Applied Catalysis B: Environmental最新文献

The catalytic oxidation of different volatile organic compounds (VOCs) has been widely studied for several decades within the field of air depollution. However, there is still much to understand regarding the effects that these VOCs have on each other when they are blended together in the reaction mixture, as would be expected in many emissions. Herein, the catalytic oxidation of toluene and 2-propanol on supported manganese oxides under both single and binary VOCs oxidation conditions has been studied. We have found the catalyst activity for VOCs mineralization and its selectivity towards other by-products (i.e., acetone or propylene from 2-propanol) to be strongly dependent on the reaction conditions, the catalyst redox properties and support acidity. We have also assessed the promotion/inhibition effects derived from the VOCs mixture and proposed the reaction mechanism in each case by means of in-situ DRIFTS measurements.

Metal ion doping is an extensively researched method to enhance photocatalytic activity of bismuth-based semiconductors, but function of the metal ions need be further clarified. Herein, metal-alcohol coordination was evidenced to promote reduction of Bi^III in Bi-based semiconductors (e.g., Bi₂MoO₆ hierarchical microspheres) to generated oxygen vacancies (Ovs) and Bi metal (Bi⁰). Ovs and Bi⁰, rather than widely recognized doping metal ions, play a key role for remarkable enhancement of photocatalytic activity of Bi₂MoO₆, for example of ∼16-fold higher photocatalytic nitrogen reduction activity, which arises from that the Ovs and Bi⁰ can enhance photoexcited charge separation and work as surface active sites. The Ovs possess much greater efficacy than the Bi⁰. Formation of Bi⁰ also induces prominent morphological variation of the microspheres. This work discloses an interesting but neglected phenomenon in alcohothermal synthesis of “metal-doped” Bi-based semiconductors and aims at drawing high attention of relevant researchers.

Hydrogenation of CO₂ into methanol at low-temperature on Cu-based catalysts is of great significance, but remains challenging to enhance activity. In this paper, we report an inverse catalyst constructed with nano-ZrZnO_x supported on Cu particles with outstanding methanol synthesis performance at 220 ℃, two times higher than that of commercial Cu/ZnO/Al₂O₃ catalysts under the same conditions. Detailed structure characterization and performance evaluation demonstrate that the ZrZnO_x mixed oxide serves as the most active oxide-metal interface site for CO₂ hydrogenation. The ZrZnO_x/Cu inverse catalyst increases the weak and medium CO₂ adsorption sites which are further demonstrated responsible to the methanol productivity. In situ DRIFTs studies reveal that the inverse interface accelerates the reduction of asymmetric formate intermediates and prevents the generation of CO. The combination of enhanced CO₂ activation capability and accelerated hydrogenation rate of intermediates over the ZrZnO_x/Cu inverse catalyst probably contribute to the remarkable methanol synthesis performance from CO₂.

Herein, the photocatalysts of metallic Bi-modified TiO₂ microsphere (namely BTO) were synthesized by one-pot solvothermal method. The localized surface plasmon resonance (LSPR) effect of introduced metallic Bi nanoparticles is beneficial to improve the absorption efficiency for visible light, and its surface hot electrons can donate to the valence band of TiO₂ for boosting the separation efficiency of light generated electron-hole pairs. BTO catalysts exhibit the super catalytic activity for visible light-driven CO₂ reduction with H₂O to CH₄. The formation amount and selectivity of CH₄ product over BTO-2 catalyst are 49.12 μmol g⁻¹ and 85.48 % for 4 h, respectively. Based on the results of in-situ DRIFTS and density functional theory calculation, the mechanism for photocatalytic CO₂ reduction is proposed: the visible light-driven LSPR effect on BTO catalyst can boost the key step of CO₂* -to-HCO* for promoting selective generation of CH₄ product. It inspires the design of efficient photocatalysts for CO₂ conversion.

The important role of optimizing the coordination environment of single-atom catalysts (SACs) for selective production of singlet oxygen (¹O₂) in Fenton-like reactions is revealed. Herein, we introduce electron-depletion boron atoms to manipulate the coordination number and atom types of Fe site simultaneously and construct a six-coordination Fe-N₂B₄ catalyst for peroxymonosulfte (PMS) activation. Particularly, it achieves 98.68% ¹O₂ generation selectivity superior to unregulated Fe-N₄ catalyst (64.57%), exhibiting an exceptional bisphenol A (BPA) degradation performance with a reaction rate constant of 0.249 min⁻¹. Experimental and theoretical results unveil that the tailored electronic structure of Fe not only enhances the adsorption selectivity of terminal oxygen atoms in PMS and alters the reaction pathway preference, but also facilitates the electron donation from PMS and lowers the energy barrier for ¹O₂ generation. This work provides a universal strategy for rational and precise modulation of SACs for specific reactive species conversion in environment remediation.

