Acta Chimica Sinica ›› 2020, Vol. 78 ›› Issue (7): 675-679.DOI: 10.6023/A20050145 Previous Articles     Next Articles



朱青青, 宋晓君, 邓兆祥   

  1. 中国科学技术大学化学系 中科院软物质化学重点实验室 合肥微尺度物质科学国家研究中心 合肥 230026
  • 投稿日期:2020-05-19 发布日期:2020-08-06
  • 通讯作者: 邓兆祥
  • 基金资助:

Tunable Charge Transfer Plasmon at Gold/Copper Heterointerface

Zhu Qingqing, Song Xiaojun, Deng Zhaoxiang   

  1. CAS Key Laboratory of Soft Matter Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
  • Received:2020-05-19 Published:2020-08-06
  • Supported by:
    Project supported by the National Key Research and Development Program of China (Nos. 2016YFA0201300, 2018YFA0702001) and the National Natural Science Foundation of China (Nos. 21425521, 21972130, 21521001).

Metal nanostructures with localized surface plasmon resonance (LSPR) have attracted great attention in catalysis, sensing, nanooptics, and nanomedicine. Charge transfer plasmon (CTP) is a LSPR mode that strongly depends on a conductive junction between metallic nanounits. Benefitting from the charge transfer junction, CTP provides a facile way to generate widely tunable LSPR with highly localized/enhanced light magnetic field and photothermal effect. The limited availability of highly tunable CTP structures and their fabrication techniques hinders a further pursuit of their functions and applications. In response to this situation, the present work aims at developing a simple while highly efficient synthetic route to width-adjustable Au/Cu heterojunctions capable of evoking tunable CTP behaviors. The strategy relies on a non-specific surface adsorption of low-cost, naturally occurred fish sperm DNA on a gold nanoseed to control heterogeneous copper nucleation. Such a process offers a chance to tailor the contact area between the gold and copper nano-domains in the bimetallic structure. Highly tunable CTP resonance from visible to near-infrared region is then realizable on the basis of this method. Experimental and calculated extinction spectra consistently reveal three key variables for the CTP structure, including the width of conductive junction and the sizes of gold and copper particles. These parameters are associated with DNA coverage, copper precursor concentration, and the synthetic conditions for gold nanoparticles, which allow for a CTP tuning from visible to near infrared wavelengths. By fully exploiting these highly controllable parameters, the maximally achievable CTP wavelength readily enters a near infrared Ⅱ domain. The resulting CTP signals have a red-shift of up to 750 nm relative to the 530~570 nm LSPR peaks of individual gold and copper nanoparticles, corresponding to a very narrow Au/Cu conductive contact of 11~13 nm in width. The role of nonspecific DNA adsorption in the above process proves unique (currently irreplaceable) compared to other molecular adsorbates. The easily tunable Au/Cu heterointerface paves a way to integrated CTP and catalytic/sensing functions in future research.

Key words: charge transfer, interface, metal, dimerization, DNA