Construction And Performance Evaluation Of Nanoporous Platinum On TiO₂

In order to effectively increase the photocatalytic activity of the material,the noble metal Pt is usually supported as a co-catalyst on the surface of the bulk catalyst.However,Pt is rare and expensive in the earth's crust,so it is important to reduce the amount of platinum while maintaining high photocatalytic activity.In this work,this paper proposes a method of selectively dissolving alloys to construct a porous Pt co-catalyst and used it in photocatalysis research.The specific work is as follows:?1?Pt-Ni alloy particles are supported on P25 by ultrasonic-chemical reduction,In this process,the surfactant polyvinylpyrrolidone?PVP?and polyethylene glycol octylphenyl ether?Triton X-100?were added,and the two surfactants synergistically obtained highly dispersed and fine alloy particles.The Ni atom in the alloy is selectively removed by chemical demetallization method to obtain a Pt co-catalyst of nano-sized hollow pores.The content of Pt in the sample is 3 wt.%and the surface pore size is about 1 nm.Excitingly,the particle size of the porous structure after the addition of the surfactant is smaller from the original 5 nm to3 nm.Compared with the non-porous pure Pt promoter,the obtained sample has a photocatalytic activity of degrading the methylene blue?MB?dye by a factor of three,and the average hydrogen production performance of water decomposition is 2.4 times.At the same time,the possible mechanism of the samples formation and the photo-carrier transport mechanism were analyzed.The experimental results show that OH·and·O₂^-are the active species that play a major role in photocatalysis.?2?The porous structure Pt particles are supported on TiO₂ nanotubes as co-catalyst.Pt-Ni alloy particles are highly dispersed in the tube wall and nozzle by adding a surfactant during chemical reduction.The size of these undemetallized alloy particles is from 130-160nm to 8-12 nm.The Ni atoms in alloys was selectively removed by chemical demetallization method,and a porous Pt co-catalyst with a pore diameter of 2-3 nm was obtained.This part of the work focuses on the effect of surfactant ratio and demetallization time on sample activity.And the sample with the surfactant porous Pt co-catalyst has a photocatalytic activity up to 4times compared to the non-porous pure Pt co-catalyst.In addition,the photocurrent stability of the sample was examined,and the photocarrier transport mechanism in the related reaction process was analyzed.?3?In this work,p-n heterostructured composite catalysts were prepared by electrochemical reduction-heat treatment with the assistance of surfactants.The addition of a surfactant during the electrochemical reduction resulted in a finer and more uniform Co₃O₄loading on the TiO₂ nanotubes.SEM clearly shows that the particle size and spatial distribution of the load are more uniform by the synergistic action of the two surfactants.The morphology of Co₃O₄ particles loaded on the TiO₂ nanotubes,not only improves the photocurrent properties of samples and the performance of degradation of methylene blue ?MB?dyes under ultraviolet light,but also extends to the use of visible light.