The Precise Regulation On Electronic Structure Of Two-dimension Materials Towards Application In Electrocatalysis And Photo-electrocatalysis

Precise manipulation in electronic structure of the functional materials is essential towards optimization of the corresponding electrochemical and photo-electrochemical performance.On the one hand,density function theory(DFT)calculation on the single-atom catalyst could uncover the electronic structure,especially the insight into charge and orbital level,of the single atom.Then,it could clarify the structure-function relationship between the electronic structure of the singe atom and catalytic process,thus guiding the synthesis and optimization of catalyst.One the other hand,the advanced characterization technology could verify the calculation results,and resolve the active center at electronic-structure level.Thus,it could motivate the rational design of catalyst and shorten the cycle of the industrialization.This thesis contains the following parts:(1)Single-atom catalysts have attracted much attention.This work reported herein is that regulating charge transfer of lattice oxygen atoms in serial single-atom-doped titania enables tunable hydrogen evolution reaction(HER)activity.First principles calculations disclose that the activity of latticeoxygen for the HER can be regularly promoted by substitutingits nearest metal atom,and doping-induced charge transfer plays an essential role.Besides,the realm of the charge transfer of the active site can be enlarged to the second nearest atom by creating oxygen vacancies,resulting in further optimization for the HER.Various single-atom-doped titania nanosheets were fabricated to validate the proposed model.Taking advantage of the localized charge transfer to the lattice atom is demonstrated to be feasible for realizing precise regulation of the electronic structures and thus catalytic activity of the nanosheets.(2)Dual-site catalyst allows for a synergetic reaction in the close proximity to enhance catalysis.It is highly desirable to create dual-site interfaces in single-atom system in order to maximize the effect.Herein,we report on a cation-deficient electrostatic anchorage route to fabricate an atomically dispersed platinum-titania catalyst(Pt1O1/Ti1-xO2),which shows greatly enhanced hydrogen evolution activity,surpassing that of the commercial Pt/C catalyst in mass by a factor of 53.2.Operando techniques and density functional theory calculations reveal that Pt1O1/Ti1-xO2 experiences a Pt-O dual-site catalytic pathway,where the inherent charge transfer within the dual sites encourages the jointly coupling protons and plays the key role during the Volmer-Tafel process.There is almost no decay in the activity of Pt1O1/Ti1-xO2 over 300,000 cycles,meaning 30 times of enhancement in stability compared to the commercial Pt/C catalysts(10,000 cycles).(3)It is important to improve the oxygen reduction reaction(ORR)performance of Pt by alloying it with first-row transition metals(M:e.g.,Fe,Co,Ni).It is known that the ligand,strain,and ensemble effects govern the ORR performance.However,the intrinsic magnetic characteristics of PtMs have rarely been focused on in ORR investigations.Here,we employed a hard-magnet L10-ordered PtFe nanopillar film(Llo-PtFe NF)as model catalyst to uncover the catalyst's magnetic effect on the ORR.We report a five-fold enhancement of the catalytic efficiency of magnetized L10-PtFe(M)NF compared with unmagnetized one.Further investigations demonstrate that the coverage of chemisorbed oxygen on catalyst surface,especially the primary Pt dyz-O2?*coupling,manipulated by the catalyst's magnetic field is the key factor for the ORR regulation.This work thus paves the way for the implementation of magnetic effect towards the precise regulation in broad catalysis applications.