Construction Of High Efficient Semiconductor Photocatalyst Based On Crystal-facet Engineering And Selective Modification

Solving the current environmental pollution and energy crisis is the primary task of achieving human sustainable development.Photocatalysis technology is considered to be one of the most promising technologies to accomplish this task.However,at present,there are many problems such as bulk recombination of photogenerated charge carriers,slow interfacial reaction,and low visible-light absorption,which greatly limits its practical application.Recent studies have shown that combining crystal-facet engineering and selective modification is an effective strategy to reduce the carrier recombination,accelerate interfacial catalytic reaction,and broaden visible-light absorption range,thus improving the photocatalytic performance of photocatalysts.To achieve performance improvement of traditional photocatalysts such as TiO2 and BiVO4,we have carried out the following exploration based oncrystal-facet engineering and selective modification:preparation and performance study of?1?Ag/F-TiO₂ nanosheet photocatalyst and?2?Z-scheme Pt-Au/BiVO₄nanosheet photocatalyst.The main results are as follows:1,TiO₂ photocatalyst is one of the most widely studied photocatalysts because of its chemical stability,low cost,and abundant resources.However,due to the fact that the bulk recombination of photogenerated charge carriers and slow interfacial reactionis not solved well still,its further development is greatly restricted.In this work,using TiOSO₄ as the Ti precursor and HF acid as the capping agent synthesizes F-TiO₂ nanosheet photocatalyst with hole cocatalyst F^-selectively adsorbed on the?001?facet of TiO2 through a facile hydrothermal method,and then using AgNO3 as the Ag precursor synthesizes Ag/F-TiO₂ nanosheet photocatalyst with electron cocatalyst Ag nanoparticles selectively deposited on the?101?facet of TiO₂ through a photodeposition procedure.The experimental results showed that Ag/F-TiO2(k=8.48×10^-44 min^-1)nanosheet photocatalyst exhibited higher photocatalytic performance than TiO₂(1.65×10^-44 min^-1),F-TiO₂(7.26×10^-44 min^-1),Ag/TiO₂(3.58×10^-44 min^-1),and Ag/F-TiO₂?R?(3.43×10^-44 min^-1)nanosheet photocatalyst by a factor of 5.14,1.17,2.37,and 2.47 times,respectively.Based on the analysis of performance and characterization,the photocatalytic mechanism is explainedthat the orientation transfer of photogenerated charges and rapid interfacial catalytic reaction synergistically promotes the enhanced photocatalytic performance of Ag/F-TiO₂photocatalyst.2,BiVO₄ is widely used in the field of visible-light photocatalysis because of its special optical and physical properties,but its practical applicationis also limited due to bulk recombination of photogenerated charge carriers,slow interfacial reaction,and low visible-light absorption.In this work,with the control of stirring speed,reaction temperature,and reaction time,BiVO₄ nanosheet photocatalyst is synthesized through a facile hydrothermal method using NH₄VO₃ as the V precursor,Bi?NO₃?₃ as the Bi precursor,and concentrated ammonia as the capping agent.Subsequently,Z-scheme Pt-Au/BiVO₄ nanosheet photocatalyst was controllably synthesized by photodeposition of Au nanoparticles on the?010?facet of BiVO₄ and following photodeposition of Pt nanoparticles on the surface of Au.The experimental results showed that Pt-Au/BiVO₄(2.45×10^-22 min^-1)nanosheet photocatalyst compared with exhibited higher photocatalytic performance than BiVO₄(?0 min^-1),Pt/BiVO₄(1.17×10^-22 min^-1),Au/BiVO₄(3.29×10^-33 min^-1),and Au,Pt/BiVO₄?R?(6.81×10^-33 min^-1)nanosheet photocatalyst.Based on the performance and characterization,the photocatalytic mechanism is explained that the orientation transfer of photogenerated charges,rapid interfacial carrier transfer and interfacial catalytic reaction of electrons,as well as local plasma resonance effect of Au nanoparticles synergistically promote the enhanced visible-light photocatalytic performance of Pt-Au/BiVO₄ photocatalyst.