With sunlight or blue LEDs irradiation, regioselective decarboxylative alkylation of various non‐aromatic heterocycles has been realized via C(sp3)‐centered radical C(sp2)−C(sp3) bond formation under ...oxidant‐free conditions at room temperature. This reaction readily incorporates various functional alkyl groups into heterocyclic compounds without observation of any alkyl radical rearrangement and represents a mild and general tool for the preparation of valuable alkyl group‐functionalized heterocyclic compounds.
Photoelectrochemical (PEC) water splitting into hydrogen and oxygen is a promising solution for the conversion and storage of solar energy. Because sluggish water oxidation is the bottleneck of water ...splitting, the design and preparation of an efficient photoanode is intensively investigated. Currently, all known photoanode materials suffer from at least one of the following drawbacks: ① low carriers separation efficiency; ② sluggish surface water oxidation reaction; ③ poor long‐term stability; ④ insufficient water adsorption and gas desorption. Core–shell configurations can endow a photoanode with improved activity and stability by coating an overlayer that plays energetic, catalytic, and/or protective roles. The construction strategy has an important effect on the activity of a core–shell photoanode. Nonetheless, the mechanism for the improvement of performance is still ambiguous and is worthy of a closer examination. In this review, the successes and challenges of core–shell photoanodes for water oxidation, focusing on synthesis strategies as well as functionalities (facilitating carrier separation, surface reaction promotion, corrosion prevention, and bubble detachment) are explored. Finally, the perspectives of this class of materials in terms of new opportunities and efforts are discussed.
Core–shell configurations, constructed via photo/electrodeposition, atomic layer deposition, chemical vapor deposition, ligand‐assisted strategy or ion exchange strategy, endow photoanodes with improved activity and stability by optimizing and facilitating carrier separation, surface reaction promotion, corrosion prevention, and bubble detachment process during photoelectrochemical water oxidation.
The introduction of oxygen vacancies (Ov) has been regarded as an effective method to enhance the catalytic performance of photoanodes in oxygen evolution reaction (OER). However, their stability ...under highly oxidizing environment is questionable but was rarely studied. Herein, NiFe‐metal–organic framework (NiFe‐MOFs) was conformally coated on oxygen‐vacancy‐rich BiVO4 (Ov‐BiVO4) as the protective layer and cocatalyst, forming a core–shell structure with caffeic acid as bridging agent. The as‐synthesized Ov‐BiVO4@NiFe‐MOFs exhibits enhanced stability and a remarkable photocurrent density of 5.3±0.15 mA cm−2 at 1.23 V (vs. RHE). The reduced coordination number of Ni(Fe)‐O and elevated valence state of Ni(Fe) in NiFe‐MOFs layer greatly bolster OER, and the shifting of oxygen evolution sites from Ov‐BiVO4 to NiFe‐MOFs promotes Ov stabilization. Ovs can be effectively preserved by the coating of a thin NiFe‐MOFs layer, leading to a photoanode of enhanced photocurrent and stability.
A core–shell Ov‐BiVO4@NiFe‐MOFs photoanode was constructed via a coordination‐assisted self‐assembly method. A NiFe‐MOFs thin layer acts as protective layer and cocatalyst to shift active sites from oxygen vacancies to NiFe‐MOFs, leading to improved stability and activity for OER. This molecular‐based approach tailors the coordination and electronic structure of active sites and provides mechanistic insights for rational design of photocatalysts.
CdS nanowires decorated with ultrathin MoS2 nanosheets were synthesized for the first time by ultrasonic exfoliation by using dimethylformamide as the dispersing agent. An excellent hydrogen ...evolution rate of 1914 μmol h−1 (20 mg catalyst) under visible‐light irradiation (λ≥400 nm, ≈154 mW cm−1) and an apparent quantum yield of 46.9 % at λ=420 nm were achieved over the MoS2/CdS composite. The presence of ultrathin MoS2 nanosheets (rich in active edge sites) on the CdS surface promotes the separation of photogenerated charge carriers and facilitates the surface processes of photocatalytic hydrogen evolution.
Down to the wire: A composite comprising CdS nanowires decorated with ultrathin MoS2 nanosheets is synthesized by an ultrasonic exfoliation method using dimethylformamide as a dispersing agent. The composite shows high photocatalytic efficiency for hydrogen evolution.
Metal‐organic framework (MOF) is an ideal precursor/template for porous carbon, and its active components are uniformly doped, which can be used in energy storage and catalytic conversion fields. ...Metal‐organic framework PCN‐224 with carboxylporphyrin as the ligand was synthesized, and then Zn2+ and Co2+ ions were coordinated in the center of the porphyrin ring by post‐modification. Here, PCN‐224−ZnCo with different ratios of bimetallic Zn2+/Co2+ ions were used as the precursor, and the metal‐nitrogen‐carbon(M−N−C) material of PCN‐224−ZnCo‐950 was obtained by pyrolyzing the precursor at 950 °C in Ar. Because Zn is easy to volatilize at 950 °C, the formed M−N−C materials can reflect different Co contents and different basic site concentrations. The formed material still maintains the original basic framework. With the increase of Zn2+/Co2+ ratio in precursor, the concentration of N‐containing alkaline sites in pyrolysis products gradually increase. Compared with the precursor, PCN‐224−ZnCo1‐950 with Zn2+/Co2+=1 : 1 has greatly improved basicity and suitable acidic/ alkaline site concentration. It can be efficiently used to carbon dioxide absorption and catalyze the cycloaddition of CO2 with epoxide. More importantly, the current method of adjusting the acidic/basic sites in M−N−C materials through volatilization of volatile metals can provide an effective strategy for adjusting the catalysis of MOF derivatives with porphyrin structure.
