Ultrathin semiconducting sheet showing gas-responsive electronic properties for highly sensitive gas sensors

April 14, 2017, King Abdullah University of Science and Technology
Atomistic model showing the charge accumulation (yellow) and depletion (red) upon NO adsorption on PtSe2 monolayer. Platinum atoms appear in gray and selenium atoms are shown in green. Credit: Reproduced with permission from ref 1. © 2016 WILEY-VCH

Gas detectors capable of sensing minute quantities of pollutants could help better monitor air quality. Saudi Arabia's King Abdullah University of Science and Technology (KAUST) researchers have discovered a two-dimensional electronic material that exhibits high sensitivity to gas molecules, such as carbon dioxide (CO2), nitrogen oxides (NOx) and ammonia (NH3).

Atomically thin sheets consisting of transition metals associated with chalcogen atoms, such as sulfur, selenium and tellurium, are versatile alternatives to the more conventional silicon-based semiconductors. Depending on their metal component, these transition metal dichalcogenide monolayers have band gaps—energy barriers that limit electron flow through a material—that can be tuned to alter their .

The unique electronic properties of these monolayers have potential to improve a plethora of devices, including , photodetectors and gas sensors.

Semiconducting monolayers are proven to be ideal candidates as gas sensing materials because they have a high surface-to-volume ratio. For example, MoS2 has been incorporated in field-effect transistors to detect nitrogen monoxide. However, its performance is limited by its relatively low or by the velocity at which its electrons (or holes) move when subjected to an electric field.

To overcome these shortcomings, KAUST Professor Udo Schwingenschlögl's team evaluated the potential of the platinum dichalcogenide PtSe2 for use in via sophisticated computational techniques.

"Monolayer PtSe2 experimentally shows a high carrier mobility, which can be advantageous for gas sensing," said Schwingenschlögl, adding that this material had not previously been considered for this purpose. This approach shows the interaction between monolayer and at both structural and electronic levels.

First, the researchers built a model monolayer composed of selenium atoms that formed octahedral arrangements with one platinum atom at their center. Next, they determined the optimal geometry adopted by individual gas molecules, such as NOx, NH3, H2O, CO2 and CO, upon adsorption. They assessed the capacity of these adsorbed molecules to transfer charge to the monolayer by examining adsorption-induced changes in the electronic properties.

These calculations provided high adsorption energies, indicating strong affinity between monolayer and gas molecules. All adsorbed molecules altered the monolayer charge (see image), which is key for the gas-sensing ability of monolayer PtSe2.

Furthermore, their interactions were more effective with monolayer PtSe2 than its MoS2 or carbon-based graphene analogues. "It was exciting to explain this difference at a molecular orbital level," said Schwingenschlögl. Calculations of electron transport revealed the of PtSe2 as a gas sensor.

Explore further: Ultra-fast, ultra-sensitive PtSe2 gas sensors

More information: Muhammad Sajjad et al. Superior Gas Sensing Properties of Monolayer PtSe, Advanced Materials Interfaces (2017). DOI: 10.1002/admi.201600911

Related Stories

Ultra-fast, ultra-sensitive PtSe2 gas sensors

January 13, 2017

Researchers from Trinity College Dublin, Ireland have shown that PtSe2, a little-studied transition metal dichalcogenide has potential for a variety of uses. In particular, PtSe2 is an excellent high performance gas sensor, ...

Nano-scale electronics score laboratory victory

November 9, 2016

Researchers at the NYU Tandon School of Engineering have pioneered a method for growing an atomic scale electronic material at the highest quality ever reported. In a paper published in Applied Physics Letters, Assistant ...

Team engineers oxide semiconductor just single atom thick

February 8, 2017

A new study, affiliated with UNIST has introduced a novel method for fabrication of world's thinnest oxide semiconductor that is just one atom thick. This may open up new possibilities for thin, transparent, and flexible ...

Recommended for you

Scientists create gold nanoparticles in water

April 19, 2018

An experiment that, by design, was not supposed to turn up anything of note instead produced a "bewildering" surprise, according to the Stanford scientists who made the discovery: a new way of creating gold nanoparticles ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.