Oxygen Activation Ability Research Articles

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.

Fabrication of visible light responsive BaFe12O19/Ag/AgI composites with enhanced photocatalytic degradation of organic pollutants

A novel visible-light-driven (VLD) BaFe12O19/Ag/AgI photocatalysts were constructed through calcination and hydrothermal methods, in which BaFe12O19 of different mass ratios were introduced. The constructed Z-scheme heterojunction provided BaFe12O19/Ag/AgI composite catalytic with effective space carrier transport and higher redox ability. In particular, the as-prepared BaFe12O19/Ag/AgI degraded nearly 94 % of 2- mercaptobenzothiazole within 30 minutes of visible-light illumination, which was much superior to that of pure AgI (47 %) and BaFe12O19 (3 %). Moreover, BaFe12O19/Ag/AgI can be easily magnetically separated, so as to facilitate its efficient separation and recovery in practical application. Photocatalytic activity assays revealed that the as-synthesized BaFe12O19/Ag/AgI also exhibited good photodegradation capability towards Imidacloprid, Tetracycline and Carbamazepine. In particular, the complex had relatively high oxygen activation ability, and its photocatalytic H2O2 production performance was 1.29 times higher than that of the AgI monomer within 120 minutes, thus realizing rapid water disinfection. Overall, the constructed efficient Z-scheme BaFe12O19/Ag/AgI photocatalysts provide a novel insight in sewage purification.

Enhancing Oxygen Activation Ability by Composite Interface Construction over a 2D Co3O4-Based Monolithic Catalyst for Toluene Oxidation.

Developing robust metal-based monolithic catalysts with efficient oxygen activation capacity is crucial for thermal catalytic treatment of volatile organic compound (VOC) pollution. Two-dimensional (2D) metal oxides are alternative thermal catalysts, but their traditional loading strategies on carriers still face challenges in practical applications. Herein, we propose a novel in situ molten salt-loading strategy that synchronously enables the construction of 2D Co3O4 and its growth on Fe foam for the first time to yield a unique monolithic catalyst named Co3O4/Fe-S. Compared to the Co3O4 nanocube-loaded Fe foam, Co3O4/Fe-S exhibits a significantly improved catalytic performance with a temperature reduction of 44 °C at 90% toluene conversion. Aberration-corrected scanning transmission electron microscopy and theoretical calculation suggest that Co3O4/Fe-S possesses abundant 2D Co3O4/Fe3O4 composite interfaces, which promote the construction of active sites (oxygen vacancy and Co3+) to boost oxygen activation and toluene chemisorption, thereby accelerating the transformation of reaction intermediates through Langmuir-Hinshelwood (L-H) and Mars-van Krevelen (MvK) mechanisms. Moreover, the growth mechanism reveals that 2D Co3O4/Fe3O4 composite interfaces are generated in situ in molten salt, inducing the growth of 2D Co3O4 onto the surface lattice of 2D Fe3O4. This study provides new insights into enhancing oxygen activation and opens an unprecedented avenue in preparing efficient monolithic catalysts for VOC oxidation.

Atomic Co/Cu Dual‐Metal for Rapid Conversion of 5‐Hydroxymethylfurfural under Ambient Pressure

AbstractAtomic scaling of cobalt‐based catalysts is the feasible and sustainable approach for selective oxidation of biomass‐derived 5‐hydroxymethylfurfural (HMF) to produce bio‐plastic monomer of 2,5‐furandicarboxylic acid (FDCA) under mild conditions. Here, a high‐efficiency dual single‐atomic Co/Cu supported on nitrogen‐doped carbon (a‐Co/Cu‐NC) is constructed. Leveraging exceptional oxygen activation ability, the Co/Cu dual‐atomic‐sites can accelerate the HMF oxidation, suppressing by‐product formation mediated by reactive oxygen species (ROS) in low‐oxygen environments. This leads to enhanced FDCA selectivity with a yield of 98% and a production rate of 298.8 mmolFDCA gmetal−1 h−1 under ambient conditions. Comprehensive experiments and density functional theory (DFT) calculations demonstrate that long‐range interactions between Co and Cu sites optimize reactant adsorption and lower energy barriers for •O2− and HMFCA formation.

