Search Results (4)

Photocatalytic technology offers significant potential for pollutant remediation through efficient, cost-effective mineralization but faces inherent limitations, including catalyst agglomeration and rapid charge recombination. To address these challenges, we developed activated carbon-modified porous graphitic carbon nitride (APCN) synthesized through the co-polycondensation of dicyandiamide with NH₄Cl and fir-wood-derived activated carbon (AC). The incorporated AC effectively prevented the agglomeration of carbon nitride frameworks, thereby enhancing the specific surface area (S_BET) of APCN. This matrix was subsequently composited with hydrothermally prepared (1T/2H) mixed-phase MoS₂ through ultrasonication, forming a MoS₂/APCN heterostructure. Characterizations including Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and N₂ adsorption–desorption isotherms (BET) confirmed that MoS₂ was successfully loaded onto APCN via an ultrasonic synthesis method. The composite exhibited outstanding photocatalytic activity, degrading 95.5% RhB in 40 min (pH = 7) and 97.4% in 25 min (pH = 3.5), with 87.3% efficiency retention after four cycles (pH = 7). Crucially, AC enhanced visible-light absorption and functioned as an electron-mediating component. Photoelectrochemical analyses and radical-trapping experiments confirmed a direct Z-scheme charge transfer mechanism, wherein conductive AC accelerates electron transport and suppresses carrier recombination. This study establishes both an efficient RhB degradation photocatalyst and a sustainable strategy for valorizing agricultural waste in advanced material design. Full article

Herein, we report the Suzuki–Miyaura catalyst-transfer polycondensation (SCTP) of triolborate-type carbazole monomers, i.e., potassium 3-(6-bromo-9-(2-octyldodecyl)-9H-carbazole-2-yl)triolborate (M1) and potassium 2-(7-bromo-9-(2-octyldodecyl)-9H-carbazole-2-yl) triolborate (M2), as an efficient and versatile approach for precisely synthesizing poly[9-(2-octyldodecyl)-3,6-carbazole] (3,6-PCz) and poly[9-(2-octyldodecyl)-2,7-carbazole] (2,7-PCz), respectively. The SCTP of triolborate-type carbazole monomers was performed in a mixture of THF/H₂O using an initiating system consisted of 4-iodobenzyl alcohol, Pd₂(dba)₃•CHCl₃, and t-Bu₃P. In the SCTP of M1, cyclic by-product formation was confirmed, as reported for the corresponding pinacolboronate-type monomer. By optimizing the reaction temperature and reaction time, we successfully synthesized linear end-functionalized 3,6-PCz for the first time. The SCTP of M2 proceeded with almost no side reaction, yielding 2,7-PCz with a functional initiator residue at the α-chain end. Kinetic and block copolymerization experiments demonstrated that the SCTP of M2 proceeded in a chain-growth and controlled/living polymerization manner. This is a novel study on the synthesis of 2,7-PCz via SCTP. By taking advantage of the well-controlled nature of this polymerization system, we demonstrated the synthesis of high-molecular-weight 2,7-PCzs (M_n = 5–38 kg mol⁻¹) with a relatively narrow Ð_M (1.35–1.48). Furthermore, we successfully synthesized fluorene/carbazole copolymers as well as 2,7-PCz-containing diblock copolymers, demonstrating the versatility of the present polymerization system as a novel synthetic strategy for well-defined polycarbazole-based materials. Full article

The present study demonstrates the fabrication of a conjugated porous polymer (CPP-P2) through a Pd-catalyzed Suzuki–Miyaura poly-condensation reaction. ¹³C cross-polarization solid-state NMR and Fourier transform infrared (FTIR) spectroscopy were used to characterize CPP-P2. Pristine nitrogen-containing CPP was explored as a catalyst for the oxygen reduction reaction in 0.1 M KOH aqueous alkaline media. In the case of CPP-P2,the polymer oxygen reduction reaction occurs via a four-electron transfer mechanism. An understanding of the oxygen reduction at the molecular level and the role of molecular packing in the three-dimensional structure was proposed based on density functional theory (DFT) modeling. Full article

Intramolecular transfer of t-Bu₃P-ligated Pd catalyst on a carbon–carbon triple bond (C≡C) and nitrogen–nitrogen double bond (N=N) was investigated and compared with the case of a carbon–carbon double bond (C=C), which is resistant to intramolecular transfer of the Pd catalyst. Suzuki–Miyaura coupling reaction of equimolar 4,4’-dibromotolan (1a) or 4,4’-dibromoazobenzene (1b) with 3-isobutoxyphenylboronic acid (2) was carried out in the presence of t-Bu₃P-ligated Pd precatalyst 3 and KOH/18-crown-6 as a base at room temperature. In both cases, the diphenyl-substituted product was selectively obtained, indicating that the Pd catalyst walked from one benzene ring to the other through the C≡C or N=N bond after the first substitution with 2. Taking advantage of this finding, we conducted unstoichiometric Suzuki–Miyaura polycondensation of 1.3 equiv. of 1 and 1.0 equiv. of phenylenediboronic acid (ester) 6 in the presence of 3 and CsF/18-crown-6 as a base, obtaining high-molecular-weight conjugated polymer with a boronic acid (ester) moiety at both ends, contrary to the Flory principle. Full article