Preparation And Property Study Of Bio-inspired Spiky TiO₂/Au Nanorods Photocatalyst

Energy shortage and rising environmental problems have been increasingly serious and it has become extremely urgent to seek alternative clean energy resources.Photocatalytic technology using clean and renewable sunlight can drive a series of important chemical reactions,such as degradation of pollutants,photolysis of water to produce hydrogen.Photoelectric conversion technology can directly convert solar energy into electric energy through photovoltaic effect.Therefore,it is of great significance to develop photocatalytic materials and optoelectronic materials to solve environmental pollution and energy problems.Ti O₂ decorated with noble metal has been a hot topic,because that the surface plasmon resonance（SPR）effect of noble metals in the visible region can expand the light absorption and promote the separation of photoelectron-hole pairs,thus improving the photoquantum efficiency.In addition,inspired by sea urchin and pollen grains in nature,spiky nanostructures receive more attention due to their unique properties of high specific surface area and reduced reflectance.Consequently,based on the structure bio-inspired idea,combining the spiky structure with the TiO₂/noble metal nanorod nanocomposite materials is beneficial to improve the photocatalytic activity and photoconversion performance.Herein,we show the preparation of spiky TiO₂/Au nanorod（TiO₂/AuNR）nanocomposite materials,and investigated the photocatalytic properties and photoconversion properties.The detailed contents are as follows:（1）We have prepared different aspect ratios of AuNR（2.5,2.7,4.1 and 4.5）by seeds-mediated procedures.Four bio-inspired spiky TiO₂/AuNR nanohybrids are prepared through the in situ nucleation and growth of spiky TiO₂ in the AuNR solution,which are TiO₂/AuNR-685,TiO₂/AuNR-730,TiO₂/AuNR-805 and TiO₂/AuNR-850,respectively.The UV-vis absorption and diffuse reflectance spectra indicate that the bio-inspired nanohybrid materials show significantly enhanced light harvesting efficiency due to the AuNR with two SPR absorption bands in the visible region that broaden the absorption range and the spiky structure decreasing the reflectivity of light.The visible light photocatalytic degradation capability of these bio-inspired nanohybrid materials are studied in detail,and compared with the bare AuNR,commercial TiO₂ and bio-inspired spiky TiO₂/Au nanosphere photocatalysts.The degradation curves are drawn and the degradation rate is calculated by fitted curves.These four bio-inspired TiO₂/AuNR photocatalysts all exhibit enhanced photocatalytic activity compared to the contrast,and the degradation efficiency of Rhodamine B is over 90%in 90 min under visible light,which can be attributed to the increased light harvesting,photocharge utilization and specific surface area.Specially,the bio-inspired spiky TiO₂/AuNR-685 nanohybrid shows the best photocatalytic activity,degrading 98.9%of Rhodamine B in 90 min.In addition,the recycle ability is also studied.The bio-inspired spiky nanohybrids with significantly enhanced visible light response performance decreased light reflectivity and improved light harvesting can be applied in the environment and energy field.（2）We study the photocatalytic hydrogen production and photoelectric conversion performance by bio-inspired spiky TiO₂/AuNR-685 nanohybrids.Bio-inspired spiky TiO₂,commercial TiO₂ and bare AuNR as the contrast and methanol as the sacrificial agent,we investigate the photocatalytic hydrogen production rate under visible light and simulated solar light irradiation.Under simulated solar light irradiation,the bio-inspired spiky TiO₂/AuNR-685 nanohybrid exhibits the best hydrogen production rate which is 1.81 mmol g^-1 h^-1.The recycle ability is also studied.Under visible light irradiation,the hydrogen production rate of bio-inspired spiky TiO₂/AuNR-685nanohybrid is 0.06 mmol g^-1 h^-1,while there is no hydrogen produced by the bio-inspired spiky TiO₂ and commercial TiO₂.We investigate the photoelectric conversion performance of bio-inspired spiky TiO₂/AuNR nanohybrid by coating on ITO glass as photoanode.A three-electrode system is set up to study the photocurrent properties under visible light and simulated solar light.Compared to bio-inspired spiky TiO₂ and commercial TiO₂,a fast and stable photocurrent is observed for the bio-inspired spiky TiO₂/AuNR nanohybrid photoelectrode and the impedance is the smallest,which indicates a rapid charge transfer and good photoelectric conversion performance.This bio-inspired nanohybrid provides a new idea for the preparation of new photocatalysts and optoelectronic materials.