An investigation on a WO3/MoO3−x heterojunction photocatalyst for excellent photocatalytic performance and enhanced molecular oxygen activation ability

A novel Z-scheme WO3/MoO3−x heterojunction was synthesized through hydrothermal method. The heterojunction with unique localized surface plasmon resonance (LSPR) effects had excellent photocatalytic performance.

Constructing a novel super-crosslinked triazine COF through molecular expansion for enhanced photocatalytic performance under visible light

A novel hypercrosslinked triazine COF photocatalyst (HCTF-2) with excellent photocatalytic performance was constructed by molecular expansion. HCTF-2 has a larger specific surface area and exhibits excellent molecular oxygen activation ability.

Insights into the differences in metal anchoring mechanisms and the impact on HCN catalytic oxidation performance

Hydrogen cyanide (HCN) is often produced in various industrial processes, such as metal smelting, carbon fiber production, etc. Due to its highly toxic nature, it has significant harm to the human body and the environment. Catalytic oxidation can convert HCN into non-toxic N2, CO2 and H2O. In this study, we conducted a comparative evaluation of the catalytic oxidation of HCN using Cu, Co and Mn as catalyst active centers, and used in situ DRIFTS to explore the reaction mechanism of HCN catalytic oxidation. The difference in the anchoring state of different metals on the hydroxyl groups on the Al2O3 surface, mainly the difference in anchoring strength and hydroxyl consumption, determines the difference in the metal dispersion state, which in turn affects the oxygen activation ability and HCN oxidation performance. Under high loading conditions, compared to Co and Mn, Cu species are more fully anchored due to lower hydroxyl consumption, exhibiting higher dispersion and redox properties, so the 10Cu/Al2O3 catalyst performs well HCN oxidation activity.

The role of oxide supports in constructing plasma-treated gold nanocatalysts for visible light photocatalytic oxidation of CO

Supported Au nanocatalysts are highly attractive plasmonic nanostructures for visible light (VL) photocatalysis due to their significant promise in direct conversion of solar to chemical energy. A promising strategy to prepare high-performance supported plasmonic Au nanocatalysts is treating the catalysts with plasma, where the support holds the key to constructing active Au-support interfaces by interacting with Au nanoparticles. Herein the role of oxide supports in constructing plasma-treated plasmonic Au nanocatalysts for VL photocatalytic oxidation of CO is studied by comparing effect of plasma treatment on typical oxides of TiO2, CeO2 and Al2O3 supported Au nanocatalysts. After O2 plasma treatment, CeO2 supported Au nanocatalyst obtains the highest intrinsic catalytic activity due to its high dispersion of Au nanoparticles induced by strong interaction between CeO2 and Au and strong oxygen activation ability. The O2 plasma treatment enables TiO2 supported Au nanocatalyst to exhibit the largest enhancement in catalytic activity under VL irradiation, which originates from the favorable hot-electron transfer process. This process is not only attributed to the strong surface plasmon resonance of Au nanoparticles and large numbers of Au-TiO2 interfacial sites that result from moderate interaction between TiO2 and Au, but also depends on the low Schottky barrier height at Au-TiO2 interface due to the small work function difference between TiO2 and metallic Au. This investigation deepens the understanding of the role of oxide supports in constructing plasma-treated supported Au nanocatalysts, and can be instructive for the design and optimization of plasmonic Au nanocatalysts for VL photocatalytic reactions.

Defect-Confinement Strategy for Constructing CuO Clusters on Carbon Nanotubes for Catalytic Oxidation of AsH3 at Room Temperature.