PCN‐244−ZnCo1 was successfully synthesized and then pyrolyzed to the target product PCN‐224−ZnCo1‐950 at 950 °C. The physical structure of PCN‐224−ZnCo1‐950 did not change much, as judged by SEM and N2 adsorption and desorption. Due to the volatilization of Zn, PCN‐224−ZnCo1‐950 has greatly improved basicity and suitable acidic/alkaline site concentration compared to the precursor. It can be efficiently used to carbon dioxide absorption and catalyze the cycloaddition of CO2 with epoxides.
Sulfur‐containing 1,2,3‐triazoles display bioactivities like antidepressant, antifungal activity, antitumor, etc. Numerous approaches have been established to form sulfur‐containing 1,2,3‐triazoles. ...4‐Sulfanyl‐ and 5‐sulfanyl‐1,2,3‐triazoles were produced by metal‐catalyzed azide‐alkyne cycloaddition (AAC), etc. N‐Sulfonyl‐1,2,3‐triazoles were generated via the reaction of acetylides with sulfonyl azides, CuAAC. 4‐Sulfonyl‐1,2,3‐triazoles were produced through 3+2 cycloaddition and reaction of azide with bromovinylsulfonyl fluoride. Although 5‐sulfonyl‐1,2,3‐triazoles were formed successfully via RuAAC, their synthetic approaches were very limited. 1‐Phosphinyl‐2‐sulfanylethynes were suitable substances to access sulfur‐ and phosphorus‐containing triazoles. In this review, the synthesis and properties of sulfur‐containing 1,2,3‐triazoles were highlighted. Initially, the properties of organosulfurs, 1,2,3‐triazoles and sulfur‐containing 1,2,3‐triazoles were briefly introduced. After stating the general procedures to construct 1,2,3‐triazole skeleton, the synthetic approaches and properties of sulfur‐involved 1,2,3‐triazoles were sorted and described in details. According to different kinds of sulfur‐containing 1,2,3‐triazoles, synthetic methods and features of 4‐sulfanyl‐1,2,3‐triazoles, 5‐sulfanyl‐1,2,3‐triazoles, N‐sulfonyl‐1,2,3‐triazoles, 4‐sulfonyl‐1,2,3‐triazoles, 5‐sulfonyl‐1,2,3‐triazoles, sulfur‐ and heteroatom‐containing 1,2,3‐triazoles were summarized.
Sulfur‐containing 1,2,3‐triazoles display bioactivities. Numerous approaches have been established to form sulfur‐containing 1,2,3‐triazoles. In this review, the synthesis and properties of sulfur‐containing 1,2,3‐triazoles, including 4‐sulfanyl‐1,2,3‐triazoles, 5‐sulfanyl‐1,2,3‐triazoles, N‐sulfonyl‐1,2,3‐triazoles, 4‐sulfonyl‐1,2,3‐triazoles, 5‐sulfonyl‐1,2,3‐triazoles, sulfur‐ and heteroatom‐containing 1,2,3‐triazoles, were highlighted.
Benzoxazoles extensively exist in biologically active compounds, natural products, pharmaceuticals and functional materials. Thus, facile and green synthesis of such valuable compounds from easily ...available substrates will make a contribution to drug, material, and fine chemistry. A method for the synthesis of benzoxazoles from catechols, aldehydes and ammonium acetate is developed using NaIO4 as oxidant under metal‐ and additive‐free conditions. A broad range of benzoxazoles including some fluorescent whitening agents, JTP‐426467 and tafamidis analogues are synthesized in 56–95% yields with outstanding functional group tolerance. Mechanistic investigations suggest that an interesting o‐iminocyclohexa‐diene alcohol intermediate is involved in the reaction. These salient features of the protocol make it an alternative for the synthesis of benzoxazoles.
A Cu-catalyzed selective aerobic heterocoupling of terminal alkynes is disclosed, which enables the synthesis of a broad range of unsymmetrical 1,3-diynes in good to excellent yields. The results ...disprove the long-held belief that homocouplings are exclusively favored in the Glaser–Hay reaction.
Display omitted
•Cu2O/BiVO4 photocatalyst was synthesized under mild conditions.•It shows high catalytic activity for the simultaneous removal of dyes and Cr(VI).•The degradations of cationic and/or ...anionic dyes operate under neutral condition.•A synergistic photoreduction–oxidation mechanism is proposed.
We synthesized Cu2O/BiVO4 composites by growing Cu2O nanoparticles on BiVO4 under mild condition. The optimized composite shows high photocatalytic efficiency in the simultaneous oxidation of organic dyes and reduction of Cr(VI) in neutral media. The XPS results confirm that the Cr(VI) adsorbed on Cu2O/BiVO4 was completely reduced to Cr(III). The photocatalyst can be used for the degradation of cationic or anionic dyes as well as a mixture of them under visible light irradiation. The photocatalytic activity of the composite can be ascribed to the heterojunctions between Cu2O and BiVO4, which facilitate the separation of photogenerated electrons and holes. The work demonstrates that the as-synthesized Cu2O/BiVO4 composite is a promising photocatalyst for the treatment of wastewater that contains organic dyes and Cr(VI) ions.
Nickel-catalyzed thiolation of the inactivated methyl C(sp3)–H bonds of aliphatic amides with disulfide is described. It is a novel strategy for the synthesis of thioethers with the ultimate goal of ...generating thioether carboxylic acids with various functional groups.
PDF
