Reduction Reaction

AbstractThe oxygen reduction reaction (ORR) on transition single‐atom catalysts (SACs) is sustainable in energy‐conversion devices. However, the atomically controllable fabrication of single‐atom sites and the sluggish kinetics of ORR have remained challenging. Here, we accelerate the kinetics of acid ORR through a direct O−O cleavage pathway through using a bi‐functional ligand‐assisted strategy to pre‐control the distance of hetero‐metal atoms. Concretely, the as‐synthesized Fe−Zn diatomic pairs on carbon substrates exhibited an outstanding ORR performance with the ultrahigh half‐wave potential of 0.86 V vs. RHE in acid electrolyte. Experimental evidence and density functional theory calculations confirmed that the Fe−Zn diatomic pairs with a specific distance range of around 3 Å, which is the key to their ultrahigh activity, average the interaction between hetero‐diatomic active sites and oxygen molecules. This work offers new insight into atomically controllable SACs synthesis and addresses the limitations of the ORR dissociative mechanism.

Direct Oxygen-Oxygen Cleavage through Optimizing Interatomic Distances in Dual Single-atom Electrocatalysts for Efficient Oxygen Reduction Reaction.

The oxygen reduction reaction (ORR) on transition single-atom catalysts (SACs) is sustainable in energy-conversion devices. However, the atomically controllable fabrication of single-atom sites and the sluggish kinetics of ORR have remained challenging. Here, we accelerate the kinetics of acid ORR through a direct O-O cleavage pathway through using a bi-functional ligand-assisted strategy to pre-control the distance of hetero-metal atoms. Concretely, the as-synthesized Fe-Zn diatomic pairs on carbon substrates exhibited an outstanding ORR performance with the ultrahigh half-wave potential of 0.86 V vs. RHE in acid electrolyte. Experimental evidence and density functional theory calculations confirmed that the Fe-Zn diatomic pairs with a specific distance range of around 3 Å, which is the key to their ultrahigh activity, average the interaction between hetero-diatomic active sites and oxygen molecules. This work offers new insight into atomically controllable SACs synthesis and addresses the limitations of the ORR dissociative mechanism.

External oxidant-free remediation of antibiotics: Activation of oxygen molecules to generate hydroxyl radicals using Co-Fe3S4 nanoflowers

To overcome the obstacles of adding oxidants for the decontamination of antibiotics in natural aqueous environment, an external oxidant-free system was developed to in-situ generate reactive oxygen species (ROS) through the activation of dissolved oxygen molecules (O2). Guided by density functional theory (DFT) calculation, cobalt-doped Fe3S4 (Co-Fe3S4) nanoflowers were designed and synthesized, which exhibited superior O2 adsorption and activation ability. Co-Fe3S4 triggered a long-lasting generation of •OH with a high yield of 16.63 μM •OH, which was 3 times higher than that of Fe3S4. Furthermore, use of Co-Fe3S4 resulted in a 7.33-fold improvement in sulfamethoxazole’s degradation rate and boosted the degradation efficiency from 43% to over 90% in the long-run experiments compared to Fe3S4. With 18O2 isotopic investigations, we quantitatively revealed that •OH was generated via O2′s one-step dissociative adsorption process and the directional electron transfer contributed by structural S(-II). Without the addition of external oxidants (e.g., H2O2, O3), we have reported an efficient one-step activation of O2 to generate ROS for effective degradation of antibiotics. Hence, we have provided a new strategy for the control of emerging organics in natural water systems, as well as shed light on the mechanisms of in-situ •OH generation.

