Yijiang Liu

Synthesis and photovoltaic properties of polythiophene stars with porphyrin core

Two novel porphyrin-polythiophene star-shaped polymer (P-bs1 and P-bs2) containing triphenylamine terminated poly(3′-hexyl-2,2′-bithiophene) and poly(3′-hexyl-2,2′-bithiophene) as four arms in the peripheral of porphyrin core were synthesized by Stille reaction. The thermal, photophysical, electrochemical and photovoltaic properties of the porphyrin-polythiophene derivatives were investigated. The porphyrin-polythiophene derivatives showed broad absorption in the region of 350 ∼ 650 nm. In particular, the absorption intensity at 450 ∼ 650 nm was greatly enhanced for the meso-substituted polythiophene derivatives, P-bs2. The photoluminescence spectra indicated that the emission peaks of porphyrin units were suppressed by the intensive emission of thiophene units. The electrochemical properties indicated that the porphyrin-polythiophene derivatives are potential electron-donor materials for bulk heterojunction solar cells and dye-sensitized solar cells (DSSCs). Polymer bulk heterojunction solar cells based on P-bs2:PCBM (1:1, w/w) showed power conversion efficiencies (PCE) up to 0.61% under the illumination of AM 1.5, 100 mW cm−2, which increased by 69% compared to that of P-bs1 (0.36%). Meanwhile, higher PCE of 2.17% and 3.91% based on P-bs1 and P-bs2 polymer-sensitized solar cells were attained. The better photovoltaic properties benefited from longer arms of polythiophene derivatives.

Porous N-Doped Carbon Prepared from Triazine-Based Polypyrrole Network: A Highly Efficient Metal-Free Catalyst for Oxygen Reduction Reaction in Alkaline Electrolytes

Metal-free N-doped carbon (NC) materials have been regarded as one of the most promising catalysts for the oxygen reduction reaction (ORR) in alkaline media because of their outstanding ORR catalytic activity, high stability, and good methanol tolerance. Up to now, only a small minority of such catalysts have been synthesized from triazine-based polymeric networks. Herein, we report the synthesis of such NC catalyst by directly pyrolyzing a nitrogen-rich, triazine-based polypyrrole network (TPN). The TPN is fabricated by oxidative polymerization of 2,4,6-tripyrrol-1,3,5-triazine monomer using TfOH as the protonating agent and benzoyl peroxide as the oxidizing agent. The obtained NC-900 (pyrolyzed at 900 °C) catalyst exhibits excellent ORR activity in alkaline media with a high ORR onset potential (0.972 V vs RHE), a large kinetic-limiting current density (15.66 mA cm-2 at 0.60 V), and good MeOH tolerance and durability. The as-synthesized NC-900 material is a potential candidate as a highly active, stable, and low-cost ORR catalyst for alkaline fuel cells.

A Porous Organic Poly(triphenylimidazole) Decorated with Palladium Nanoparticles for the Cyanation of Aryl Iodides

A new porous organic poly(triphenylimidazole), PTPI-Me, was prepared through a Yamamoto self-coupling reaction of 2,4,5-tris-(4-bromophenyl)-1-methyl-1H-imidazole (TPI-Me) in the presence of bis(1,5-cyclooctadiene)nickel(0). The polymer was subsequently decorated with Pd nanoparticles (NPs) to afford a heterogeneous cyanation catalyst, Pd@PTPI-Me. Pd NPs with an average diameter of 2.7 nm were grown within the PTPI-Me framework, owing to the coordination of the imidazole rings to the Pd species. The resultant Pd@PTPI-Me catalyst, with a Pd loading of 0.13 mmol g-1 , exhibited superior catalytic activity for the cyanation of aryl iodides. More importantly, the heterogeneous catalyst was also readily recycled and displayed negligible deactivation after five cycles.