Theoretical Design Of Inorganic Perovskite And 2D Material For Optoelectronic Applications

With the energy crisis and environmental problems of human society,it's the key to find efficient,clean and sustainable energy materials for changing the current urgent situation.Hydrogen is viewed as the most potential new energy to replace traditional energy materials.It is the most ideal way to achieve this ultimate dream by utilizing solar energy or electric energy transformed from solar energy to complete water splitting and produce hydrogen.In order to achie,ve this goal,it becomes a hot topic and a challenge to search for appropriate optical/electrical catalysts.Inorganic perovskite materials as an improtant oxide semiconductor material have many advantages including high stability,low cost,safety and innocuity,and high abundance.Therefore,this kind of material is widely used in the field of photoelectricity.However,inorganic perovskite as a wide band gap semiconductor can only respond to ultraviolet light and not absorb visible light that takes up most of the sunlight,making the utilization ratio of solar energy low.Therefore,narrowing the band gap and expanding optical absorption band to the direction of visible light are the precondition of promoting the application of the photoelectric field.On the other hand,the transition metal chalcogendes are the currently research focus of electrocatalytic hydrogen evolution reaction and are considered to be promising materials for the current noble metal catalysts.Based on the two materials of BaTiO₃ and MoSe2 of the two kinds of materials mentioned above,it's studied of the doping modification of two kinds of materials by first principles calculation software VASP.The main contents of the research are as follows:?1?Through the research of 17 kinds of metals doped BaTiO₃,we investigated the crystal structure,binding energy,electronic structure,and carrier effective mass of different metal doped cubic BaTiO₃.Through a series of contrasts and screening,the doping of most transition metals is beneficial to the narrowing of the band gap of BaTiO₃.Based on the stability,electronic structure,effective quality and other factors,found that Fe,Mo replace Ti doped more effectively to improve the BaTiO₃ photoelectric properties.At the same time,we also proved by experiments of Mo doped BaTiO₃ that the absorption band edge had a significant red shift and the photocatalytic performance was improved.?2?Through the study of crystal structure,impurity formation energy,electronic structure and charge distribution of transition metal V-M" and Nb-M"?M":Mn,Fe,Cr,Co,Ni,Mo,Tc,Ru and Pd?co-doped BaTiO₃.It's can be found that V-M" Co-doped BaTiO₃ could better regulate the band gap by synergy between co-doping elements and the best doping system is V-Cr co-doping.?3?According to the experimental results,we obtained N doped 2H-MoSe2 can improve the Electrocatalytic Property.we theoretically investigated the effect of different N doping sites on the crystal structure,electronic structure,phase transition,and further designed process of the hydrogen evolution reaction process about 1T-MoSe2,2H-MoSe2 and N doped 2H-MoSe2.It indicated that N doped 2H-MoSe2 not only benefit to the phase transformation of 2H for the 1T phase,but also improve the electrocatalytic hydrogen evolution properties of materials.On the one hand,the calculated results illustrated the function rule of different metal doping/co-doping electronic structure,revealed the intrinsic mechanism of the enhancement of photocatalytic activity by modifying BaTiO₃ under different elements and different doping methods.And it provided a theoretical reference for the exploration of the actual experimental research of metal doping modification.On the other hand,we investigated the effect of N doped 2H-MoSe2 on the performance of electrocatalytic hydrogen evolution by design model.It explaned the reason why N doping can induce the transformation of 2H phase into 1T phase and reveal the intrinsic mechanism of N doping to improve the activity of 2H-MoSe2 electrocalytic hydrogen evolution.It provides a powerful theoretical basis for the experimental phenomenon.