The efficient removal of the highly toxic arsine gas (AsH3) from industrial tail gases under mild conditions remains a formidable challenge. In this study, we utilized the confinement effect of defective carbon nanotubes to fabricate a CuO cluster catalyst (CuO/ACNT), which exhibited a capacity much higher than that of CuO supported on pristine multiwalled carbon nanotubes (MWCNT) (CuO/PCNT) for catalytically oxidizing AsH3 under ambient conditions. The experimental and theoretical results show that nitric acid steam treatment could induce MWCNT surface structural defects, which facilitated more stable anchoring of CuO and then improved the oxygen activation ability, therefore leading to excellent catalytic performance. Density functional theory (DFT) calculations revealed that the catalytic oxidation of AsH3 proceeded through stepwise dehydrogenation and subsequent recombination with oxygen to form As2O3 as the final product.

Highly Active Nanocomposite Air Electrode with Fast Proton Diffusion Channels via Er Doping‐Induced Phase Separation for Reversible Proton Ceramic Electrochemical Cells

AbstractHighly active and durable air electrodes are crucial for the commercialization of reversible proton ceramic electrochemical cells (R‐PCECs) for large‐scale energy conversion and storage that may be developed by introducing oxygen ion, electron, and proton triple conducting species into the electrode materials. Here, a new triple conducting nanocomposite is reported as a promising air electrode of R‐PCECs, which consists of a dominated cubic perovskite Ba0.5Sr0.5Co0.72Fe0.18Er0.09O3‐δ and a minor Er2O3 phase, developed by Er doping induced phase separation of Ba0.5Sr0.5(Co0.8Fe0.2)0.9Er0.1O3‐δ precursor. The Er doping stimulates the primary perovskite phase to possess excellent hydration capability and oxygen activation ability, while the Er2O3 minor phase, as a high‐speed proton transport channel, further cooperates with the perovskite main phase to boost the kinetic rate of the electrode for both oxygen reduction and evolution reactions (ORR/OER). As a result, the corresponding R‐PCEC achieves extraordinary electrochemical performance in fuel cell (1.327 W cm−2 at 650 °C) and electrolysis modes (−2.227 A cm−2 at 1.3 V and 650 °C), which exceed the similar cell with a typical Ba0.5Sr0.5Co0.8Fe0.2O3‐δ single‐phase perovskite air electrode by 82.3% and 122.7%, respectively. This Er‐doping induced phase separation provides a new way for new bifunctional electrodes development.

Magnetically recyclable high-entropy metal oxide catalyst for aerobic catalytic oxidative desulfurization

High-entropy metal oxide catalysts have demonstrated exceptional performance in activating oxygen for catalytic oxidation reactions. However, ensuring their ease of cyclic usage is crucial to broadening their applications. To address this challenge, a magnetic and recyclable high-entropy metal oxide catalyst is designed and its potential in catalytic oxidative desulfurization of fuel oils with oxygen as the oxidant is also investigated. Through a mechanochemical-assisted calcination method, the magnetic high-entropy metal oxide catalyst (HEMO-900) is successfully synthesized, and the structure of the HEMO-900 catalyst is comprehensively characterized. In addition, it is found that the high-entropy structure facilitates charge modulation of the active components, thereby enhancing the oxygen activation performance. The HEMO-900 catalyst exhibits exceptional oxygen activation ability and catalytic oxidative desulfurization performance, and 96.9% of sulfur removal is achieved under optimal conditions. In addition, it achieves profound desulfurization of various fuel samples by efficiently oxidizing and eliminating diverse aromatic sulfur compounds. Additionally, the catalyst demonstrates outstanding magnetically recyclable properties, enabling rapid separation and recovery from the fuel oil phase through the application of an external magnetic field, making the HEMO-900 catalyst maintained a remarkable sulfur removal efficiency of 91.1% even in the 5th cycle. Therefore, this magnetically recyclable HEMO-900 catalyst possesses significantly promising research and application prospects in the field of catalytic oxidative desulfurization of fuel oils with oxygen as the oxidant, as well as some other heterogeneous catalysis.