Dual defect sites of nitrogen vacancy and cyano group synergistically boost the activation of oxygen molecules for efficient photocatalytic decontamination

Solar-driven photodegradation of pharmaceutical and personal care products (PPCPs) is an attractive strategy for environmental remediation but faces poor activity mainly due to the unsatisfied generation rate of active radicals. Herein, we design and synthesize a hierarchical C3N4 tubes containing dual defect sites of nitrogen vacancy and cyano group (Nv/Cy-tCN) via an alkali-assisted strategy. Density functional theory calculations demonstrate that modification of dual defect sites boost the activation of molecular oxygen through the polarization of O-O bonds. Furthermore, the ability to separate carriers and absorb light can be enhanced by the creation of an electron-rich structure in Nv/Cy-tCN. Consequently, the Nv/Cy-tCN shows excellent photo-degradation performance for eleven types of PPCPs, affording a 100% removal rate toward diclofenac within 7 min of natural sunlight irradiation. The Nv/Cy-tCN system exhibited enhanced diclofenac degradation kinetics with a reaction rate constant of 0.055 min−1, which was 12.8 times higher than that of pristine carbon nitride (0.0043 min−1). Importantly, the impacts on real wastewater and the degradation of trace contaminants further support that this photocatalytic system could be effectively used to remediate PPCPs pollution in environmental waterways.

DTPA-Bound Planar Catechin with Potent Antioxidant Activity Triggered by Fe3+ Coordination

In diseases related to oxidative stress, accumulation of metal ions at the site of pathogenesis results in the generation of reactive oxygen species (ROS) through the reductive activation of oxygen molecules catalyzed by the metal ions. If these metals can be removed and the generated ROS can be strongly scavenged, such diseases can be prevented and treated. Planar catechins exhibit stronger radical scavenging activity than natural catechins and can efficiently scavenge hydroxyl radicals generated by the Fenton reaction without showing pro-oxidant effects, even in the presence of iron ions. Hence, in the current study, we designed a compound in which diethylenetriaminepentaacetic acid (DTPA), a metal chelator, was bound to a planar catechin with enhanced radical scavenging activity by immobilizing the steric structure of a natural catechin to be planar. This compound showed almost no radical scavenging activity due to intramolecular hydrogen bonding of DTPA with the planar catechins; however, when coordinated with Fe3+, it showed more potent radical scavenging activity than planar catechins. Owing to its potent antioxidant activity triggered by metal coordination and its inhibition of ROS generation by trapping metal ions, this compound might exert excellent preventive and therapeutic effects against oxidative stress-related diseases.

Biomimetic catalytic aerobic oxidative desulfurization of diesel with NHPI-based ternary deep eutectic solvents

It is a challenging issue to achieve efficient aerobic oxidation desulfurization (AODS) under mild conditions. Inspired by respiratory chain system, a metal-free biomimetic system was developed in this paper with a functionalized ternary deep eutectic solvent (DES) containing N-hydroxyphthalimide (NHPI), p-toluene sulfonic acid (p-TsOH), and polyethylene glycol (PEG) for deep oxidative desulfurization. It was found that the NHPI/5PEG4000/p-TsOH system exhibited an outstanding desulfurization activity, and the removal of dibenzothiophene (DBT) reached 100% within 5 h at 80 οC. Significantly, it is the first attempt to use a DES as an extraction agent, reaction medium, catalyst, and electron transfer mediator (ETM) simultaneously. Mechanistic studies revealed that NHPI demonstrated a dual function: namely, producing the PINO radical to initiate the reaction, and acting as an ETM in biomimetic systems to promote the activation of oxygen molecules, thereby finely improving the AODS performance of the acidic DESs. These findings regarding the aforementioned biomimetic oxygen activation mechanism of the NHPI-based ternary DES for AODS provide a novel insight into the construction of biomimetic system in the future.

Harvesting the Gas Molecules by Bioinspired Design of 1D/2D Hybrids Toward Sensitive Acetone Detecting

Single‐atom catalysts (SACs) are highly attractive in many surface‐dependent reactions due to their extraordinary reactivity and maximum atomic efficiency. However, in a practical catalytic system, guiding and transferring the reactant molecules to target single‐atom sites are crucial processes for achieving high‐efficient reactions. Herein, gas‐microchannels on TiO2 nanorod‐supported Pt single‐atom catalyst by in situ growing derivative TiO2 nanosheets are constructed. Those perpendicular‐grown TiO2 nanosheets can guide gas molecules to the reactive single Pt sites and thus realize an intact system of guidance‐transfer‐reaction. Experimentally, the local coordination and electronic states of Pt species decrease with the growth of nanosheets, which could significantly strengthen the adsorption and activation of oxygen molecules toward the acetone sensing. The final Pt1/TiO2 catalysts exhibit a high sensing response (13.6–50 ppm) to acetone gas, which are approximately three times higher than that of catalysts without scaly shell (4.8–50 ppm).

