A new study from the University of Nebraska-Lincoln said: The attachment of similar DNA-shaped ribbons to gas sensors can increase the sensitivity of their sensing, far superior to all known carbon materials.
The team developed a new form of nanoribbons made from graphene, where the graphene structure is a two-dimensional honeycomb of carbon atoms. When the researchers integrated the nanobelt film into the gas sensor circuit, the sensor with the nanoribbon film exhibited approximately 100 percent higher response to the molecule than the original sensor (even the best performance carbon-based material). Times.
Alexander Sinitskii, an associate professor of chemistry at Nebraska, said: Previously, sensors based on other carbon-based materials such as graphene and graphene oxide have been studied. In the graphene nanoribbon-based sensor test, we guessed that the response of the sensor would be observed, but unexpectedly it was more sensitive than ever before.
Researchers published in the journal Nature Communications believe that gas molecules can significantly change the resistance of nanobelt films. Different gases have unique resistance characteristics, which allows the sensor to distinguish between different gases.
Sinitskii, a member of the Center for Materials and Nanosciences in Nebraska, said: "There are multiple sensors on the chip that are sufficient to distinguish between molecules that have almost the same chemical properties, such as methanol and ethanol. Thus, sensors based on graphene nanoribbons are not only sensitive. High and selective."
The renderings shown show that the gas molecules enlarge the spacing between the graphene nanoribbons. Alexander Sinitskii and colleagues in Nebraska stated that this phenomenon explains to some extent how nanoribbons provide an unprecedented increase in sensor sensitivity.
Sinitskii and colleagues predict that the extraordinary properties of nanoribbons are partly due to unusual interactions between nanoribbons and gas molecules. Unlike the previous graphene experimental materials, the team's nanoribbon arrangement resembles Charlie Brown's shirt stripe, which vertically displaces the horizontal distribution. The team proposes that gas molecules can separate these stripes, effectively extending the nanoband gap, and electrons must skip these stripes to conduct electricity.
Benzene ring entry
Graphene was discovered in 2004 and won the Nobel Prize for its unparalleled electrical conductivity. However, given the lack of band gaps in graphene materials (band gaps require that the electrons gain energy before they jump from the orbit near the atoms to the external "conducting band"), researchers are unable to control the size of their conductivity. This is precisely a challenge for graphene applications (electronics fields that require adjustment of material conductivity).
The potential solution is to trim sheetlike graphene into nanoscale ribbons and computer simulations to create an elusive bandgap. This proves that the difficult-to-retain properties of graphene are closely related to the precision of its required atoms, so researchers have begun to make ribbons by specifically focusing the molecules on a specific type of solid surface from the bottom up. Although this process works and the resulting band does have a band gap, this process limits the researchers to making only a few ribbons at a time.
In 2014, Sinitskii pioneered a method for the large-scale production of nanobelts in solution, which is a key step in the expansion of electronic applications. However, these nanobelt films made in solution have poor electrical conductivity and are difficult to measure electronically. The team's latest research adapts the original chemistry by adding benzene rings (cyclic molecules with six carbon atoms and hydrogen atoms) on either side of the first-generation nanoribbons. These benzene rings broaden the ribbon, reduce the bandgap, and increase the conductivity of the nanoribbon film.
Sinitskii said: "People usually do not use graphene nanoribbons as sensing materials. However, materials with similar properties to nanometers such as transistors (with the ability to increase the electrical conductivity by several orders of magnitude) are also suitable for sensors. in".
At present, many different kinds of graphene nanoribbons with different characteristics can be designed. So far, only a few types have been proved by experiments. However, there are many interesting theoretical hypotheses for those nanoribbons that have not yet been synthesized, so new nanoribbons are likely to have better sensor characteristics.
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