Highly efficient MnOx catalysts derived from Mn-MOFs for chlorobenzene oxidation: The influence of MOFs precursors, oxidant and doping of Ce metal

In this research, we introduce a simple, effective, and eco-friendly approach for preparing MnOx materials with a hierarchical porous structure and apply it to the catalytic oxidation of chlorobenzene. In this method, different Mn-based MOFs are used as templates, and MnOx materials with various morphologies and structures are prepared through an alkaline hydrolysis-oxidation method. Different Mn-MOF precursors, oxidants and doping of different metals have a considerable influence on the structural morphology of the obtained MnOx materials. Through adjusting the structural morphology, it is conducive to transfer, diffusion and enrichment of chlorobenzene during the reaction process, and improving the reaction activity. MnO2-74 catalyst derived from Mn-MOF-74 in the presence of H2O2 showed the best catalytic activity (T90 = 174 °C). The exceptional catalytic efficiency is attributed to its large specific surface area, mesoporous structure, better low-temperature reducibility, sufficient acidic sites, and enhanced oxygen activation ability. The primary cause of the decrease in catalytic activity is the existence of surface carbon and inorganic chlorine on the catalyst. This green, efficient, and economical preparation method introduces a novel strategy for the traditional derivatization of MOFs to prepare metal oxide materials for the catalytic oxidation of chlorinated volatile organic compounds (CVOCs).

Enhanced degradation of micropollutants by visible light photocatalysts with strong oxygen activation ability

Visible light photocatalysis is widely considered a sustainable approach to break down micropollutants without chemical addition. To promote the output of photogenerated carriers under visible light, a Z-scheme plasmonic photocatalyst Bi-CeO2/Ag0/BiO2 was designed and fabricated to activate dissolved oxygen in water for micropollutant degradation. The doped Bi not only improved the separation of electron-hole, but also narrowed the band gap of CeO2 to enhance its absorption of visible light. Notably, metallic silver (Ag0) works as an electronic transmission vehicle from Bi-CeO2 to BiO2 in a Z-scheme mechanism. Likewise, the surface plasmon resonance effect of Ag0 also enhanced the absorption of visible light. Furthermore, the Bi doping induced abundant surface oxygen vacancies on CeO2 for enhanced capability and selectivity towards O2 adsorption and activation, which favored the generation of O2•− by photogenerated electrons to degrade sulfamethoxazole, enrofloxacin, and bisphenol A. Theoretical calculation results also confirmed the O2•−-driven degradation pathway for sulfamethoxazole. Therefore, the Z-scheme Bi-CeO2/Ag0/BiO2 not only extends the photocatalytic reactivity of CeO2-based catalysts to the visible light range, but also provides a chemical-free method to effectively degrade micropollutants.

Efficient propane mineralization over unsaturated Pd cluster/CeO2 with prominent C-C cleavage capacity driven by inherent oxygen activation ability

Light alkanes extensively presented in industrial exhausts have led tremendous harm to the atmospheric environment and human health. However, the catalytic destruction of light alkanes generally operates at elevated temperatures and the consequent reaction by-products are inevitably produced. It is therefore of great significance to engineer catalysts with superior thermal stability, internal activity and selectivity. Herein, we developed a Pd cluster/CeO2 catalyst (Pdn/CeO2) by a scalable deposition precipitation strategy, which demonstrates unexpected activity and thermal stability in the presence of 5% H2O attributing to abundant unsaturated Pd metal sites and excellent oxygen dissociation performance. Pdn/CeO2 possesses a highly efficient C-C cleavage capability due to the persistent formation of a large number of oxygen vacancies. In comparison, the Pd1/CeO2 catalyst, which is preferential for C-H bond cleavage and inactive for C-C bond cracking, produces remarkable hazardous organic by-products such as propyne and propylene, inhibiting the continuous decomposition of propane. The present study sheds critical insights into engineering efficient and stable catalysts for light alkane destruction.

Cyano-Rich g-C3 N4 in Photochemistry: Design, Applications, and Prospects.

