Graphene-based Carbon Monoxide Catalyst And Formaldehyde Gas Sensor:The First Principles Study

Carbon monoxide(CO)and formaldehyde(HCHO)as two common air pollutants,to industrial production and people's daily life will have adverse consequences.Therefore,the timely removal of these pollutants or the detection of their concentration is very important,then the design of a highly efficient,energy-saving equipment for the catalytic oxidation of CO or HCHO gas detection is very practical.Graphene-based CO catalyst and HCHO gas sensor were designed by using the first-principles method based on density functional theory to simulate the behavior of CO-catalyzed reaction process and adsorption of HCHO.The main research results are divided into the following two parts:Firstly,the mechanism of the reaction of CO molecules on catalytic oxidation of nickel and pyridine nitrogen-modified graphene(Ni-3N-G)was explored.The results show that the oxidation process of CO needs to undergo two stages.The first stage follows the LH mechanism,that is,the interaction between CO and O2 is combined to form the intermediate OOCO,and then the intermediate product is gradually cleaved to produce CO2 molecules and leave an oxygen atom(CO+ O2? OOCO? CO2 + O),the reaction barriers required for the formation and cracking of intermediates were 0.61 eV and 0.51 eV,respectively.The second stage is the residual oxygen atom to continue to participate in the oxidation of CO,again generate CO2 molecules(CO + O2? CO2),this stage to overcome the reaction barrier is only 0.26 eV,which is much lower than the first stage of the reaction barrier.Therefore,Ni-3N-G as a catalyst without noble metal doping,with high catalytic activity,can be provided a new way of designing CO oxidation catalyst for industrial.Secondly,the adsorption characteristics of intrinsic graphene(Gra)and transition metal manganese doped graphene(Mn/Gra)for the formaldehyde gas molecules were comparatively studied.The results show that the doping of manganese atom has successfully opened the band gap of graphene,which increases the values of adsorption energy and the transfer charge of HCHO molecules,in other words,it enhances the adsorption abilities of HCHO molecules.The reason for the enhanced adsorption of HCHO is the orbital hybridization between Mn-3d and O-2p,C-2p in HCHO molecules.