Soot oxidation over Pt-loaded CeO2-ZrO2 catalysts under gasoline exhaust conditions: Soot-catalyst contact efficiency and Pt chemical state

Decreasing the ignition temperature of soot combustion is a key of the improved catalyst performances, but a much lower concentration of oxygen from gasoline vehicle exhaust makes the research of the catalyst extremely challenging. Improving the adsorption and activation of oxygen molecules on the catalyst surface and the effective migration rate of active oxygen species are the key factors to enhance soot oxidation. In this work, Pt/CeO2-ZrO2-re catalyst was synthesized by synergistically adjusting CeO2-ZrO2 pore structure and Pt chemical state, as a result, the conversion temperature (T50, 50% soot was oxidized) was reduced by 113 ℃ in 1% O2/N2. The pore structure of CeO2-ZrO2 was optimized by copolymerization microsphere template assisted method, and better soot-contact efficiency and intrinsic properties were obtained, resulting in a higher availability of reactive oxygen species. In addition, adjusting Pt chemical state by using the liquid phase reduction method is significant for the adsorption and activation of oxygen molecules and catalytic cycle of soot oxidation. Structure-activity relationship studies showed that soot oxidation performance is highly related to the initial oxidation state of Pt and pore structure in 1% O2/N2. Better soot-contact efficiency, improved intrinsic properties and the existence of metallic Pt are responsible for the higher soot oxidation activity of Pt/CeO2-ZrO2-re catalyst.

Topological defect and sp3/sp2 carbon interface derived from ZIF-8 with linker vacancies for oxygen reduction reaction

Defects in nanocarbon materials can trigger their intriguing electrochemical properties and potential applications, but their synthesis is challenging. Herein, we report the synthesis of ultrathin nitrogen-doped carbon nanosheets with intrinsic defects through the pyrolysis of ZIF-8 with linker vacancies. The as-synthesized electrocatalyst exhibits excellent oxygen reduction reaction (ORR) activity with an onset potential and half-wave potential of 1.05 and 0.873 V vs. RHE, respectively, outperforming the reported metal-free ORR electrocatalysts. It also shows a commercial Pt/C-comparable performance in zinc–air battery with a power density of 154.4 mW cm−2. Characterization and DFT calculation results suggest the adjacent sp3-carbon in carbon pentagon can significantly strengthen the adsorption and activation of oxygen molecules on sp2-carbon, hence the potential determining step is altered and ORR overpotential is lowered. This work highlights a promising green synthesis strategy of MOF-derived metal-free nanocarbon materials for wide application in advanced energy technologies.

Dual-site oxygen activation for enhanced photocatalytic aerobic oxidation by S-scheme Ni2P/Bi3O4Br-OVs heterojunction

Solar-driven activation of molecular oxygen (O2) offers an appealing strategy to realize aerobic oxidation catalysis at room temperature, while the efficiency of photocatalytic O2 activation is severely limited by lacking O2 adsorption sites and poor carrier utilization. Herein, an efficient Ni2P/Bi3O4Br-OVs heterojunction is firstly proposed to overcome the limitation by the dual-site design of oxygen vacancies (OVs) and on Ni2P cocatalyst. By the joint observations from spectroscopic measurements and theoretical simulations, the introduction of OVs and Ni2P on Bi3O4Br nanosheets can not only optimize the light absorption, facilitate the separation and transfer of photogenerated charge carrier through the S-scheme mechanism, but also provide active sites for effective adsorption and activation of oxygen molecules, thereby contributing to highly efficient generation of •O2− radicals. Benefiting from the more oxidative active species of •O2− and h+, the Ni2P/Bi3O4Br-OVs photocatalyst achieves near-unity conversion rate and selectivity in aerobic oxidation of sulfide to sulfoxide, and it also exhibits outstanding photoactivity in the aerobic degradation of phenolic pollutants under visible light. This study showcases a feasible O2 activation approach by defect and heterojunction engineering, and provides a new perspective for designing high-performance photocatalysts in the field of aerobic oxidation catalysis.

