Introduction Titanium dioxide(TiO2)is used as a photoelectric conversion material due to its non-toxicity,good photothermal stability and low cost.However,TiO2 has a wide electron bandgap,and its photo-generated electrons and holes are easy to recombine.The photoelectric performance of TiO2 is often improved via increasing the specific surface area,speeding up the axial transport of electrons.In this paper,titanium dioxide inverse opal photonic crystals(TiO2 IOPCs)were selected as photoelectric conversion materials due to the advantages of large specific surface area and promoted light absorption.TiO2 IOPCs were prepared by a template method and a sol-gel method.Also,TiO2 IOPCs was modified with amorphous titanium dioxide(A-TiO2).Methods Self-assembled opal photonic crystals on fluorine-doped tin oxide(FTO)were used as templates.The precursor liquid prepared with isopropyl titanate,ethanol,acetyl acetone,hydrochloric acid and deionized water was filled into the gap of opal photonic crystal.After the sol in the opal crystal gap was dried and gelled,the electrode was calcined at 450℃to remove the opal photonic crystals template to obtain TiO2 IOPCs.Afterwards,amorphous titanium dioxide modified titanium dioxide inverse opal photonic crystals(A-TiO2/TiO2 IOPCs)were prepared via placing TiO2 IOPCs electrodes into TiCl4 aqueous solution at a low temperature without stirring.The phase composition,elemental composition,energy level structure and morphology of the electrode were analyzed by X-ray diffraction(XRD),X-ray electron spectroscopy(XPS),ultraviolet visible spectrophotometry(UV-VIS)and scanning electron microscopy(SEM).A three-electrode system was used to detect the photocurrent in the dark,and the LED with 390-410 nm was used as an excitation light source.The current-time(I-T)curve was recorded when the light source was switched.Results and Discussion The XRD patterns show that amorphous titanium dioxide modified anatase titanium dioxide electrode can be obtained.Based on the XPS analysis,the prepared material is TiO2.The valence band value of the electrode is determined by the XPS valence band spectra.The indirect band gap of the electrode material is determined according to the UV-VIS analysis.The conduction band value of the electrode can be obtained by calculation.The SEM images indicate that A layer of amorphous titanium dioxide is deposited on the orderly arranged porous skeleton of TiO2 IOPCs,which retains a porous structure and further increases the specific surface area.In the photocurrent test,TiO2 IOPCs photocurrent reaches 100 nA,and the photocurrent of A-TiO2/TiO2 IOPCs reaches 600 nA,indicating that its photocurrent is increased by 6 times.The conduction band value of A-TiO2 is more negative than that of anatase TiO2 IOPCs.The photogenerated electrons of A-TiO2 can be transferred to the conduction band of anatase TiO2 IOPCs.The valence band value of anatase TiO2 IOPCs is more positive than that of A-TiO2,and the photogenerated holes can be transferred from the anatase TiO2 IOPCs valence band to A-TiO2 valence band,thereby reducing the recombination of photogenerated electrons and holes.In addition,the light absorption area increases due to the porous structure of A-TiO2/TiO2 IOPCs,thus increasing the photocurrent.Conclusions TiO2 IOPCs were prepared by a template method and a sol-gel method,and then amorphous TiO2 was deposited on TiO2 IOPCs skeleton at a low temperature to prepare an amorphous titanium dioxide modified titanium dioxide inverse opal photonic crystal electrode.The porous structure of the electrode increased the light absorption area,and the modification of amorphous titanium dioxide reduced the recombination of photogenerated electrons and holes,and the photocurrent of the electrode was increased by 4 times.The results indicated that this method could be simple and feasible,which could obtain the superior photoelectric performance of the electrode,thus providing an effective approach for the development of green energy.
国家科技期刊平台
NSTL
万方数据
