Mie University

The design of novel semiconducting photocatalysts is crucial for hydrogen production using sunlight.Covalent organic frameworks (COFs), which are porous materials formed solely by the covalent bonding of light elements, have garnered significant attention as efficient photocatalysts.However, common COFs face challenges related to visible light absorption, the recombination rate of electron-hole pairs, and hydrogen production activity.In this study, we successfully synthesized a 1,3,5-Triformylphloroglucinol (TP) -based hybrid COF {(TP-TTA/TP-TSN)-COF}, using a simple hydrothermal method, incorporating two amine linkers: 4,4′,4′′-(1,3,5-triazine-2,4,6-triyl) trianiline (TTA) and 3,7-diamino-2,8-dimethyldibenzothiophenesulfone (TSN).This hybrid COF exhibits excellent optical and electrochem. properties due to the large electron transport characteristics of the triazine ring and the electron-withdrawing nature of the sulfonic group.It achieved a hydrogen production rate of 2200 μmol g^-1 h^-1, approx. twice that of conventional TP-TTA-COF (980 μmol g^-1 h^-1) and TP-TSN-COF (1100 μmol g^-1 h^-1).This study presents an effective strategy for enhancing the photocatalytic activity of COF-based materials.

The fabrication of heterojunction photocatalysts is important for achieving highly efficient electron transfer, charge separation, and catalytic activity.In this study, we report the successful creation of a type II heterojunction between pyridine incorporated and O-doped g-C₃N₄ (POCN) and a covalent organic framework (COF).The heterojunction formation significantly reduced the fluorescence intensity of the POCN/COF, indicating effective separation of electron-hole pairs.Addnl., POCN/COF demonstrated excellent interface charge transfer resistance and photocurrent response.Its hydrogen production rate was remarkably high at 3500 μmol g^-1 h^-1, about 1.6 times that of pure COF (2200 μmol g^-1 h^-1) and 3.5 times that of the phys. mixture (1000 μmol g^-1 h^-1), and it also exhibited enhanced stability.This indicates that it can be effectively fabricated into a heterojunction of POCN and COF.The optimal value for adding POCN was approx. 5 wt% of COF.This demonstrates greater activity compared to other composite catalysts made from graphitic carbon nitride and COF.This study presents a valuable approach for fabricating reusable heterojunction photocatalytic systems and efficiently generating hydrogen from natural energy sources.

Physicochem. properties of atomically precise metal clusters can be modulated by incorporating different metal atoms.In this article, successful one-pot synthesis of single Au-atom doped chiral AuAg28 clusters protected by water-soluble N-acetyl-(S)-penicillamine (=S-NAP) is reported.The reduction of Ag and Au ions at 0 °C in the presence of S-NAP and triphenylphosphine (TPP) using tetramethylammonium borohydride (TMAB) is crucial.Importantly, upon doping of an Au atom to the monometallic Ag29 cluster, which improves the cluster stability, the chiroptical activity or maximum anisotropy factor of the bimetallic AuAg28 cluster is enhanced as compared to that of the monometallic species, which can be due to an increase in the rotatory strength that is probably brought about by the increased contribution of optical transition associated with helically-arranged surface shell layers.Such chiroptical behaviors suggest that the Au dopant position in the bimetallic cluster is not fluxional but rigid.Then the present results will help design some heteroatom-doped silver clusters with excellent chiroptical properties.