The C-H Bond Activation Triggered by Subsurface Mo Dopant on MgO Catalyst in Oxidative Coupling of Methane

In this work, density functional theory calculations are performed to explore the unique role of Mo dopant on MgO in oxidative coupling of methane. It is revealed that subsurface Mo dopant significantly enhanced the adsorption and activation of oxygen molecules. The combination of adsorbed oxygen and surface Mg exhibited a balanced activity for C-H bond activation and release of methyl radical which paves the way to activate methane with a promising yield.

Microwave-Assisted Photocatalytic Degradation of Organic Pollutants via CNTs/TiO2

Introducing microwave fields into photocatalytic technology is a promising strategy to suppress the recombination of photogenerated charge carriers. Here, a series of microwave-absorbing photocatalysts, xCNTs/TiO2, were prepared by combining titanium dioxide (TiO2) with carbon nanotubes (CNTs) using a typical alcoholic thermal method to study the promotion of microwave-generated thermal and athermal effects on the photocatalytic oxidation process. As good carriers that are capable of absorbing microwaves and conducting electrons, CNTs can form hot spots and defects under the action of the thermal effect from microwaves to capture electrons generated on the surface of TiO2 and enhance the separation efficiency of photogenerated electrons (e−) and holes (h+). Excluding the influence of the reaction temperature, the athermal effect of the microwave field had a polarizing effect on the catalyst, which improved the light absorption rate of the catalyst. Moreover, microwave radiation also promoted the activation of oxygen molecules and hydroxyl groups on the catalyst surface to generate more reactive oxygen radicals. According to the mechanism analysis, the microwave effect significantly improved the photocatalytic advanced oxidation process, which lays a solid theoretical foundation for practical application.

Graphitized and curved carbon nanochambers embedded with highly-dispersed cobalt moieties for oxygen reduction electrocatalysis

Designed synthesis of robust while earth-abundant carbon-based electrocatalysts for oxygen reduction reaction (ORR) is central for the wide spread application of renewable energy conversion technologies. Herein, graphitized and curved carbon nanochambers decorated with boron and nitrogen tailored highly-dispersed cobalt moieties (B,N-Co/GCCN) were developed via a feasible strategy combining room temperature crosslinking and in situ catalytic graphitization processes. The graphitized and curved carbon nanochambers enhanced the electron transfer and structural stability and tailored the electronic structure of metal active sites. Moreover, the in situ coupled amorphous carbon and cobalt-nitrogen/boron moieties represented catalytically active sites for catalyzing ORR. Notably, the selected B doping made the electron density of Co of B,N-Co/GCCN higher compared to N-Co/GCCN, promoting the adsorption and activation of oxygen molecule. Benefiting from this integrated structure, the B,N-Co/GHC exhibited high ORR activity comparable to commercial Pt/C catalyst, along with robust electrocatalytic stability with little change in half-wave potential after 5000 cycles. Impressively, a homemade zinc-air battery driven by B,N-Co/GHC showed higher discharging performance than the one driven by Pt/C, demonstrating promising application prospect.

Coupling Fe3 C Nanoparticles and N-Doping on Wood-Derived Carbon to Construct Reversible Cathode for Zn-Air Batteries.

Electrochemical reduction of oxygen plays a critical role in emerging electrochemical energy technologies. Multiple electron transfer processes, involving adsorption and activation of O2 and generation of protons from water molecules, cause the sluggish kinetics of the oxygen reduction reaction (ORR). Herein, a double-active-site catalyst of Fe3 C nanoparticles coupled to paulownia wood-derived N-doped carbon (Fe3 C@NPW) is fabricated via an active-site-uniting strategy. One site on Fe3 C nanoparticles contributes to activating water molecules, while another site on N-doped carbon is responsible for activating oxygen molecules. Benefiting from the synergistic effect of double active sites, Fe3 C@NPW delivers a remarkable catalytic activity for ORR with a half-wave potential of 0.87V (vs. RHE) in alkaline electrolyte, outperforming commercial Pt/C catalyst. Moreover, zinc-air batteries (ZABs) assembled with Fe3 C@NPW as a catalyst on cathode achieve a large specific capacity of 804.4mA h gZn-1 and a long-term stability of 780 cycles. The model solid-state ZABs also display satisfactory performances with an open-circuit voltage of 1.39V and a high peak power density of 78mW cm-2 . These outstanding performances reach the level of first-rank among the non-noble metal electrode materials. This work offers a promising approach to creating double-active-site catalysts by the active-site-uniting strategy for energy conversion fields.

