Theoretical Study On Several Low-dimensional Nanomaterials In Gas Sensing And Drug Delivery

In recent years,low-dimensional nanomaterials have attracted extensive attention due to their extraordinary performance in various application fields.Low-dimensional nanomaterials have a wide range of applications in multiple directions such as gas sensors,drug delivery,and catalysis due to their nanometer size and high specific surface area.In this work,three low-dimensional nanomaterials(C₂₄N₂₄ fullerene,borophene and boron nitride fullerenes nanostructures)were chosen to investigate their applications in gas sensing and drug delivery,respectively.A number of studies have also shown that boron nitride fullerenes nanostructures readily penetrates cellular barriers and is chemically stable and noncytotoxic in humans.They can combine with drugs with appropriate adsorption strength and deliver them to cancer tissues,and the drug molecules will be released at the cancer cells and play a role.However,the adsorption of gas molecules on pristine C₂₄N₂₄ and borophene are relatively weak and not suitable as gas sensors.Therefore,it is necessary to functionalize these two low-dimensional nanomaterials to improve their chemical activities.In this work,we mainly improve the properties of materials by functionalizing C₂₄N₂₄ and borophene by doping with metal atoms.The main results are as follows:（1）The interactions between pristine C₂₄N₂₄ and metal doped C₂₄N₂₄ and six gas molecules（CO,CO₂,N₂,NH₃,NO,and NO₂）were analyzed by density functional theory（DFT）calculations.The pristine and metal-doped C₂₄N₂₄ have a specific response to certain gas according to adsorption energy,charge transfer,band gap and the density of states analyses.The calculated results show that after NO₂ adsorption,the band gap changes of K-and Na-doped C₂₄N₂₄ which corelate with its conductivity reach-12.75%and-26.67%,respectively,which is the most obvious among all the systems.K-C₂₄N₂₄ and Na-C₂₄N₂₄ were found to be more selective for NO₂ by analysis of the density of states and charge transfer.The recycle time of Na-C₂₄N₂₄ under ambient condition is also in the suitable range（1.80 s）.This study concludes the potential application of the Na-doped C₂₄N₂₄ as high-performance NO₂ sensor.（2）The interactions between borophene and Li doped borophene for SO₂ and five major atmospheric gases（CH₄,CO₂,N₂,CO,and H₂）were analyzed by DFT calculations.The analyses of the adsorption energy,charge transfer,density of states（DOS）and work function confirm the Li borophene is found to exhibit high selectivity and sensitivity to SO₂ molecules.By calculating the desorption time,Li-borophene may be a satisfactory SO₂ gas elimination material at room temperature since SO₂ could be adsorbed stably on the surface.when the working temperature rises to 498 K,the desorption time of SO₂ on Li borophene reaches 57.41 s,which means the SO₂ can be rapidly desorbed on the substrate for recycling.Therefore,Li-borophene can be a promising SO₂ gas sensor or scavenger at specific temperatures.（3）The interactions between boron nitride fullerenes nanostructures for anti-cancer drug hydroxyurea（HU）were analyzed by DFT calculations.The calculated results show that the variation of the adsorption energy with respect to the pyramidalization angle（PA）shows the adsorption energy is highly related with the PA.The electronic properties of boron nitride fullerenes nanostructures and drug molecules have been analyzed in terms of density of States,HOMO-LUMO orbitals and quantum molecular descriptors.The UV-Vis spectra of the drug-fullerene interaction system were also surveyed to explore the excited state properties of the drug-fullerene complexes.Drug release mechanism shows the drug can be released in the cancerous tissues where the p H is low.The results reveal the boron nitride fullerenes nanostructures can be a smart drug delivery carrier for HU drugs.