ACS Catalysis 最新文献

The surface nitrogen concentration governs interfacial electron transfer in nitrogen-doped carbon-wrapped Fe₃C catalysts for Fischer–Tropsch synthesis (FTS). By controlling surface nitrogen density at fixed total nitrogen content, we demonstrate the nitrogen-sufficient surface in Fe₃C@C (Fe@NC-S) intensifies interfacial electron flux via enhanced Fe–N coordination. This yields a 4-fold increase in CO conversion rate (109.4 vs 27.4 μmol_CO g_Fe^–1 s^–1) relative to nitrogen-deficient Fe@NC, while preserving identical C₅₊ selectivity (42.1%). Spectroscopic and computational studies reveal the nitrogen-enriched surface reduces Fe₃C → C electron leakage (+1.619 e vs +1.906 e) and boosts Fe₃C → CO* back-donation (+0.264 e vs +0.243 e), concentrating electron density at Fe₃C active sites to drive CO activation without altering chain-growth kinetics. This work establishes surface nitrogen engineering as a viable strategy for next-generation FTS catalysts with activity–selectivity synergy.

The selective hydrogenation of CO₂ to methanol represents a promising strategy for mitigating CO₂ emissions while simultaneously producing valuable chemicals and fuels. Nonetheless, achieving high methanol selectivity and long-term catalyst stability remains a significant challenge, especially for classic CuZn-based catalysts. In this study, we introduce a simple postsynthesis method to generate abundant hydroxyl nests on pure silicate zeolite (S-1), designated as S-1-treated. Uniform CuZn nanoparticles were subsequently encapsulated within the S-1-treated zeolite via wetness impregnation. The obtained CuZn@S-1 catalyst exhibited high catalytic performance, achieving a stable methanol space-time yield (STY) of 10.1 mmol g_cat^–1 h^–1 and a methanol selectivity of 91.0%. Moreover, this catalyst demonstrated good stability, maintaining performance for 240 h on-stream. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses further confirmed the preferential formate reaction pathway for methanol formation over that of the CuZn@S-1 catalyst. This research provides a well-defined structure–activity relationship, underscoring the efficacy of zeolite-supported catalysis in addressing complex chemical transformations.

Directed C–H annulation with alkynes has emerged as one of the most reliable strategies for the step-economical construction of heterocycles, while precise control of regio- and chemoselectivity remain appealing and challenging. In this work, we developed haloalkynes that enable switched regiodivergent and chemoselective C–H annulation with amides that tolerates diverse functional groups, including strongly coordinating heterocycles. Further synthetic applications were demonstrated by the concise delivery of a 5-HT3 antagonist analogue and the site-selective modification of complex pharmaceuticals that contain diverse competing coordination sites.

Aporphine alkaloids (APAs) are renowned for their diverse pharmacological activities, but their practical preparation is hindered by challenges, such as poor chiral control and low coupling efficiency, making their production largely dependent on plant extraction. Here, we present a streamlined, modular chemoenzymatic strategy that integrates biocatalysis with photoinduced coupling to efficiently synthesize both natural and unnatural APAs from inexpensive, readily available substrates. This platform employs a sequential enzymatic reaction using engineered imine reductase and cocaine N-methyltransferase to convert 2’-halogenated 1-benzyl-dihydroisoquinolines into (S)-1-benzyl-tetrahydroisoquinoline precursors, followed by catalyst-free photoinduced coupling to construct diverse APA frameworks. Notably, the highly efficient method enables the gram-scale synthesis of (S)-nuciferine in just four steps, demonstrating its practical applicability. By simplifying complex synthesis, enhancing stereoselectivity, and reducing reliance on rare plant sources, this approach offers a powerful platform for APA production and serves as a broadly applicable model for the synthesis of related complex natural products.

1,4-Metal/hydrogen migration is a flexible strategy that not only activates remote C–H bonds but also mediates regioselective coupling reactions. We describe here an intermolecular coupling between allenes and alcohols to access β,γ-unsaturated ketones via tandem ruthenium catalysis. The reaction occurs via migratory hydroacylation of allenes with an in situ-generated aldehyde through the dehydrogenation of the alcohols. This formal dual C–H functionalization reaction enables one-step efficient synthesis of β,γ-unsaturated ketones from nonchelating alcohols using a commercially available catalyst and reagent. Unusual β-regioselectivity has been achieved with C–C coupling at the central sp-hybridized carbon of allenes. Moreover, β-regioselective migratory hydroacylation of allenes with nonchelating aldehydes has also been disclosed. The detailed mechanism has been proposed based on the control experimental and computational studies involving hydrogen transfer catalysis and key 1,4-ruthenium hydrogen migration.

Bismuth-based electrocatalysts are widely recognized for their high formate selectivity in the CO₂ reduction reaction (CO₂RR), primarily attributed to the exposure of the Bi (012) facet. We demonstrate that anisotropic alloying with yttrium stabilizes metallic Bi and shifts the active facets to Bi (00z). Bi_90.4Y_9.6 nanoparticles (NPs) with anisotropic lattice strain exhibit a Faradaic efficiency (FE_formate) greater than 90% between −1.1 and −1.4 V vs reversible hydrogen electrode (RHE), attaining ∼95% at −1.3 V. Facet-specific structural and microscopic analyses show Y incorporation along the <00z> axis, which induces localized tensile and compressive strain, promoting the exposure of (003) facet, in contrast to (012) in the relatively strain-free Bi₁₀₀ NPs. In situ Raman spectroscopy indicates the reversible formation of Bi₂O₂CO₃ at low cathodic potentials and the dominance of metallic Bi at potentials coinciding with high FE_formate. First-principles calculations reveal that strong Bi–Y d-p orbital hybridization and Bi site metallization generate electron-deficient Y-centers, promoting CO₂ activation through O–Y interactions and selective stabilization of the adsorbed HCOO intermediate. These findings underscore the role of lattice strain engineering and electronic modulation in optimizing the CO₂RR activity.

