Applied Catalysis B: Environmental最新文献

Glucose-assisted supramolecule self-assembly of melamine and cyanuric acid in the presence of Fe(NO₃)₃ combined with thermal polymerization is designed to fabricate C-rich g-C₃N₄-embedded interlayer single-atomic Fe−N₄ sites catalyst (Fe₁/C-CN). Fe₁/C-CN exhibits outstanding photo-Fenton-like catalytic oxidation activity towards typical recalcitrant organic micropollutants. For example, the pseudo-first-order kinetic constant of Fe₁/C-CN photo-Fenton-like system is 7.5 and 21.1 times higher than Fe₁/C-CN photocatalysis and Fenton-like systems in degradation of p-nitrophenol, and TOC removal efficiency reaches up to 100% after reaction proceeds for 4 h. Mechanism studies reveal that synergy of maximum Fe atom utilization efficiency and boosted photoexcited charge separation dynamics accelerates regeneration of ≡Fe(II) and efficient H₂O₂ activation of Fe₁/C-CN, leading to plentiful active oxygen species for deep oxidation of organic micropollutants. Fe₁/C-CN also shows a robust reusability in long-term remediation of organic micropollutants, attributing to interlayer Fe−N coordination interactions for preventing single Fe atoms from agglomeration and leaching to reaction media.

Direct CO₂ hydrogenation to higher alcohols (HA) is a promising route for high-value utilization of waste CO₂, but developing active and stable catalysts remains a grand challenge. For this reaction, constructing multifunctional interfaces as active sites is required to fulfill controllable C-C coupling of alkyl and CO*/CH_xO* species. Herein, we report a PdFe catalyst with abundant PdFe alloy-Fe₅C₂ interfaces via a PdFe alloy induced FeO_x carbidization process, which can achieve HA yield of 86.5 mg g_cat⁻¹ h⁻¹ with 26.5% selectivity at 300 ºC, 5 MPa, and 6000 mL g_cat⁻¹ h⁻¹. The accelerated deactivation test unveils the PdFe catalyst exhibits better durability than the widely studied CuFe based catalysts against harsh conditions. Multiple in-situ characterization results unveil a synergetic mechanism for HA synthesis at the PdFe alloy-Fe₅C₂ interfaces, where PdFe alloy is responsible for CO formation and non-dissociative activation, while Fe₅C₂ phase promotes CO dissociation and chain propagation.

Precisely constructing Pt single atom catalyst (SACs) with fine-tuned chemical environments is a vitally challenging issue, which has attracted peoples’ attentions. The activation of lattice oxygen linked to active sites is also a great challenge to heterogeneous catalysis. Herein, via a cage-encapsulating strategy, Pt single atom (SA) was accurately constructed by dual nanospace confinement of three-dimensional ordered macroporous (3DOM) CeO₂ pore and Ce-MOFs nanocages. During calcination, CeO₂ derived from Ce-MOF restricted the migration of Pt SA and prevented its agglomeration. With the construction of CeO₂ nanocage, more active Pt-O₂ bond was created. More active lattice oxygen was linked to Pt single atom. DFT calculation also confirmed VOCs molecules were more easily absorbed on the catalyst surface and CO was more easily oxidized to CO₂. The 90% conversion temperature (T₉₀) of Pt₁/CeO₂ @CeO₂-0.2 (T₉₀ = 268 °C) was 81 °C lower than the T₉₀ of Pt₁/CeO₂ (T₉₀ = 349 °C) on the catalytic combustion of benzene.

Developing highly efficient photocatalysts that selectively convert NO pollutants to NO₃¯ while storing metabolic nitrogen for crops remains a great challenge. Simultaneously, there is a dearth of research investigating the relationship between the chemical environment and the activity of catalytic sites. Herein, an efficient impregnation approach to access atomically dispersed Sr single atoms supported on Nb₂O₅ is reported; meanwhile, various ligands (-Cl, -Br, -OH) are employed to customize the local structure. The results show that Cl-Sr/Nb₂O₅ exhibits excellent catalytic performance in eliminating NO, which is significantly superior to other catalysts. The introduction of Sr atom and ligand increases the energy barrier of NO₂ formation, thus improving the selectivity of converting NO to NO₃¯. This study highlights the importance of precisely designing the catalytic site at the atomic level, and the obtained insights may serve as a valuable guide for developing future catalyst designs.

CO₂ conversion to CO via the reverse water-gas shift (RWGS) reaction is a promising source of syngas for subsequent synthesis of liquid fuels and chemicals. Herein, we present the synthesis of catalysts containing Au supported on hydroxylated Na-modified ZrO₂, with Au amounts ranging from 0.05 to 1 wt%. Systematic investigations reveal the formation of cooperative Au/Na sites at the interface. These sites cooperate synergistically to activate CO₂ and generate a high surface density of carboxylate-like species, which serve as highly active intermediates for CO formation. It was found that the RWGS reaction on the catalyst with low Au loading proceeds mainly via a carboxylate pathway, with bidentate formate acting as spectators. At higher Au loading, the bidentate formate pathway contributes somewhat to CO formation alongside the carboxylate pathway. Based on temporal analysis of products, we emphasize the significant roles of H₂ spillover and the metal-support interface in the RWGS reaction.

