Effect of photocurrent enhancement in porphyrin-graphene covalent hybrids

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• 作者：Jianguo Tang ; Lin Niu ; Jixian Liu ; Yao Wang ; Zhen Huang ; Shiqiang Xie ; Linjun Huang ; Qingsong Xu ; Yuan Wang ; Laurence A. Belfiore
• 关键词：Photocurrent ; Porphyrin ; Graphene ; Hybrid
• 刊名：Materials Science and Engineering: C
• 出版年：1 January, 2014
• 年：2014
• 卷：34
• 期：Complete
• 页码：186-192
• 全文大小：989 K

文摘

Graphene oxide (GO) sheets were covalently functionalized with 5-p-aminophenyl-10,15,20-triphenylporphyrin (NH₂TPP) by an amidation reaction between the amino group in NH₂TPP and carboxyl groups in GO. The Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning and transmission electron microscopies reveal that NH₂TPP covalent bonds form on the double surface of graphene oxide sheets, generating a unique nano-framework, i.e., NH₂TPP-graphene-NH₂TPP. Its UV-visible spectroscopy reveals that the absorption spectrum is not a linear superposition of the spectra of NH₂TPP and graphene oxide, because a 59 nm red shift of the strong graphene oxide absorption is observed from 238 to 297 nm, with significant spectral broadening between 300 and 700 nm. Fluorescence emission spectroscopy indicates efficient quenching of NH₂TPP photoluminescence in this hybrid material, suggesting that photo-induced electron transfer occurs at the interface between NH₂TPP and GO. A reversible on/off photo-current density of 47 mA/cm² is observed when NH₂TPP-graphene-NH₂TPP hybrid sandwiches are subjected to pulsed white-light illumination. Covalently-bound porphyrins decrease the optical HOMO/LUMO band gap of graphene oxide by 鈮?#xA0;1 eV, according to UV-visible spectroscopy. Cyclic voltammetry predicts a small HOMO/LUMO band gap of 0.84 eV for NH₂TPP-graphene-NH₂TPP hybrid sandwiches, which is consistent with efficient electron transfer and fluorescence quenching.