The Effects On Sensitizing Two Dimensional Inorganic Semiconductors And Photocatlytic Water Oxidation By Perylene-3,4,9,10-tetracarboxylic Acid

The global energy crisis and environmental pollution are increasingly severe,which has seriously affected the survival and sustainable development of mankind.Using semiconductor photocatalysts to convert solar energy into hydrogen and oxygen is considered as one of the most ideal solutions.However,the oxygen evolution reaction,a half reaction of photocatalytic water splitting,is a complex four-electron reaction,which limits the rate of water splitting.How to use the broadband light to induce charge separation and directional transport during the oxygen evolution semi-reaction process,and suppress the photo-generated charges recombination is the key issue to improve the photocatalytic oxygen evolution efficiency.Using organic functional molecules to sensitize inorganic semiconductor materials,through the synergy between organic and inorganic components,is expected to improve the light absorption efficiency and electron transport capability of materials.In this paper,2D PTCAD/In2O3 nanosheets and 2D PTCAD/Mn2O3 nanosheets were prepared by using perylene-3,4,9,10-tetracarboxylic acid(PTCAD)as dye sensitizing molecules.We put emphasis on the influence of organic functional molecules on visible light utilization rate,band structure,charge separation and transportation,and water oxidation performance.This research provides guidance for designing and optimizing novel organic-inorganic hybrid photocatalytic materials.1.Perylene-3,4,9,10-tetracarboxylic acid accelerated light-driven water oxidation on ultrathin indium oxide porous sheetswe report the utilization of the ?-conjugated perylene-3,4,9,10-tetracarboxylic acid(PTCAD)molecule as electron donor to promote photocatalytic activity by narrowing the band gap,facilitating charge generation and separation,and reducing overpotential,manipulating the lattice plane,and promoting PCET process toward water oxidation.As detailed in this thesis,PTCAD bonded 2D porous In2O3 nanosheets,PTCAD/In2O3 NSs,was developed by in-situ synthesis using PTCAD as mixed ligand.The performance of the PTCAD was investigated in structural and electronic effects,respectively.Structurally,PTCAD with low content has little effect on the morphology,specific surface area,lattice plane,oxidation state,and O-vacancy of the In2O3 NS.Thus,it provides a simplified platform to focus on the function of the organic PTCAD.However,it is notable that PTCAD indeed has interposed the crystal orientation growth,where small amount of PTCAD leads to much more exposed catalytic active lattice plane,while overloaded PTCAD results in passivated lattice plane.This may provide a hint for constructing active nanocrystallines by manipulating the lattice plane with organic molecules.Moreover,the PTCAD content has strongly relationship with electronic effects including BG,overpotential and charge separation efficiency.It is demonstrated that the presence of PTCAD indeed exerted great positive effects on promoting the photocatalytic activity.Specifically,loading amount of PTCAD with 0.5 to I mole fraction is optimal in reducing BG and suppressing the electron-holes recombination.All the performance improvement should be the consequence of the synergy effect between the PTCAD and In2O3 NS,including the strong bonding and electron-coupling,large thermodynamic driving force,PCET processes,associated with the 2D-confined high carrier mobility provided by the In2O3 NS.We believe that this work provides new insights to understand the coordination between organic and inorganic components and possibilities for development of organic/inorganic hybrid photocatalysts with functional dye molecules that can synergistically improve the broadband-light utilization and photo-induced charge separation2.Effects of perylene-3,4,9,10-tetracarboxylic acid on two-dimensional structure and photoelectric properties of Mn2O3The PTCAD/Mn2O3 nanosheets with two-dimensional structure were successfully prepared by hydrothermal method using PTCAD as organic functional molecule.Due to the regulation of PTCAD,the composite materials are transformed from the original irregular bulk shape of Mn2O3 into a regular two-dimensional nanosheet structure,which is conducive to the rapid transport of photogenerated carriers to the surface,reduceing electron-hole recombination,increasing the specific surface area,and exposuring more reactive sites,etc.Electrochemical characterization of a series of PTCAD/Mn2O3 nanosheets showed that appropriate amount of PTCAD organic molecules played a significant role in reducing the overpotential of the composite,decreasing the electrochemical impedance,and promoting the photocurrent intensity.This work shows positive guidance for the synthesis of novel two-dimensional photocatalytic materials and the improvement of photocatalytic efficiency of organic-inorganic composites.