STM 14

Functionalization of three-dimensional graphene with metal nanoparticles

Three-dimensional epitaxial graphene (3DG), despite being a recent development, has been already demonstrated to be a promising candidate for applications in various fields. Its unprecedented capability of storing hydrogen has been observed and analyzed, as well as its performance in sensing devices.

To enhance the performance of pristine 3DG, the functionalization of 3DG with metals is an option. Thus, we studied the most effective method for producing metal-functionalized 3DG. Our optimized functionalization technique relies on the immersion of the 3DG in a colloidal solution of metal nanoparticles.

We investigated several factors which could impact the effectiveness of functionalization, including immersion time, immersion conditions (static or under ultrasonication), nanoparticle dimensions, and graphene quality. Our results indicate that the optimal functionalization is achieved by using high quality graphene, by immersing the 3DG samples for 24 hours in static conditions. The nanoparticle dimensions are also critical, as smaller nanoparticles diffuse more easily into the pores. This method allowed us to successfully functionalize 3DG with Gold and Palladium nanoparticles. Figure 1 shows SEM images of Au- and Pd-functionalized 3DG samples.


Figure 1: (a) Top-view SEM image of an Au nanoparticle-functionalized 3DG sample. The scale bar indicates 500 nm. (b) Top-view SEM image of a Pd nanoparticle-functionalized 3DG sample. The scale bar indicates 200 nm.

Through STEM and SEM measurements, we were able to determine the nanoparticle density both on the top-surface and inside the porous structure of 3DG. Au-functionalized 3DG samples exhibited nanoparticle densities of hundreds of nanoparticles per μm^2 on the top-surface and tens of nanoparticles per μm2 inside the porous structure. The nanoparticle densities obtained in Pd-functionalized samples are more than one order of magnitude higher compared to gold, both on the top-surface and inside the pores. This is a consequence of the smaller dimension of the Pd nanoparticles.

XPS analysis confirmed that the functionalization process is “clean,” with no contamination detected on the functionalized samples. Furthermore, XPS measurements demonstrated that 3DG functionalized with both Au and Pd remains thermally stable up to at least 530 °C.

In conclusion, we have developed a reliable and cost-effective method for functionalizing 3DG with metal nanoparticles, which will allow to further widen the range of applicability and the performance of this material.

Publications:

  1. Emanuele Pompei: Functionalization of 3D Graphene with Metal Nanoparticles: Perspectives for Hydrogen Storage, Master Thesis, University of Pisa, Italy. [pdf file]
  2. Emanuele Pompei, Ylea Vlamidis, Letizia Ferbel, Valentina Zannier, Silvia Rubini, Daniel Arenas Esteban, Sara Bals, Carmela Marinelli, Georg Pfusterschmied, Markus Leitgeb, Ulrich Schmid, Stefan Heun, Stefano Veronesi: Metal Nanoparticle-Functionalized Three-Dimensional Graphene: a versatile platform towards sensors and energy-related applications, arXiv:2310.16797 [physics.app-ph].

Presented at:

  1. Emanuele Pompei: Functionalization of 3D Graphene with Metal Nanoparticles: Perspectives for Hydrogen Storage, Master Thesis defense, University of Pisa, Italy, 06 June 2023. [Abstract] [Talk]
  2. S. Heun: Hydrogen Storage in Graphene, Karl-Franzens-Universität Graz, Austria (Dr. Donato Civita/Prof. Leonhard Grill), 17 March 2023. [Abstract] [Talk]
  3. S. Heun: Prospects for Hydrogen Storage in Graphene, Montanuniversität Leoben, Austria (Prof. Christian Teichert), 20 March 2023. [Abstract] [Talk]
  4. Stefano Veronesi, Aureliano Macili, Ylea Vlamidis, Emanuele Pompei, Georg Pfusterschmied, Markus Leitgeb, Ulrich Schmid, Stefan Heun: Hydrogen absorption in a novel three-dimensional graphene structure: Towards hydrogen storage applications, CMD 30 Fismat 2023, Milan, Italy, September 4 – 8, 2023. [Abstract] [Talk]
  5. Stefan Heun: Prospects for Hydrogen Storage in Graphene, Kwansei Gakuin University, Sanda, Hyogo, Japan (Prof. H. Hibino), 2 October 2023. [Abstract] [Talk]