The anion exchange membrane water electrolyzer (AEMWE) is a promising technology for cost-effective hydrogen production. To promote its development and adoption, targeted efforts are focused on finding non-platinum group metal (non-PGM) electrocatalysts that efficiently facilitate the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Nickel sulfides (NiS) are effective OER catalysts; however, they suffer due to leaching-related instability at electrolyzer stack operational conditions. We introduce a rational non-PGM design that enhances stability during the OER while excelling at the HER, showcasing molecular-level insights for a scalable AEMWE zero-gap stack device. NiS coating is applied to the Al-metal–organic framework supported by 3D porous nickel foam (NSMA), leading to charge localization at the interface, which helps in OER by requiring only 322 millivolts at 100 mA cm^–2. The main innovation in the NSMA design is a controlled electroreduction process that converts the Millerite phase into Ni₃S₂, a catalyst (rNSMA). This transformation leads to charge delocalization at the surface and a low overpotential of −80 mV at −100 mA cm^–2 for the HER. In a full cell, this catalyst duo requires an overpotential of 1.49 V, outperforming the commercial Pt/Ru catalyst pair at 1.58 V. In a scaled-up 12.96 cm² AEM electrolyzer single-cell stack, current density rose from 398 to 1062 mA/cm², maintained for over 100 h at high temperatures, achieving 99% Faradaic efficiency and 100% hydrogen purity. The AEM electrolyzer cell shows a good energy efficiency of 45.50 kWh/kg and a cell efficiency of 86.59%. Detailed studies, including DFT analyses, revealed that electronic structure modification enhances charge delocalization, driving its impressive performance on an industrially significant scale.

Spin polarization manipulation has been exploited as an effective strategy to regulate the catalytic efficiency, especially for the reactions that involve spin state transition. Chiral structure construction provides an interesting pathway to realize spin polarization through a chiral-induced spin selectivity (CISS) effect without complicated materials design and external magnetic field application. Most of the CISS-related studies have been carried out at room temperature, with the effect of the temperature often overlooked. Herein, chiral BiOBr was synthesized, and the CISS effect could be applied for boosting photocatalytic HBrO production, which is attributed to the suppressed recombination of photogenerated carriers. More importantly, the CISS effect was demonstrated to be temperature dependent and could be strengthened at an elevated temperature. The elaborate mechanism study also shows that electrons with a specific spin orientation would facilitate electron transfer to O₂ for promoting the subsequent reactions. This work offers solid evidence for the temperature dependency of the CISS effect and could benefit the exploration of more untapped paradigms for photocatalysis through spin polarization.

Using carbon dioxide for chemical and fuel production may be an attractive strategy to reduce the carbon footprint of the chemical and transportation industries. Electrochemical CO₂ reduction (eCO₂R) using renewable energy enables the generation of CO and C₂H₄, which can be combined thermocatalytically to generate more complex chemical products. However, eCO₂R is often difficult to couple with organometallic catalysis due to drastically different reaction conditions. Herein, we present a system to synthesize industrially relevant chemicals, methyl and butyl propanoate and 3-pentanone, the latter being a promising fuel additive with an octane number of 107. Propanoates and 3-pentanone are produced by coupling CO and C₂H₄, and, in the latter case, H₂, with Pd-based organometallic catalysts, with precursors being sourced from CO₂ by using Cu and Ag gas diffusion electrodes. These processes show a current efficiency of up to 35% and a CO₂ conversion of up to 20%.

Elucidating the dynamic evolution of single-atom catalytic sites remains a fundamental challenge in advancing single-atom catalysis. While current studies primarily focus on stimulus-responsive structural transformations induced by external perturbations (e.g., electrochemical potential variations), the intrinsic self-adaptive mechanisms of active sites under ambient reaction conditions remain largely unexplored. Here, we report a reactant-induced dynamic coordination evolution in a nitrogen/oxygen dual-coordinated cobalt single-atom catalyst (Co–N₃O₁) during peroxymonosulfate-based advanced oxidation processes (PMS-AOPs). Through operando X-ray absorption spectroscopy (XAS) combined with density functional theory (DFT) calculations, we identify a two-step reversible structural transition from the initial Co–N₃O_cat configuration to an O_PMS═Co–N₃ intermediate upon PMS activation, which subsequently reverts to the original Co–N₃O_cat state during phenol oxidation. This dynamic restructuring arises from a spontaneous d–p orbital rearrangement between Co 3d orbitals and O 2p orbitals of coordinating oxygen species, which selectively stabilize high-valent Co(IV)═O species. The optimized catalyst exhibits a 4-fold increase in activity compared to conventional Co–N₄ SACs, along with stable operation exceeding 120 h and effective treatment of real industrial coal chemical wastewater. This work provides atomically resolved evidence of stimulus-free, reactant-induced active-site dynamics and establishes a paradigm for designing adaptive single-atom catalysts with broad applicability in environmental and energy-related applications.