With the increase in energy demand and worldwide natural environment crises, it is imperative to develop green and sustainable energy systems to produce clean fuels and chemicals, which can replace fossil fuels and reduce carbon dioxide emissions. [1][2][3] A promising strategy is to develop advanced electrochemical technologies that can convert some common molecules (e.g., water, carbon dioxide, and nitrogen) into high-value chemical products (e.g., hydrogen, hydrocarbons, oxygenates, ammonia, and carbonates). [4][5][6][7] The important energy-related electrocatalytic reactions, including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), nitrogen reduction reaction (NRR), carbon dioxide reduction reaction (CO 2 RR), are the key conversion routes. In the complex processes for the electrocatalytic reactions, an efficient, highly selective, and stable electrocatalyst plays a pivotal role in speeding up the reaction kinetics and decreasing the overpotential, [5,8,9] which can enhance the sustainable energy conversion efficiency. Over the past few decades, tremendous progresses have been made in the establishment of electrocatalysts preparation and fundamental catalytic mechanisms. [6,7,[9][10][11][12][13][14][15][16][17][18] Nevertheless, those breakthroughs still stay at the stage of experimental synthesis and lack of indepth understanding of fundamental principles of the active site on the catalyst surface and catalytic reactions mechanisms, which seriously limits the development of efficient catalysts. Researchers are full of enthusiasm about preparation of advanced catalysts with ideal properties, expecting to establish the composition-structure-function relationships. Density functional theory (DFT) calculations are based on quantum mechanics, which can calculate the electronic structure of the whole catalytic system. It is probably the most powerful computational approach to investigate the structure-activity relationships of electrocatalysts at atomic level. With the rapid advances of computer technology, DFT calculations have created tremendous opportunities in shedding light on the electrocatalytic mechanisms and predicting promising catalysts. [19,20] Identification of the active sites and understanding of the reaction mechanisms are the two key aspects for the study of electrocatalytic reactions. [21] For the former, the experimental approach for identifying active sites is indirect by prepared specified catalysts and establishing definite correlations between catalytic performances and controllable factors. [22,23] Actually, many intermediate states of electrocatalytic
Photothermal therapy triggered by near‐infrared light in the second biowindow (NIR‐II) has attracted extensive interest owing to its deeper penetration depth of biological tissue, lower photon scattering, and higher maximum permissible exposure. In spite of noble metals showing great potential as the photothermal agents due to the tunable localized surface plasmon resonance, the biological applications of platinum are rarely explored. Herein, a monocomponent hollow Pt nanoframe (“Pt Spirals”), whose superstructure is assembled with three levels (3D frame, 2D layered shells, and 1D nanowires), is reported. Pt Spirals exhibit outstanding photothermal conversion efficiency (52.5%) and molar extinction coefficients (228.7 m2 mol−1) in NIR‐II, which are much higher than those of solid Pt cubes. Simulations indicate that the unique superstructure can be a significant cause for improving both adsorption and the photothermal effect simultaneously in NIR‐II. The excellent photothermal effect is achieved and subsequently verified in in vitro and in vivo experiments, along with superb heat‐resistance properties, excellent photostability, and a prominent effect on computed tomography (CT) imaging, demonstrating that Pt Spirals are promising as effective theranostic platforms for CT imaging‐guided photothermal therapy.
O-heterocycles have wide applications, and their efficient and green synthesis is very interesting. Herein, we report hydrogen-bonding catalyzed ring-closing metathesis of aliphatic ethers to O-heterocycles over ionic liquid (IL) catalyst under metal-and solvent-free conditions. The IL 1butylsulfonate-3-methylimidazolium trifluoromethanesulfonate ([SO 3 H-BMIm][OTf]) is discovered to show outstanding performance, better than the reported catalysts. An interface effect plays an important role in mediating the reaction rate due to the immiscibility between the products and the IL catalyst, and the products can be spontaneously separated. NMR analysis and DFT calculation suggest that a pair of cation and anion of [SO 3 H-BMIm][OTf] could form three strong Hbonds with an ether molecule, which catalyze the ether transformation via a cyclic oxonium intermediate. A series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines and dioxane can be obtained from their corresponding ethers in excellent yields (e.g., > 99 %). This work opens an efficient and metal-free way to produce O-heterocycles from aliphatic ethers.
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