The image depicts a schematic of platinum atoms deposited on the surface of the carbon “buffer-layer”. The buffer layer, grown epitaxially on silicon carbide, is a graphene-like 2D insulating material that enables the two-dimensional growth mode of platinum. The chemical-to-electrical transduction with atomically-thin platinum is possible due to inherent interactions of transition metals with chemical analytes, and the fact that platinum is prepared in ultra-thin form (i.e. 2D), such that the resistance of the bulk-less metal is strongly dominated by interactions with chemical species. Illustration: Hans He
Researchers at Chalmers University of Technology in Sweden, with collaborators, have reported the possibility to prepare one-atom thin platinum and use it as chemical sensors. The results were recently published in the scientific journal Advanced Material Interfaces.
“In a nutshell, we managed to make a one-atom thin metal layer, a sort of a new material. We found that this atomically-thin metal is super sensitive to its chemical environment: its electrical resistance changes significantly when it interacts with gases”, explains Kyung Ho Kim, postdoc at the Quantum Device Physics Laboratory at the Department of Microtechnology and Nanoscience – MC2, and lead author of the article.
The spirit of the research is the development of 2D materials beyond graphene.
“Atomically thin platinum can be actually useful for ultra-sensitive and fast electrical detection of chemicals. We have studied the case of platinum in great detail, but other metals like Palladium produce similar results”, says Samuel Lara Avila (below to the right), Associate Professor at the Quantum Device Physics Laboratory at MC2, and one of the authors of the article.
The researchers used the sensitive chemical-to-electrical transduction capability of atomically thin platinum to detect part-per-billion contents of toxic gases. They demonstrate this for detection of benzene, a compound that is cancerogenic to very small concentrations in ambient, and for which no low-cost detection apparatus exists.
“This new material approach, atomically thin metals, is very promising for future air-quality monitoring applications”, says Jens Eriksson, Head of the Applied sensor science unit at Linköping University and co-author of the paper.
Boosting the sensitivity of solid‐state gas sensors by incorporating nanostructured materials as the active sensing element can be complicated by interfacial effects. Interfaces at nanoparticles, grains, or contacts may result in nonlinear current–voltage response, high electrical resistance, and ultimately, electric noise that limits the sensor read‐out. This work reports the possibility to prepare nominally one atom thin, electrically continuous platinum layers by physical vapor deposition on the carbon zero layer (also known as the buffer layer) grown epitaxially on silicon carbide. With a 3–4 Å thin Pt layer, the electrical conductivity of the metal is strongly modulated when interacting with chemical analytes, due to charges being transferred to/from Pt. The strong interaction with chemical species, together with the scalability of the material, enables the fabrication of chemiresistor devices for electrical read‐out of chemical species with sub part‐per‐billion (ppb) detection limits. The 2D system formed by atomically thin Pt on the carbon zero layer on SiC opens up a route for resilient and high sensitivity chemical detection and can be the path for designing new heterogenous catalysts with superior activity and selectivity.
The study is a collaboration between scientists from Chalmers, Linköping University, Uppsala University, University of Zaragoza (Spain), and the beamline MAXPEEM at MAX IV. From Chalmers, Kyung Ho Kim, Hans He and Sergey Kubatkin contributed to the research together with Samuel Lara-Avila.
The work was jointly supported by the Swedish Foundation for Strategic Research (SSF), the Knut and Alice Wallenberg Foundation, The Swedish Research Council and Chalmers Excellence Initiative Nano. The experiments were performed in part at the Nanofabrication Laboratory at Chalmers.
Text courtesy of Michael Nystås, Chalmers
Illustration: Hans He, Chalmers
Read the article here
Kyung Ho Kim, Hans He, Marius Rodner, Rositsa Yakimova, Karin Larsson, Marten Piantek,
David Serrate, Alexei Zakharov, Sergey Kubatkin, Jens Eriksson, and Samuel Lara-Avila
Advanced Materials Interfaces, 2020, Vol. 7 Issue 12