Selective, low-overpotential and high Faradaic efficiency electroreduction of CO₂ to ethanol is in prominent global demand and lies in structuring, loading, and modulating the coordination states of Cu single atom catalysts (SACs) with support matrix. Here, the low-temperature (160 °C) synthesis of Cu–SACs–N-doped carbons dots (Cu–SACs–N–CQDs) is reported via Cu–dopamine complex process. The optimized Cu–SACs–N–CQDs electrocatalyst brings remarkably high Faraday efficiency (> 80%) and selectivity for ethanol with 50 h operation stability, which far exceeds previous results in terms of overpotential, stability, and Faraday efficiency. Surprisingly, the Faraday efficiency and selectivity of ethanol are highly sensitive to the coordination states of copper SACs with variation of Cu loadings. Operando X-ray absorption spectroscopy indicates in situ-generated neighboring metallic Cu–Cu atom coordination as real catalytic active sites from isolated single Cu atom during CO₂ reduction, which favors the ethanol selectivity.

To break the restriction of SO₅^2- as the essential initiator in O₃/PMS reaction during water purification, F-Fe-Zn-MCM-41 (FFeZn-M) was designed to enhance ibuprofen (IBP) degradation during O₃/PMS process. The great electronegativity difference between Fe and Zn created an electron flow from Zn to Fe, which was further enhanced by electron withdrawing Si-F group. FFeZn-M changed the traditional interaction between PMS and O₃. PMS would be adsorbed on the surface of Zn and acted as an electron donor. Meanwhile, O₃ received electrons from Fe site and was activated into ROS. With •OH and ¹O₂ as the main ROS, FFeZn-M/O₃/PMS process achieved the complete IBP removal and a 60.9% mineralization rate, which was significantly higher over those of FFeZn-M/O₃ and FFeZn-M/PMS processes. FFeZn-M/O₃/PMS behaved better at weak acidic and neutral condition rather than the basic condition required by conventional O₃/PMS process. This study offered a novel catalyst design strategy for O₃/PMS.

In recent years, due to the substantial emission of CO₂, global warming has become more severe, and there is an urgent need to develop technologies to reduce greenhouse gas CO₂ emissions. Converting CO₂ into higher alcohols is a promising process, as it not only produces valuable chemicals but also utilizes CO₂ as feedstock. Currently, most reported catalytic approaches are based on direct hydrogenation of CO₂ to synthesize higher alcohols. However, the synthesis of higher alcohols involves multiple steps, requiring catalysts with multiple functional sites and their synergistic interactions are crucial. Nevertheless, controlling catalysts at the nanoscale poses challenges, hindering the design of efficient multi-site catalysts. An alternative approach worth considering is to perform a tandem of multiple well-established catalytic reactions (e.g., methanol synthesis, CO₂-Fischer-Tropsch-Synthesis, RWGS, syngas conversion, olefin hydration, etc.) to indirectly achieve the conversion of CO₂ into higher alcohols, instead of direct CO₂ hydrogenation. Therefore, in this review, these alternative strategies of higher alcohols synthesis are discussed, and their potential is evaluated. First, thermodynamic analysis, the selective adjustment strategies, and the current challenges faced for direct CO₂ hydrogenation are introduced. Then, physical integration of multiple catalysts as a feasible strategy to endow the catalyst with multifunctional properties is discussed. Subsequently, several feasible routes of CO₂ conversion into higher alcohols and the advanced catalysts employed for each pathway are summarized. Finally, merits and limitations of the different approaches are provided, emphasizing the great potential the tandem reaction strategy holds for the efficient synthesis of higher alcohols by CO₂ conversion.

Supramolecule self-assembly of dicyandiamide and uracil followed by thermal polymerization route is designed to prepare carbon atom self-doped g-C₃N₄ (CCN_x), and then wet reduction is applied to fabricate Pd single atoms (Pd₁) and nanoparticles (Pd_NPs) co-anchored CCN_x heterojunctions (Pd_1+NPs/CCN_x). In Pd_1+NPs/CCN_x structure, interlayer Pd−N₄ coordination is the most favorable for chemically stabilizing Pd₁, while Pd_NPs accumulate on the in-plane of CCN_x. Pd_1+NPs/CCN_x heterojunctions exhibit remarkably enhanced photocatalytic H₂ evolution reaction (HER) activity, and HER rate and AQY value reach up to 24.1 mmol g⁻¹ h⁻¹ and 17.1% (400 nm) over the optimized Pd_1+NPs/CCN_x catalyst. Mechanism studies unveil that synergy of as-built interlayer N−Pd−N electron transfer channels at the atomic-scale and surface Mott–Schottky effect of small Pd nanoparticles notably accelerates migration of photogenerated electrons, which leads to plentiful electrons accumulation around Pd single atoms and small nanoparticles to decrease the energy barrier of H* activation and boost HER photodynamics significantly.

Nanoporous Fe-Pd alloy with metastable face-centered cubic (fcc Fe-Pd) phase is prepared by electrochemical dealloying as an electrocatalyst for hydrogen evolution reaction (HER). The nanoporous fcc Fe-Pd alloy achieves an overpotential of 58 mV at 10 mA cm⁻² in 1 M KOH, outperforming those of stable body-centered cubic Fe-Pd alloy (bcc Fe-Pd) and commercial Pt/C catalyst. Density functional theory calculation reveals that the metastable fcc structure can tailor the coordination environment and electronic structure of Pd active sites in Fe-Pd alloy. As a result, the d‐band center of Pd active site shifts away from the Fermi level, which weakens the Pd-H interaction and reduces the energy barrier of water dissociation. In addition, the fcc Fe-Pd exhibits good mechanical properties, which maintains the catalytic performance in the deformation state. This work broadens the idea for designing and preparing HER catalysts via metastable phase structure design.