Precision Chemistry最新文献

γ-Butyrolactone structures are commonly found in various natural products and serve as crucial building blocks in organic synthesis. Consequently, the development of methods for synthesizing γ-butyrolactones has garnered significant interest within the organic synthesis community. In this study, we present a direct and highly efficient approach for the synthesis of γ-butyrolactones from allylic alcohols. Notably, this study represents the first instance of γ-butyrolactone synthesis initiated by radical hydrocarboxylation using CO₂^•–, generated from metal formates, followed by cyclization. This two-step process is achieved through the synergistic interaction of photoredox and hydrogen atom transfer (HAT) catalysis, resulting in the production of γ-butyrolactones with exceptional efficiency. Additionally, when employing α,α-diaryl allylic alcohol derivatives as substrates, the reaction involves 1,2-aryl migration, which occurs concomitantly with CO₂^•– addition, leading to the formation of 4,5-substituted lactones in a good yield. The artificial force induced reaction (AFIR) method identified the preferred 1,2-aryl migration pathway along with potential byproduct pathways, in which the targeted 1,2-migration was found to be the most plausible pathway.

Electroreduction of nitrate (NO₃^–) to ammonia (NH₃) is an environmentally friendly route for NH₃ production, serving as an appealing alternative to the Haber–Bosch process. Recently, various noble metal-based electrocatalysts have been reported for electroreduction of NO₃^–. However, the application of pure metal electrocatalysts is still limited by unsatisfactory performance, owing to the weak adsorption of nitrogen-containing intermediates on the surface of pure metal electrocatalysts. In this work, we report thiol ligand-modified Au nanoparticles as the effective electrocatalysts toward electroreduction of NO₃^–. Specifically, three mercaptobenzoic acid (MBA) isomers, thiosalicylic acid (ortho-MBA), 3-mercaptobenzoic acid (meta-MBA), and 4-mercaptobenzoic acid (para-MBA), were employed to modify the surface of the Au nanocatalyst. During the NO₃^– electroreduction, para-MBA modified Au (denoted as para-Au/C) displayed the highest catalytic activity among these Au-based catalysts. At −1.0 V versus reversible hydrogen electrode (vs RHE), para-Au/C exhibited a partial current density for NH₃ of 472.2 mA cm^–2, which was 1.7 times that of the pristine Au catalyst. Meanwhile, the Faradaic efficiency (FE) for NH₃ reached 98.7% at −1.0 V vs RHE for para-Au/C. The modification of para-MBA significantly improved the intrinsic activity of the Au/C catalyst, thus accelerating the kinetics of NO₃^– reduction and giving rise to a high NH₃ yield rate of para-Au/C.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have garnered widespread interest in the scientific community and industry for their exceptional physical and chemistry properties, and great potential for applications in diverse fields including (opto)electronics, electrocatalysis, and energy storage. Chemical vapor deposition (CVD) is one of the most compelling growth methods for the scalable growth of high-quality 2D TMDs. However, the conventional CVD process for synthesis of 2D TMDs still encounters significant challenges, primarily attributed to the high melting point of precursor powders, and achieving a uniform distribution of precursor atmosphere on the substrate to obtain controllable smaple domains is difficult. The spin-coating precursor mediated chemical vapor deposition (SCVD) strategy provides refinement over traditional methods by eliminating the use of solid precursors and ensuring a more clean and uniform distribution of the growth material on the substrate. Additionally, the SCVD process allows fine-tuning of material thickness and purity by manipulating solution composition, concentration, and the spin coating process. This Review presents a comprehensive summary of recent advances in controllable growth of 2D TMDs with a SCVD strategy. First, a series of various liquid precursors, additives, source supply methods, and substrate engineering strategies for preparing atomically thin TMDs by SCVD are introduced. Then, 2D TMDs heterostructures and novel doped TMDs fabricated through the SCVD method are discussed. Finally, the current challenges and perspectives to synthesize 2D TMDs using SCVD are discussed.

On-surface synthesis has emerged as a powerful strategy to fabricate unprecedented forms of atomically precise graphene nanoribbons (GNRs). However, the on-surface synthesis of zigzag GNRs (ZGNR) has met with only limited success. Herein, we report the synthesis and on-surface reactions of 2,7-dibromo-9,9′-bianthryl as the precursor toward π-extended ZGNRs. Characterization by scanning tunneling microscopy and high-resolution noncontact atomic force microscopy clearly demonstrated the formation of anthracene-fused ZGNRs. Unique skeletal rearrangements were also observed, which could be explained by intramolecular Diels–Alder cycloaddition. Theoretical calculations of the electronic properties of the anthracene-fused ZGNRs revealed spin-polarized edge-states and a narrow bandgap of 0.20 eV.

The two-electron oxygen reduction reaction (2e^–-ORR) can be exploited for green production of hydrogen peroxide (H₂O₂), but it still suffers from low selectivity in an acidic electrolyte when using non-noble metal catalysts. Here, inspired by biology, we demonstrate a strategy that exploits the micellization of surfactant molecules to promote the H₂O₂ selectivity of a low-cost carbon black catalyst in strong acid electrolytes. The surfactants near the electrode surface increase the oxygen solubility and transportation, and they provide a shielding effect that displaces protons from the electric double layer (EDL). Compared with the case of a pure acidic electrolyte, we find that, when a small number of surfactant molecules were added to the acid, the H₂O₂ Faradaic efficiency (FE) was improved from 12% to 95% H₂O₂ under 200 mA cm^–2, suggesting an 8-fold improvement. Our in situ surface enhanced Raman spectroscopy (SERS) and optical microscopy (OM) studies suggest that, while the added surfactant reduces the electrode’s hydrophobicity, its micelle formation could promote the O₂ gas transport and its hydrophobic tail could displace local protons under applied negative potentials during catalysis, which are responsible for the improved H₂O₂ selectivity in strong acids.

Single-atom catalysts (SACs) provide an opportunity to elucidate the catalytic mechanism of complex reactions in heterogeneous catalysis. The low-temperature water–gas shift (WGS) reaction is an important industrial technology to obtain high purity hydrogen. Herein, we study the catalytic activity of Pt₁@Ti₃C₂T₂ (T = O, S) SACs, where one subsurface Ti atom with three T vacancies in the functionalized Ti₃C₂T₂ (T = O, S) MXene is substituted by one Pt atom, for the low-temperature WGS reaction, using density functional theory (DFT). The results show that Pt₁@Ti₃C₂T₂ provides an excellent platform for the WGS reaction by its bowl-shaped vacancy derived from the Pt₁ single atom and three T defects surrounding it. Especially, Pt₁@Ti₃C₂S₂ SAC has higher catalytic performance for the WGS reaction, due to the weaker electronegativity of the S atom than the O atom, which significantly reduces the energy barrier of H* migration in the WGS reaction, which is often the rate-determining step. In the most favorable redox mechanism of the WGS reaction on Pt₁@Ti₃C₂S₂, the rate-determining step is the dissociation of OH* into O* and H* with the energy barrier as low as 1.12 eV. These results demonstrate that Pt₁@Ti₃C₂S₂ is promising in the application of MXenes for low-temperature WGS reactions.