The adsorption behavior of toxic gas molecules (NO, CO, NO 2 , and NH 3 ) on graphene-like BC 3 are investigated using first-principle density functional theory (DFT). The most stable adsorption configurations, adsorption energies, binding distances, charge transfers, electronic band structures, and the conductance modulations are calculated to deeply understand the impacts of the molecules above on the electronic and transport properties of the BC 3 monolayer. The graphene-like BC 3 monolayer is a semiconductor with a band gap of 0.733 eV. The semi-metal graphene has a low sensitivity to the abovementioned molecules. However, it is discovered that all the above gas molecules are chemically adsorbed on the BC 3 sheet with the adsorption energies less than −1 eV. The NO 2 gas molecule is totally dissociated into NO and O species through the adsorption process, while the other gas molecules retain their molecular forms. The amounts of charge transfer upon adsorption of CO and NH 3 gas molecules on BC 3 are found to be small. Hence, the band gap changes in BC 3 as a result of interactions with CO and NH 3 are only 4.63% and 16.7%, indicating that the BC 3 -based sensor has a low and moderate sensitivity to CO and NH 3 , respectively. Contrariwise, upon adsorption of NO or NO 2 on BC 3 , a significant charge is transferred from the molecules to the BC 3 sheet, causing a semiconductor-metal transition. It is found that the BC 3 -based sensor has high potential for NO detection due to the significant conductance changes, moderate adsorption energy, and short recovery time. More excitingly, the BC 3 is a likely catalyst for dissociation of the NO 2 gas molecule. Our findings divulge promising potential of the graphene-like BC 3 as a highly sensitive molecular sensor for NO and NH 3 detection and a catalyst for NO 2 dissociation.

A spectacular SGS character with 100% spin polarized currents around the Fermi level is found in z2–1 functionalized with Cl.

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Surface modification is a reliable method to enhance the sensing properties of pristine graphene by increasing active sites on its surface. Herein, we investigate the interactions of the gas molecules such as NH 3 , NO, NO 2 , H 2 O, and H 2 S with a zinc oxide (ZnO)-graphene hybrid nanostructure. Using first-principles density functional theory (DFT), the effects of gas adsorption on the electronic and transport properties of the sensor are examined. The computations show that the sensitivity of the pristine graphene to the above gas molecules is considerably improved after hybridization with zinc oxide. The sensor shows low sensitivity to the NH 3 and H 2 O because of the hydrogen-bonding interactions between the gas molecules and the sensor. Owing to observable alterations in the conductance, large charge transfer, and high adsorption energy; the sensor possesses extraordinary potential for NO and NO 2 detection. Interestingly, the H 2 S gas is totally dissociated through the adsorption process, and a large number of electrons are transferred from the molecule to the sensor, resulting in a substantial change in the conductance of the sensor. As a result, the ZnO-graphene nanosensor might be an auspicious catalyst for H 2 S dissociation. Our findings open new doors for environment and energy research applications at the nanoscale.

Graphene has been a material of interest due to its versatile properties and wide variety of applications. However, production has been one of the most challenging aspects of graphene and multilayer graphene (MLG). Most synthesis techniques require elevated temperatures and additional steps to transfer graphene or MLG to a substrate, which compromises the integrity of the film. In this paper, metal-induced crystallization is explored to locally synthesize MLG directly on metal films, creating an MLG-metal composite and directly on insulating substrates with a moving resistive nanoheater probe at much lower temperature conditions (~ 250 °C). Raman spectroscopy shows that the resultant carbon structure has properties of MLG. The presented tip-based approach offers a much simpler MLG fabrication solution by eliminating the photolithographic and transfer steps of MLG.

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