Theoretical Investigation On The Catalytic Performance In Electrochemical Synthesis Ammonia Of Mo-based Chalcogenides

As one of the most widely used inorganic compounds in the world,ammonia plays a vital role in human survival and social production.As the most commonly used process in ammonia synthesis,the Haber-Bosch not solely consumes excessive non-renewable energy but also cause massive CO₂ emission.Consequently,economical and environmental alternatives for Haber-Bosch are imperative,such as the recently proposed NRR and NOER which are both efficient and flexible,and accordingly demand relevant efficient catalysts.Recent studies have developed Mo-based chalcogenides materials provided with distinctive structure and physicochemical properties,as well as achieving research advances in the electrochemical synthesis of ammonia owing to Molybdenum is a non-toxic,low-cost transition metal.This paper focus on exploring the application prospect of low dimensional Mo-based chalcogenides materials applied in the electrochemical synthesis of ammonia,filtering ideal catalysts assessed by stability,selectivity and efficiency.The details are as follows:（1）According to the First-principles the calculating analysis evaluates the feasibility of X_v-Mo₆X₆（X=S,Se,Te）nanowires with anion vacancy serving as NRR catalysts.The results suggest that anion vacancy may perform active centers in catalytic reaction,besides the unsaturated Molybdenum atoms originated from anion vacancy could fix and activate inertia N₂ molecules.By free energy calculation,S_v-Mo₆S₆,Se_v-Mo₆Se₆ and Te_v-Mo₆Te₆ are all three appropriate NRR catalysts to choose from,among which S_v-Mo₆S₆ being the best,for attaching N₂ in side-on mode with ambient temperature,-0.26V applied voltage,and reducing N₂ to NH₃ via consecutive pathway.Advantages make S_v-Mo₆S₆ reactive as catalyst in NRR include strong charge transfer caused by anion vacancy,d-band center near Fermi level,and excellent selectivity.Based on the obtained results,the study is supposed to cast light on the studies of a new process in ammonia synthesis.（2）At the point of First-principles,the systemic investigations on the NOER performance of TM/Mo S₂ materials,fabricated by doping single transition element atom to S_v-Mo S₂substrates,apply eight potential thermodynamically stable materials by comparing its binding and cohesive energy to further evaluate the catalytic performance.Subsequently,Au/Mo S₂ modified by single Au atom is identified as the ideal catalyst in NOER for attaching NO molecular at a moderate ratio,as well as the relatively low energy barrier during first hydrogenation.By inference of Gibbs free energy diagram,the Au/Mo S₂ may reduce N₂ molecules with excellent catalytic activity under ambient condition,and decisive step energy barrier as low as 0.16e V both in N-distal and N-alternating pathway.Moreover,an alternative immanent reason by the angle of electronic characteristic and spin polarization may explicate the high catalytic activity of Au/Mo S₂ in NOER as well.Findings of the research come up with an ideal probable catalyst for NOER,by means of establishing procedure used for searching potential single atom catalysts on the basis of inherent mechanism.