Synthesis And Photocatalytic Properties Of Cu₂O Nanoparticles

Cuprous oxide(Cu2O),as a p-type semiconductor with a direct band gap of 2.17 eV,has attracted considerable attention due to its excellent performance in visible-light photocatalysis.Since the catalytic activity of Cu2O is significantly influenced by its morphology,size and size distribution,developing an effective strategy for the controllable synthesis of Cu2O crystals has been an imperative task and extensive investigations have been performed.Among various approaches,precipitation method has been extensively applied in many reactions by the virtue of flexibility and controllability.During the precipitation process,the reaction temperature and supersaturation have a significant effect on the size and uniformity of products.Traditional batch reactors often suffer from the back-mixing,scale-up and repeatability from batch to batch,which lead to the nonuniformity of products.Recently,continuous flow microreactors open a new view to scientists since they can operate continuously under a constant flow rate and without amplification effect.In addition,they provide high volume-to-area ratio which promises high efficiency of mass transfer and heat transfer,thus enable to precisely control the reaction temperature and residence time.In this work,Cu2O nanoparticles were synthesized by precipitation method via T-Shaped micromixers and a batch reactor,the effects of process parameters on the morphology,size and size distribution of Cu2O nanoparticles were investigated,and the photocatalytic activity was evaluated.The main contents are as follows:1.Cu2O nanoparticles were successfully synthesized by precipitation method via T-Shaped micromixers.The influences of reaction temperature,Cu2+ sources,sodium hydroxide concentration,ascorbic acid concentration,feed flow rate,the molecular weight and dosage of polyethylene glycol and the dosage of polyvinyl pyrrolidone on the morphology,size and size distribution of Cu2O nanoparticles were investigated.The results indicated that the size and size distribution can be delicate controlled by varying these process parameters.Besides,the selective adsorption of template on the crystal face leading to the morphologies variation in the final crystals.2.The effects of T-Shaped micromixer and batch reactor on the size and size distribution of Cu2O were studied under the same process conditions.The results showed that the size of Cu2O particles synthesized via T-Shaped micromixer is smaller and the size distribution is narrower.3.The photocatalytic activity of as-prepared Cu2O nanoparticles on the degradation of methyl orange,methyl violet,methylene blue and acid magenta were carried out.The effects of the particle size,dosage and repeat times of Cu2O nanoparticles on the photocatalytic degradation of methyl orange were investigated,and the kinetic model of degradation of methyl orange was further discussed.The results indicated that Cu2O showed better photocatalytic performance to methyl orange and acid magenta than methyl violet and methylene blue.There was an optimal degradation efficiency of methyl orange on Cu2O dosage,while the degradation efficiency of Cu2O was increased with the decrease of size in Cu2O.Cu2O still exhibited the desired degradation efficiency after repeated used four times.Besides,the kinetic curves of degradation of methyl orange solution consistent with the first-order kinetics model.