Organic halide transformation is of high importance for fine chemical synthesis and environmental remediation. Integrated photocatalytic platforms open up distinctive reaction pathway for carbon-halogen bond activation/reconstruction. Herein we reveal carbon nitride (CN)-ligated single atom nickel (Ni₁/CN), with accumulated electron on the CN, paves Ni-mediated electron-proton transfer, enabling hydrodehalogenation, along with the catalytic carbon–oxygen (C–O) coupling. The preference for hydrodehalogenation positively correlates with density of electron on CN. EPR measurements suggest photo-generated Ni^I interacts with aryl halides, followed by electron transfer or reductive elimination to give different products. Further kinetic studies on hydrodehalogenation/C–O coupling show the reaction orders of 0.1/0.5 in aryl halide and 1.5/0.03 in (CN) electron, unveiling rate-determining step as oxidative addition to Ni^I and (CN) electron transfer for the two conversions. Our work advances in modulating aryl halide conversion by carrier accumulation on the photoactive support and guides metallaphotocatalytic platform design/operation toward target transformations.

Herein, an asymmetric diatomic site oxygen reduction reaction (ORR) electrocatalyst with atomically dispersed Fe and Cu species co-anchored on porous nitrogen-doped polyhedra carbon was successfully prepared through a facile cooperation of post-adsorption and two-step pyrolysis method. Density functional theory (DFT) calculations reveal that the asymmetric FeCu dual atomic site experiences a symmetry destruction of electron transfer due to the existing Cu-N₄ sites and thus results in the electron redistribution in Fe_SACu_SA/NC, contributing significantly to the optimization of intermediates adsorption and acceleration of kinetics during ORR process. Attributed to the structural advantages of Fe_SA-N₄&Cu_SA-N₄ sites and highly porous carbon matrix, the Fe_SACu_SA/NC catalyst exhibits excellent electrocatalytic ORR performance with half-wave potentials (E_1/2) of 0.86 and 0.88 V versus reversible hydrogen electrode in 0.1 M HClO₄ and 0.1 M KOH solutions as well as high durability. Moreover, Fe_SACu_SA/NC-based H₂/O₂ fuel cell and zinc-air battery present superior performance with high peak power density.

Exploring cheap, eco-friendliness, and highly efficiency photocatalysts for improving the degradation performance of ciprofloxacin (CIP) is a challenge in the environmental remediation field. Herein, 2D/2D ultrathin g-C₃N₄/NH₄V₄O₁₀ (CNNS/NH₄V₄O₁₀) heterojunction is successfully prepared by intercalating g-C₃N₄ nanosheets into the ultrathin NH₄V₄O₁₀ nanobelts. For the optimized 50-CNNS/NH₄V₄O₁₀, the removal rate is 92% for 10 mg·L⁻¹ CIP under simulated solar light, far better than the separated components CNNS and NH₄V₄O₁₀. Moreover, the wide degraded concentration of CIP ranges from 5 to 40 mg·L⁻¹ devotes a prospect of practical application. The mechanism investigation confirms the intercalating action can break the interlaminar bonding linkage of NH₄, which increases the surface NH₄⁺ content and promotes the steered adsorption capacity toward ciprofloxacin through binding to F^- in CIP via H-bonding. This work provides a novel design idea for constructing 2D/2D intercalated nanocomposite for the application in the removal of the deleterious fluoric-containing organic pollutants in water environment.

Bioethanol to middle distillate technologies have offered a unique solution to produce renewable aviation fuel for decarbonizing the hard-to-electrify sectors. Here, we have developed the series of bimetallic Cu- and rare earth-containing (RE) Beta zeolite catalysts that yield high C₃₊ alkene selectivity from ethanol upgrading (>80% selectivity at ∼100% conversion, 623 K). The formation rates of butene isomers to C₅₊ alkenes are linearly correlated with the strength of Lewis acidic RE identity, which follows the sequence of Yb₁₂/Beta >Y₇/Beta > Gd₁₂/Beta > Ce₁₀/Beta > La₁₂/Beta. Rate measurements indicate that the RE selection plays the vital role in altering the rate of the key competitive reactions within the ethanol-to-alkenes reaction network, namely C₄ alcohol dehydration and C-C chain growth, which dictate alkene product distributions. These findings indicate a feasible and promising method for tailoring alkene product distributions from ethanol upgrading, which is of notable significance to the generation of renewable middle distillates.