Cyano-rich g-C3 N4 materials are widely used in various fields of photochemistry due to the very powerful electron-absorbing ability and electron storage function of cyano, as well as its advantages in improving light absorption, adjusting the energy band structure, increasing the polarization rate and electron density in the structure, active site concentration, and promoting oxygen activation ability. Notwithstanding, there is yet a huge knowledge break in the design, preparation, detection, application, and prospect of cyano-rich g-C3 N4 . Accordingly, an overall review is arranged to substantially comprehend the research progress and position of cyano-rich g-C3 N4 materials. An overall overview of the current research position in the synthesis, characterization (determination of their location and quantity), application, and reaction mechanism analysis of cyano-rich g-C3 N4 materials to provide a quantity of novel suggestions for cyano-modified carbon nitride materials' construction is provided. In view of the prevailing challenges and outlooks of cyano-rich g-C3 N4 materials, this paper will purify the growth direction of cyano-rich g-C3 N4 , to achieve a more in-depth exploration and broaden the applications of cyano-rich g-C3 N4 .

Sintering resistance of Pt-based oxidation catalyst via constructing Pt/MnOx interface

It is a challenge to improve the catalytic activity and hydrothermal stability of platinum-based catalyst in concurrently oxidizing CO/C3H6/NO. The construction of Pt/MnOx interface over Pt-based diesel oxidation catalyst via overlayer deposition to form partial-embedded structure, inhibiting the aggregation of platinum nanoparticles in Ostwald Ripening process. Even after hydrothermal aging, the average platinum particle size is equal to that of the fresh catalyst via traditional impregnation method. The electronic-transferring from platinum to manganese results in a weaker CO adsorption ability on Pt species and an improved oxygen activation ability with the help of the redox cycle of Pt and MnOx, as well as the formation of more active nitrate species via in situ DRIFTs. Measurement on the activity shows the lower apparent activation energy, so that the light-off temperature of CO/C3H6/NO on the partial-embedded catalyst via overlayer deposition method decreases by around 20 °C and 40% NO maximum conversion still keeps after severely aging comparing with the traditional catalyst. The work enlightens us the importance of interface sites in stabilizing platinum atoms and creating oxidize active sites.

High activity of CuO/#-Fe2O3 for low temperature CO oxidation: Effect of support crystal types in catalyst design

A series of Fe2O3 supported CuO catalysts were synthesized to investigate the effect of crystal types on CO oxidation performance of CuO/Fe2O3. The catalysts were characterized with BET surface area, XRD, Raman, O2-TPD, H2-TPR, XPS and in situ DRIFTS. The results showed that the crystal types had significant impact on the performance of CuO/Fe2O3, and the CuO/γ-Fe2O3 catalyst exhibited higher catalytic activity, which corresponding to 98.5% CO conversion at 180 °C. Besides, CuO/γ-Fe2O3 displayed better reducibility, which improved the redox cycle between Fe2+ and Fe3+ species. Furthermore, the pathway of CO oxidation on CuO/Fe2O3 followed L-H mechanism. Large amount of Fe2+ species and oxygen vacancies on CuO/γ-Fe2O3 increased the oxygen activation ability, which provided more reactive oxygen species to promote the rate-determining step in CO oxidation. Moreover, carbonate species on CuO/α-Fe2O3 were prone to accumulate, which resulted in the covering of active sites on catalyst surface and inhibited the adsorption and activation of CO and O2.

