Applied Catalysis B: Environmental最新文献

Direct conversion of CO₂ into higher alcohols (C₂₊OH) is highly desirable, but rather challenging due to requiring the synergetic action of C-C coupling and CO insertion. Here, we developed a new K-CuZnAl/Zr-CuFe composite, which gave CO₂ conversion and C₂₊OH selectivity of 40.6% and 22.4% respectively, while CO selectivity is only 10.3% at 320 °C, 4 MPa and 6000 mL g_cat⁻¹ h⁻¹. The C₂₊OH STY can reach 195.1 mg g_cat^–1 h^–1, and is well maintained within 200 h at higher GHSV of 24000 mL g_cat⁻¹ h⁻¹. Introduction of K-CuZnAl and decrease of the contact distance of K-CuZnAl and Zr-CuFe boost the formation and subsequent conversion of CO* intermediate. In addition, doping small amounts of Zr into CuFe catalyst hinders the phase separation of Cu and Fe species by enhancing their interface interaction. As a result, the CH_x * species generated on iron carbide through CO* dissociative activation quickly reacts with the non-dissociative adsorbed CO* on adjacent Cu to produce more C₂₊OH.

This study explores the fabrication and characterization of mesoporous nitrogen-doped carbon replicas (MNCs) as Ru catalyst supports for CO₂ hydrogenation to formate. MNC supports with a cubic Ia3d-like structure were successfully synthesized from a KIT-6 template. The mesoporosity, N content, and N states in the MNCs differed according to the precursor type, which substantially influenced the stability of single-atom Ru catalysts during CO₂ conversion. In hydrogenation tests, the Ru/MNC prepared using acrylonitrile precursor (Ru/MNC-A) demonstrated the best stability, whereas the Ru/MNCs prepared using pyrrole and melamine exhibited low activity owing to Ru agglomeration and limited reactant diffusion, respectively. The excellent stability of Ru/MNC-A resulted from Ru migration and rearrangement, as evidenced by near edge X-ray absorption fine structure analyses. Ru/MNC-A and Ru/MNC-A-400 achieved an outstanding turnover number of 69,000 in CO₂ hydrogenation over 72 h. Remarkably, the Ru/MNC-A catalyst demonstrated exceptional stability, attaining a TON of 315,840 over 360 h.

Proton exchange membrane water electrolysis (PEMWE) is an environmentally benign technology for large-scale hydrogen production. Despite many catalysts being developed to replace Pt, successful development of low-cost catalysts that meet the balance of performance and durability is limited. In this work, atomically dispersed Ru on Ni catalyst-integrated porous transport electrodes were fabricated by a simple electrodeposition. With a trace amount of Ru (< 0.05 mg_Ru·cm⁻²), the Ni_98.1Ru_1.9 cathode catalyst exhibited an overpotential of 35 mV at –10 mA·cm⁻² with excellent stability. Density functional theory calculation revealed that the high performance was driven by optimized adsorption strength and improved mobility of hydrogen on the catalyst surface. The Ni_98.1Ru_1.9 electrode was further verified in a PEMWE cell and resulting performance (6.0 A·cm⁻² at 2.25 V_cell) and stability (0.13 mV·h⁻¹ decay rate at 1 A·cm⁻²) surpassed previously reported non-Pt and even Pt electrodes, demonstrating its readiness as an advanced cathode to replace Pt.

Cu-based catalysts have been widely used in ammonia-selective catalytic reduction (NH₃-SCR) of NO_x for their excellent low temperature denitration performance. However, the aggregation of Cu species has been a troubling problem in catalyst design. Herein, spherical zeolite ZSM-5 confined Cu nanoclusters Cu@ZSM-5 has been successfully constructed via in-situ self-assembly process. It exhibits high specific surface area (373 m²g⁻¹), higher concentration of Cu⁺, rich oxygen vacancies and more acid sites compared with Cu/ZSM-5. The results indicate that strong acid sites of carrier could improve high-temperature catalytic activity, and Cu species as active sites could significantly improve both the low-temperature and high-temperature catalytic reduction activity of NO_x, especially, its performance maintained unchanged after coating on honeycomb ceramics. Thanks to strong surface acidity sites and the confinement effect, the Cu@ZSM-5 exhibited super activity, high N₂ selectivity, wide operating temperature window and strong water resistance.

Direct photocatalytic hydrogen evolution from seawater is an appealing approach to migrate the crisis of carbon emissions. However, limited solar energy utilization and catalyst poisoning are two obstacles to the hydrogen evolution from seawater. Herein, a microneedle module that integrates with solar-driven vapor generation and vapor splitting to realize directly solar-driven seawater splitting has been designed. The photothermal pedestal with high-adhesive superhydrophobicity not only provides sufficient vapor generation, but also isolates harmful substances such as salt in seawater from photocatalysts. Besides, the pedestal with superhydrophobicity and photothermal effect can provide high-temperature gas–solid reaction sites for photocatalyst microneedles to thermodynamically promote the desorption of hydrogen. Thus, the integrated module exhibits a remarkable hydrogen evolution rate of 200.5 mmol g^–1 h^–1 in seawater. The rational design of multifunctional interfaces opens a new window for high-efficiency direct seawater splitting to hydrogen evolution.

Phosphorization of molybdates has been shown to promote hydrogen evolution reaction (HER) activity but is usually detrimental to oxygen evolution reaction (OER) activity, frustrating efforts to create bifunctional HER/OER electrocatalysts. Herein, we show that Fe₂O₃-modulated P-doped CoMoO₄ on nickel foam (Fe-P-CMO) is an excellent bifunctional HER/OER electrocatalyst in alkaline media, with the adverse effect of phosphorization on the OER activity of CoMoO₄ being countered via Fe₂O₃ introduction. An alkaline splitting electrolyser assembled directly using the self-supporting Fe-P-CMO electrode possessed outstanding long-term durability with ultralow cell voltages of 1.48 and 1.59 V required to achieve current densities of 10 and 100 mA cm⁻², respectively. Detailed experimental investigations showed that during HER, P-doped CoMoO₄ in Fe-P-CMO underwent surface reconstruction with the in-situ formation of Co(OH)₂ on the P-CoMoO₄ (Co(OH)₂/P-CoMoO₄). During OER, P-doped CoMoO₄ was deeply reconstructed to CoOOH with the complete dissolution of Mo, leading to the in-situ formation of Fe₂O₃/CoOOH heterojunctions.

Ag/MnO_x catalysts have great prospects for practical application in ozone decomposition due to their excellent activity and water resistance; yet, improving the stability of Ag/MnO_x catalysts for ozone decomposition remains challenging. Here, the addition of alkali metals significantly improved the stability of 2%Ag/MnO₂ catalyst for ozone decomposition under humid conditions. Alkali metals donate electrons to Ag nanoparticles through oxygen bridges, forcing Ag active sites to become hydroxylated by promoting the dissociation of H₂O molecules, and finally forming new stable hydroxylated Ag active sites (Ag-O(OH)_x-K). The O₂^2- species on the new active sites of the 2%K-2%Ag/MnO₂ catalyst can easily desorb; therefore, the hydroxylated active sites can remain stable. These factors are key to the stable ozone decomposition activity of 2%K-2%Ag/MnO₂ catalyst in humid gas. This study represents a critical step towards the design and synthesis of high-stability catalysts for ozone decomposition.