Colloidal black gold with broadband absorption for plasmon-assisted crosslinking of thiolated diazonium compound

04 January 2023, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


Broadband light absorbers are very attractive for many applications, including solar energy conversion, photothermal therapy, and plasmonic nanocatalysis. Black gold nanoparticles are an excellent example of broadband light absorbers in the visible and near-infrared (NIR)ranges; however, their synthesis typically requires multi-step deposition and/or high temperatures. Herein, we report the synthesis of black gold via a facile, one-step green method using commonly known precursors (chloroauric acid and sodium citrate) performed at room temperature. The formation of the black gold particles is driven by self-assembly of in-situ formed small nanoparticles (~ 5 nm) followed by a fusion step forming extensive networks of nanowires. These assemblies form intense hotspots for enhancing the electric field as well as the local temperature. Thus, the nanowires exhibit a strong photothermal effect and SERS performance. The high SERS signal enhancement is used to monitor the kinetics of plasmon-assisted de-nitrogenation and cross-linking of designed thiolated benzenediazonium molecules. Analysis of the reaction performed with external heating in dark and under light irradiation confirmed the charge transfer effect (i.e., hot electrons) to be the dominant mechanism. Our work offers new possibility to design efficient light absorbing materials to achieve good solar-to-chemical/thermal energy conversion.


black gold
photothermal effect
plasmon chemistry


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.