Several Catalytic Reaction On Two Dimensional Materials:A Density Function Theory Study

With the increasing environmental and energy related concerns,research and development of new clean energy have stimulated intense interest.Proton exchange membrane fuel cells?PEMFC?and metal-air battery as sustainable and green energy conversion devices have received numerous attention.However,the slow rate of cathode electrochemical reaction has become a bottleneck for the performance of battery PEMFC and metal-air battery.Traditional commercial catalysts are known as the expensive and declining activity catalyst,which hinder the commercial application of devices.Therefore,it is an especially hot issue to investigate alternative electrocatalysts with low cost and excellent durability.Metal organic frameworks?MOFs?have become one of the most promising cathode catalysts due to their special structure and excellent performance.At the same time,converting CO₂ into chemical fuels is of particular meaningfulness for reducing the impact of greenhouse effect.However,The CO₂ molecule is extremely stable and the reaction requires suitable overpotentials,which is a big challenge for the electrochemical reduction of CO₂?CO₂ERR?.Thus,it is crucial to develop good electrocatalysts for CO₂ERR.Based on density functional theory,we investigate the oxygen reduction reaction?ORR?catalytic performance of M₃?HIB?₂,the M₃?THT?₂ as a bifunctional catalyst for ORR and oxygen evolution reaction?OER?,and the CO₂ERR catalytic performance of Tetra-M/MoN₂.The dissertation consist of as follows:Firstly,density functional theory calculations have been performed to investigate the catalytic activity of M₃?HIB?₂ complex nanosheets for the oxygen reduction reaction?ORR?,where HIB is hexaiminobenzene and M denotes Fe,Os,Ir or Pt.The results showed that the ORR activity of M₃?HIB?₂ is closely related to the selection of the central metal atom.The value of the overpotential increases in the order:Ir₃?HIB?₂<Fe₃?HIB?₂<Pt₃?HIB?₂<Os₃?HIB?₂.Due to its optimum adsorption strength and the smallest value of overpotential,the Ir₃?HIB?₂ nanosheet exhibits the best ORR catalytic activity among the four M₃?HIB?₂nanosheets.Secondly,theelectronicandcatalyticpropertiesofM₃?THT?₂nanosheets[M₃?triphenylene-2,3,6,7,10,11-hexathiol?₂]with nine different central metal atoms?Fe,Co,Ni,Ru,Rh,Pd,Os,Ir and Pt?are investigated systematically based on density functional theory.It is found that the electronic and catalytic properties of M₃?THT?₂ nanosheets are mainly based on the central metal atoms.Of the nine different M₃?THT?₂ nanosheets considered,Co₃?THT?₂ displays the best ORR catalytic activity,while Fe₃?THT?₂ shows the best OER catalytic activity.Due to the separation by THT molecules,the electronic and catalytic properties of MS₄ groups in bimetallic M₃?THT?₂ nanosheets are consistent with their single-metal counterparts.Bimetallic Fe_xCo_3-x?THT?₂ nanosheets exhibit bifunctional catalytic activity for both the ORR and OER.The ORR occurs on the Co atom,while the active site for the OER is the Fe atom.With desirable architecture and excellent electrocatalytic activities,the Fe_xCo_3-x?THT?₂ nanosheets can be considered as promising bifunctional oxygen electrocatalysts.Finally,the catalytic activity of transition metal doped Tetra-MoN₂ monolayer?Tetra-M/MoN₂?nanosheets?M denotes Fe,Co,Ni,Rh,Pd,Pt,Cu or Zn?for the CO₂ERR has been investigated based on density functional theory.The results showed that the incorporation of transition metal atom can significantly affect the catalytic activity of Tetra-M/MoN₂ toward the CO₂ERR,and the Tetra-Pd/MoN₂ nanosheet exhibits the best CO₂ERR catalytic activity due to its most favorable adsorption strength of CO₂ERR intermediate.