物理化学学报2023，Vol.39Issue(11)：109-119,11.DOI:10.3866/PKU.WHXB202212062
亚甲基蓝嵌入的供体受体型g-C3N4纳米片光催化剂用于产H2
Methylene Blue Incorporated Donor-Acceptor g-C3N4 Nanosheet Photocatalyst for H2 Production
摘要
Abstract
Photocatalytic hydrogen production is a promising strategy for utilizing inexhaustible solar energy as a source of clean energy.Graphitic carbon nitride(g-C3N4)is a widely used photocatalytic material in photocatalytic hydrogen production because of its simple preparation process,suitable band structure,and high stability.However,the low charge carrier separation efficiency and small specific surface area of pristine g-C3N4 restrict its photocatalytic activity.It has been demonstrated that the construction of intramolecular donor-acceptor(D-A)systems and ultra-thin nanosheet structures are effective strategies for enhancing the photocatalytic activity of g-C3N4.Herein,an intramolecular D-A structured g-C3N4 nanosheet photocatalyst is synthesized through the thermal copolymerization of dicyandiamide and methylene blue(MB),followed by thermal exfoliation.X-ray diffraction,Fourier transform infrared spectrometry,solid-state 13C nuclear magnetic resonance,and X-ray photoelectron spectroscopy analyses reveal that MB is successfully incorporated into the g-C3N4 framework and well retained after thermal exfoliation.The resulting D-A system induces intramolecular charge transfer from the donor units(MB segment)to the acceptor units(tri-s-triazine rings)and extends the absorption edge to approximately 500 nm.The ultra-thin nanosheet structure produced by thermal exfoliation shortens the charge transfer distance from the interior to the surface of g-C3N4 and reduces the charge transfer resistance,which increases the charge carrier separation efficiency.Furthermore,the introduction of MB generates a flaky structure during copolymerization,which promotes thermal exfoliation and results in a remarkably increased specific surface area.The transient photocurrent response,electrochemical impedance spectra,and time-resolved photoluminescence decay spectra reveal that the charge transfer and separation of g-C3N4 are further promoted by integrating the intramolecular D-A system and ultra-thin nanosheet structure.Density functional theory calculations further demonstrate that MB donates electrons to tri-s-triazine rings(electron acceptor).Moreover,the highest occupied molecular orbit of D-A structured g-C3N4 is mostly distributed around the MB segment,while the lowest unoccupied molecular orbit is distributed around tri-s-triazine rings,resulting in spatially separated photogenerated electron-hole pairs.Through integrating the intramolecular D-A system and ultra-thin nanosheet structure,the obtained photocatalyst exhibits enhanced charge carrier separation,an extended absorption edge,and enlarged specific surface area.As a consequence,the D-A structured g-C3N4 nanosheet shows a considerably improved photocatalytic hydrogen production activity(2275.6 μmol·h-1·g-1),which is 5.30,2.60,and 1.30 times that of bulk g-C3N4,D-A structured bulk g-C3N4,and g-C3N4 nanosheet,respectively.This work offers a valuable strategy for developing D-A-modified photocatalytic materials for solar energy conversion.关键词
供体-受体/亚甲基蓝/g-C3N4纳米片/光催化产氢Key words
Donor-acceptor/Methylene blue/g-C3N4 nanosheet/Photocatalytic hydrogen production分类
化学引用本文复制引用
殷方鑫,秦品权,许景三,曹少文..亚甲基蓝嵌入的供体受体型g-C3N4纳米片光催化剂用于产H2[J].物理化学学报,2023,39(11):109-119,11.基金项目
国家重点研发计划(2022YFE0114800)与国家自然科学基金(51922081)资助项目 The project was supported by the National Key R&D Program of China(2022YFE0114800)and the National Natural Science Foundation of China(51922081). （2022YFE0114800）
