Applied Catalysis B: Environmental最新文献

In order to respond to the call for low emissions and low energy consumption, photoelectrochemical (PEC) ammonia synthesis is used to replace the Haber-Bosch method of nitrogen reduction, and highly efficient photoelectrocatalysts were used to reduce the reaction energy barrier. In this paper, the interlayer MgO and base BiVO₄ were successfully compounded by a simple electrodeposition method, and the spinel MCo₂O₄ (M=Zn, Mn) was compounded on MgO/BiVO₄ by a hydrothermal method, forming a sandwich structure of MCo₂O₄/MgO/BiVO₄ (M=Zn, Mn). The research shows that the sandwich structure constructed by MgO as the intermediate layer can reduce the excessive surface defects of photocatalyst, effectively reduce the recombination of photogenerated charge, promote the directional migration and separation of photogenerated charge, and improve the photocurrent density and photoelectric conversion efficiency. MCo₂O₄ (M=Zn, Mn) is a nitrogen reduction cocatalyst, which forms a heterojunction with n-type BiVO₄ and inhibits the recombination of photogenerated electrons. The synergistic effect of MCo₂O₄(M=Zn, Mn) and MgO accelerates the surface charge transfer efficiency and enhances the photoelectricity ammonia synthesis efficiency. The PEC ammonia synthesis efficiency reached more than 30 µmol h⁻¹ g⁻¹_cat, and the Faradaic efficiency(FE) is over 30%.

The integral part of covalent organic frameworks (COFs) is covalent bonds. Thus, stable and functional links must be developed to expand the potential applications of COFs. Herein, in situ linkage functionalization using a three-component irreversible Doebner reaction was achieved to fabricate chemically stable carboxylic acid-bearing COFs (Tp-Tta-COOH and Tp-Tapb-COOH), which have abundant chelating groups and ordered electron donor–acceptor moieties facilitating charge separation for effective Cr(VI) adsorption and photoreduction, respectively. These functionalized COFs are more effective at Cr(VI) removal via adsorption and photoreduction than their unfunctionalized counterparts (Tp-Tta and Tp-Tapb). The synergy of adsorption and photocatalysis is crucial to effectively remove Cr(VI) from aqueous solutions. This synergy empowers Tp-Tta-COOH to be used continuously for Cr(VI) removal without any elution after each cycle. Furthermore, Tp-Tta-COOH exhibits high chemical stability, durability, and recyclability. This study will promote the development of durable and useful COF materials for real-world applications.

The correlation between the physico-chemical properties of bare and Mo-doped nickel aluminate derived catalysts and product distribution during hydrogenolysis of glycerol with in situ produced hydrogen in continuous was investigated. Stoichiometric nickel aluminate spinel was synthesized via citrate sol-gel in a one-pot synthesis and subsequently doped it with 1 wt% Mo, using both sol-gel one-pot and impregnation methods. Catalytic runs were performed at 235 ºC/ 45 bar for 4 h TOS. The results indicate that Mo-doping increased the number of both metal and acid sites, leading to more selectivity towards deoxygenated products. 1,2-propylene glycol was the major liquid product, Mo/NiAl catalyst exhibited the highest yield (27%) and selectivity (39%). Post-reaction characterization revealed that leaching and oxidation of metals could potentially cause catalyst deactivation. 1 wt% Mo-doped nickel aluminate-derived catalysts possess potential for the selective production of 1,2-PG in a eco-friendly process through one-pot coupling H₂ generation and hydrogenolysis reactions.

Z-scheme heterojunction photocatalysts generally have excellent redox ability and robust removal efficiency for contaminants in water. Herein, we combined p-type PPy and n-type NH₂-UiO-66 by ball milling to prepare a direct Z-scheme PPy/NH₂-UiO-66 photocatalyst with ultra-high redox potential. Notably, the optimized efficiency of PPy/NH₂-UiO-66 (the mass ratio of PPy to NH₂-UiO-66 is 1 wt%, named PPy/NU-1) rapidly reduced Cr(VI) (>95%, 60 min) and TC degradation (>90%, 180 min) at 100 W LED light. Moreover, the PPy/NU-1 has high stability and good anti-interference ability, which can effectively remove Cr(VI) from industrial electroplating wastewater, and the Cr(VI) removal rate is 99%, which meets the industrial wastewater standard and has the potential attraction of actual wastewater treatment. In addition, the techniques of UV-Vis diffuse reflection, electron spin resonance (ESR), photoluminescence (PL), and photoelectrochemical measurement showed that PPy/NH₂-UiO-66 composites improved the light capture ability, thereby improving the photocatalytic efficiency. The PPy/NU-1 has a very high redox potential by constructing a Z-scheme heterojunction, enhances the interfacial charge transfer ability, and improves the separation efficiency of photogenerated carriers. Finally, the mechanism of the Z-scheme was systematically by nitroblue tetrazolium (NBT) and p-phthalic acid (TA) transformation, ESR experiments, and density functional theory (DFT) calculations. This work provides a strategy for the preparation of visible photocatalysts with excellent photocatalytic activity and provides new insights for interfacial charge transfer and molecular oxygen activation.

Perovskite oxides show great promise in the field of water electrolysis due to their low cost and tailorable properties. However, their performance is seriously constrained by crystal agglomeration. Herein, a high-entropy strategy is reported to regulate the lattice strain field, endowing the crystal with a high energy barrier and optimizing its surface properties to achieve conformal growth of highly reactive perovskite oxides. A range of characterization methods and theoretical calculations are used to investigate the lattice distortion-induced complex lattice strain field and the effective activation strategy of the cocktail effect. Based on this, the produced rod-like La(CoFeNiCrAl)O₃ (La5B–Al) exhibits a low overpotential of 285 mV at 10 mA cm⁻² in 1 M KOH. This work provides a novel strategy to use the lattice strain field for regulating the growth of catalysts and clarifies the relationship between high-entropy effects and material properties.

