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Novel Porous Boron Nitride Nanosheet with Carbon Doping: Potential Metal-Free Photocatalyst for Visible-Light-Driven Overall Water Splitting
摘要： The band gap of hexagonal boron nitride (h-BN) is far too wide for efficiently utilizing visible light, limiting its application in photocatalysis. The present study employs first principles calculations to demonstrate that the band gap energies of porous h-BN (p-BN) can be tuned by carbon doping to levels appropriate for the absorption of visible-light, and that the conduction band and valence band match well with the potentials of both hydrogen and oxygen evolution reactions. Importantly, a strategy of carbon doping to improve the energy level of valence band maximum is also proposed. Moreover, the carbon-doped p-BN exhibits good separation between photogenerated electrons/holes and structural stability at high temperatures. The DFT results help the design of high-performance two-dimensional photocatalysts that avoid the use of metals.
关键词： metal-free catalysts,photocatalyst,porous boron nitride nanosheets,overall water splitting,band structure engineering
更新于2025-09-23 15:22:29
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Polythioethers with Controlled ?±,??a??End Groups Prepared by Visible Light Induced Thiola??Ene Click Polymerization of Dithiol and Divinyl Ether with 4a??( <i>N</i> , <i>N</i> a??diphenylamino)benzaldehyde as Organocatalyst
摘要： This study reports a step-growth click-polymerization of 1,4-benzenedimethane (BDMT) and diethylene glycol divinyl ether (DEGVE) with 4-(N,N-diphenylamino)-benzaldehyde (DPAB) as a photoredox catalyst under irradiation of visible light. DPAB exhibits a strong UV–vis absorption at 350 nm and a strong fluorescence emission at 480 nm in anisole. There is a strong fluorescence quenching between BDMT and DPAB. The molecular weight of the polythiolether can be controlled by reaction time and monomer feed ratios. More importantly, α,ω-dithiol and α,ω-divinyl telechelic polythiolether oligomers are successfully synthesized by simply changing the molar ratios of BDMT to DEGVE. 1H NMR and MALDI-TOF MS spectra demonstrate that the oligomers have high end group fidelity. In addition, strong fluorescence is observed when the α,ω-dithiol terminated polythiolether adds with N-(1-pyrenyl) maleimide, indicating that the as-prepared polythiolether bears reactive thiol end groups. Furthermore, high molecular weight polythiolether are prepared by chain extension with reactive polythiolether oligomers as macro-monomers. For example, α,ω-divinyl oligomer (Mn = 2000 g mol?1) could further react with α,ω-dithiol oligomer (Mn = 2400 g mol?1) to form high molecular weight polythiolether (Mn = 6000 g mol?1).
关键词： metal-free catalysts,thiol–ene click polymerization,photoredox catalysts,telechelic polymers,photopolymerization
更新于2025-09-19 17:13:59