Synthesis Of Up-conversion Luminescence Materials Er³⁺:Y₃Al₅O₁₂ Combined With Visible-light Photocatalysts And Its Application In Hydrogen Production From Water Splitting

Fujishima and Honda published a paper on the journal of Nature in1972, whichdiscovered photoelectrochemical water splitting on a titanium dioxide (TiO2)electrode under ultraviolet light irradiation, since then it opened the prelude ofphotocatalytic hydrogen production from water splitting. From the current research,TiO2has been widely investigated in the field of photocatalysis due to its physicaland chemical stability, avirulence and cheapness, but it is still far from being a perfectand ideal photocatalyst. That is, due to the wide band gap (Ebg≥3.2eV), TiO2can bestimulated by the ultraviolet-light (λ≤378nm) to carry out the photocatalytic reaction.It is regrettable that the ultraviolet light only accounts for small proportion (<5.0%)of solar light, while the visible-light (~48%) and near-infrared-light (~44%) in solarlight can not be utilized by TiO2, which results in the quantum yield of TiO2is toolow.In recent years, we have been engaged in the study of TiO2combined withup-conversion luminescence agents to perform the visible-light photocatalyticdegradation of organic pollutants and achieved some satisfactory results. These canbe attributed to the up-conversion luminescence materials have the properties whichcan emit the high energy ultraviolet-light by absorbing the low energy visible-light.Since for TiO2there is a certain similarity in principle between the photocatalyticdegradation and photocatalytic hydrogen production from water splitting, we thinkthis method could also be applied to visible-light photocatalytic hydrogen productionfrom water splitting.In this study, the up-conversion luminescence material, Er3+:Y3Al5O12, wassynthesized by sol-gel method and its corresponding visible-light photocatalysts,Er3+:Y3Al5O12/Pt-TiO2composites, Er3+:Y3Al5O12/Pt-TiO2core-shell nanocompositesand Er3+:Y3Al5O12/Pt-KNbO3composites were successfully prepared by particlemixing and coating methods. For comparison, these photocatalysts are allcharacterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), excitation spectrum and emissionspectrum. And then, the influence factors such as Er3+:Y3Al5O12and TiO2, KNbO3mole ratio, heat-treated temperature, heat-treated time and initial pH value on thevisible-light photocatalytic hydrogen production activity of Er3+:Y3Al5O12/Pt-TiO2composites, Er3+:Y3Al5O12/Pt-TiO2core-shell nanocomposites andEr3+:Y3Al5O12/Pt-KNbO3composites are studied.Through the research on the preparation methods and properties ofEr3+:Y3Al5O12/Pt-TiO2composites, Er3+:Y3Al5O12/Pt-TiO2core-shell nanocompositesand Er3+:Y3Al5O12/Pt-KNbO3composites, we find that the up-conversionluminescence materials combine with traditional photocatalysts to prepare newphotocatalysts can provide a reference for photocatalytic hydrogen production fromwater splitting, which can provide a new way for large-scale hydrogen production inthe future.