Boosting catalytic activity of Cu-Ce solid solution catalysts by flame spray pyrolysis with high Cu+ concentration and oxygen vacancies

Cu-Ce solid solution catalysts are remarkable in catalytic oxidation. However, the traditional synthesis methods struggle to prevent severe phase separation at high Cu concentration. In this study, a stable Cu-Ce solid solution with a Cu content>30% was synthesized by flame spray pyrolysis (FSP). Flame synthesis process with a high reaction temperature of 2000 K and rapid cooling characteristics of over 100 K cm−1 resulted in the enrichment of Cu elements on the catalyst's surface as Cu+. The high Cu content fostered abundant surface oxygen vacancies on the catalyst. The catalyst surface has more CO activation sites due to the high Cu+ concentration, and the abundant oxygen vacancies bring greater oxygen activation ability to the catalyst. It was found that Cu-30 had a reaction rate of 0.48 μmolCO g−1 s−1 at 60 °C, dozens of times higher than other catalysts, and achieved complete conversion of CO at 120 °C. The mechanism suggests that the active site of CO is the surface Cu+, and the oxygen vacancies provide active oxygen species, which facilitate the CO catalytic reaction's rapid progress.

Redox-Induced In Situ Growth of MnO2 with Rich Oxygen Vacancies over Monolithic Copper Foam for Boosting Toluene Combustion.

Catalytic combustion has been known to be an effective technique in volatile organic compound (VOC) abatement. Developing monolithic catalysts with high activity at low temperatures is vital yet challenging in industrial applications. Herein, monolithic MnO2-Ov/CF catalysts were fabricated via the in situ growth of K2CuFe(CN)6 (CuFePBA, a family of metal-organic frames) over copper foam (CF) followed by a redox-etching route. The as-synthesized monolith MnO2-Ov-0.04/CF catalyst displays a superior low-temperature activity (T90% = 215 °C) and robust durability for toluene elimination even in the presence of 5 vol % water. Experimental results reveal that the CuFePBA template not only guides the in situ growth of δ-MnO2 with high loading over CF but also acts as a source of dopant to create more oxygen vacancies and weaken the strength of the Mn-O bond, which considerably improves the oxygen activation ability of δ-MnO2 and consequently boosts the low-temperature catalytic activity of the monolith MnO2-Ov-0.04/CF toward toluene oxidation. In addition, the reaction intermediate and proposed mechanism in the MnO2-Ov-0.04/CF mediated catalytic oxidation process were investigated. This study provides new insights into the development of highly active monolithic catalysts for the low-temperature oxidation of VOCs.

A Stable Triphenylamine-Based Zn(II)-MOF for Photocatalytic H2 Evolution and Photooxidative Carbon–Carbon Coupling Reaction

Efficient charge transfer has always been a challenge in heterogeneous MOF-based photoredox catalysis due to the poor electrical conductivity of the MOF photocatalyst, the toilless electron-hole recombination, and the uncontrollable host-guest interactions. Herein, a propeller-like tris(3'-carboxybiphenyl)amine (H3TCBA) ligand was synthesized to fabricate a 3D Zn3O cluster-based Zn(II)-MOF photocatalyst, Zn3(TCBA)2(μ3-H2O)H2O (Zn-TCBA), which was applied to efficient photoreductive H2 evolution and photooxidative aerobic cross-dehydrogenation coupling reactions of N-aryl-tetrahydroisoquinolines and nitromethane. In Zn-TCBA, the ingenious introduction of the meta-position benzene carboxylates on the triphenylamine motif not only promotes Zn-TCBA to exhibit a broad visible-light absorption with a maximum absorption edge of 480 nm but also causes special phenyl plane twists with dihedral angles of 27.8-45.8° through the coordination to Zn nodes. The semiconductor-like Zn clusters and the twisted TCBA3- antenna with multidimensional π interaction sites facilitate photoinduced electron transfer to render Zn-TCBA a good photocatalytic H2 evolution efficiency of 27.104 mmol·g-1·h-1 in the presence of [Co(bpy)3]Cl2 under visible-light illumination, surpassing many non-noble-metal MOF systems. Moreover, the positive enough excited-state potential of 2.03 V and the semiconductor-like characteristics of Zn-TCBA endow Zn-TCBA with double oxygen activation ability for photocatalytic oxidation of N-aryl-tetrahydroisoquinoline substrates with a yield up to 98.7% over 6 h. The durability of Zn-TCBA and the possible catalytic mechanisms were also investigated by a series of experiments including PXRD, IR, EPR, and fluorescence analyses.