Sulfidated zero-valent iron (SZVI) has been widely used in controlling organic pollutants. However, the significant decrease in catalytic activity of SZVI-based Fenton-like systems under neutral and alkaline conditions remains a large problem. Herein, it was found that surface structure regulation of SZVI with H₂O₂ (HT-SZVI) greatly enhanced its reactivity and efficiently activated H₂O₂ to oxidize various organics in a wide pH range. The HT-SZVI/H₂O₂ system exhibited a pH self-regulation capability that stabilized the eventual solution pH at ∼3.5 at the initial pH of 3.0–9.0. The excellent oxidation performance was primarily attributed to surface-bound ^•OH produced from H₂O₂ activation by surface Fe(II) sites on HT-SZVI. Additionally, dissolved Fe(II) converted from surface Fe(II) induced proton generation to self-regulate pH. Newly formed high proton-conductive FeS and Fe₃O₄ shells accelerated the transfer of accumulated protons in solution to iron core to produce Fe(II), enabling efficient proton consumption-regeneration cycle and enhancing ^•OH production.

A synthetic exhaust gas bench was dynamically operated to investigate the impact of temperature, amplitude, split cycle, mean lambda, gas hourly space velocity, and oxygen storage capacity on average pollutant conversion and product selectivity of three-way catalysts in periodic operation. As temperature and amplitude increase and oxygen storage capacity decreases, the optimal frequency for maximum pollutant conversion increases. This is consistent with faster desorption of CO and O₂ from the catalyst, yielding free surface sites. Regarding the formation of secondary products, the optimal frequency for maximum pollutant conversion does not always correspond to minimal N₂O and NH₃ emissions. The split cycle variation reveals the enhancement of C₃H₈ and NO conversion after both lean-rich and rich-lean switches and C₃H₆ and CO conversion after rich-lean switches at the optimal frequency. As periodic operation does not affect existing engine settings or operating conditions, it is a cost-effective control strategy for meeting future emission limits.

Covalent organic frameworks (COFs) can be precisely modulated through the covalent linkage of organic building blocks. Therefore, developing COFs to high-performance photocatalysts is highly applicable. Herein, with trifluoroacetic acid as the catalyst, Py-Azine-COF is constructed by aldimine condensation between 1,3,6,8-tetrakis(4-formylphenyl)pyrene and hydrazine hydrate. The highly crystalline Py-Azine-COF possesses a remarkable specific surface area of 1428 m² g⁻¹. Intriguingly, selective aerobic conversion is achieved over Py-Azine-COF photocatalyst with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). Significantly, TEMPO accelerates the hole transfer and cooperates with superoxide formed from oxygen for selective oxidation of organic sulfides. With the assistance of 2 mol% TEMPO, the performance of Py-Azine-COF photocatalyst is increased markedly. Gratifyingly, TEMPO, a hole mediator, enables expeditious conversions of various sulfides into sulfoxides over Py-Azine-COF photocatalyst in methanol. Generally, COFs can be customized by modulating the covalent connection of organic building blocks to meet the requirements of selective aerobic oxidations.

Ru-modified monolayer-dispersed WO_x/CeO₂ hybrid composites were prepared by co-impregnation (CI) and step impregnation (SI) methods, and the effects of active site distribution on the catalytic oxidation of 1,2-dichloroethane (DCE) were investigated. Ru species tends to be deposited on the monolayer-dispersed WO_x (m-WO_x) by SI method, which can increase the oxygen vacancies (O_V,m-WOx) at m-WO_x/CeO₂ interfaces. Abundant O_V,m-WOx can promote the formation of more active W–OH and accelerate the dechloridation and oxydehydrogenation of DCE. Oppositely, for CI method, Ru species exists mainly in the form of Ru−O−Ce bonds, increasing the oxygen vacancies (O_V,RuCe) into CeO₂ surface lattices and promoting the deep oxidation of intermediate products. The closer contact between the two hetero-interfacial oxygen vacancies (O_V,RuCe and O_V,m-WOx) on Ru-modified m-WO_x/CeO₂ produces a stronger synergistic effect on DCE activation and oxidation, and meanwhile advantageously inhibits the adsorption of chlorine species as well as the formation of polychlorinated by-products.

Electroreduction of CO₂ to C₂H₄ is a promising strategy for carbon neutralization. However, the kinetic challenge of *CO dimerization, particularly at high current-density, limits its suitability for industrial production. Here, we report that Cu/Ag bimetallic catalyst (Cu₅₂Ag₄₈) with strong interfacial effect can promote high C₂H₄ selectivity at high current-density. We find that the elaborately designed Cu/Ag interface not only inhibits HER and ethanol formation by weakening H adsorption, but also promotes the formation of *CHO intermediates, achieving an unusual asymmetric *CO-*CHO coupling instead of the common symmertic *CO-*CO coupling. Subsequently, the Faradaic efficiency of C₂H₄ over Cu₅₂Ag₄₈ is significantly increased to 69.2% at a high current-density of up to 450 mA cm⁻². The interfacial effect-induced *CO-*CHO coupling can be extended to other metals with weak H and O adsorption such as Cu/Zn and Cu/Au, thereby boosting the production of C₂H₄ in CO₂RR.