Recent Progress in Green Conversion of Biomass Alcohol to Chemicals via Aerobic Oxidation

The aerobic oxidation of biomass transformations into valuable chemical products via a green catalytic process is one of the most important protocols because of its low reaction temperature and high productivity rate. Recently, the introduction of small-sized Cu and Au nanoparticles (e.g., 1–3 nm) upon the surface of oxides can provide more catalytic active sites and then enhance the catalytic activity of aerobic oxidations significantly. The introduction of these metal nanoparticles is a kind of perfect catalyst for enhancing the efficiency of the activation of oxygen molecules and the separation of photo-generated holes and electrons during the photo-oxidation reactions. In this account, we summarize recent progress of the aerobic oxidation of biomass alcohol toward the production of highly valuable chemicals over supported catalysts of metal nanoparticles (NPs), including methanol conversion into methyl formate via photo-oxidation over CuOx/TiO2 nanocomposites, biomass ethanol transformation with biomass furfural to produce hydrocarbons biofuels over Au/NiO catalysts, and glucose oxidation to gluconic acid using Au/activated carbon (Au/AC) as catalysts. Furthermore, at the atomic level, to understand the structure-property correlations, insights into molecular activations of oxygen and biomass, and the investigation of active catalytic sites on photo/catalysts will be detailed and discussed. Finally, future studies are needed to achieve more exciting progress in the fundamental revealing of the catalytic reaction mechanisms and conversion pathway and the future perspective in industrial applications.

MOXD1 knockdown suppresses the proliferation and tumor growth of glioblastoma cells via ER stress-inducing apoptosis

Oxygenase-catalyzed reduction and activation of oxygen molecules and the incorporation of oxygen atoms into organic molecules are undoubtedly necessary in the process of tumor development, and it is also one of the research hotspots in recent years. MOXD1 belongs to the copper-dependent monooxygenase family. The expression of MOXD1 is one of the characteristics of early tumor development. However, it is not understandable that the biological function and molecular mechanism of MOXD1 in Glioblastoma (GBM). In this study, high MOXD1 expression is strongly associated with poor survival of the patient with GBM. Moreover. MOXD1 knockdown can inhibit cell viability, proliferation, migration, invasion, and tumorigenesis of GBM cells. This is also proven for the first time that MOXD1 can bind to β3GnT2 and affect the glycosylation modification of some proteins. In addition, knockdown of MOXD1 induces endoplasmic reticulum (ER) stress and triggers the ER–mitochondrial apoptosis pathway. Taken together, these results reveal that MOXD1 is involved in the occurrence and development of GBM, and also provide a new strategy for targeted therapy.

Melatonin and cortisol as components of the cutaneous stress response system in fish: Response to oxidative stress

The skin being a passive biological barrier that defends the organism against harmful external factors is also a site of action of the system responding to stress. It appears that melatonin (Mel) and its biologically active metabolite AFMK (N1-acetyl-N2-formyl-5-methoxykynuramine), both known as effective antioxidants, together with cortisol, set up a local (cutaneous) stress response system (CSRS) of fish, similar to that of mammals. Herein we comment on recent studies on CSRS in fish and show the response of three-spined stickleback skin to oxidative stress induced by potassium dichromate. Our study indicates that exposure of the three-spined stickleback to K2Cr2O7 affects Mel and cortisol levels and pigment dispersion in melanophores in the skin. In our opinion, an increased concentration of Mel and cortisol in the skin may be the strategy to cope with oxidative stress, where both components act locally to prevent damage caused by active oxygen molecules. Furthermore, the pigment dispersion may be a valuable, easy-to-observe mark of oxidative stress, useful in the evaluation of fish welfare.