Synthesis Of Er³⁺:Y₃Al₅O₁₂-ZnS-dual Cocatalysts Compound Catalytic System And Its Application In Visible-light Photocatalytic Hydrogen Production From Water Splitting

Semiconductor photocatalytic technology has wide application prospects for water splitting. In many kinds of semiconductor materials, ZnS have been intensively studied as active photocatalysts due to cheap, stable, non-toxic and corrosion resistance, etc. Owing to relatively wide band gap (Eg= 3.6 eV), it can be activated mainly under ultraviolet-light which accounts for less than 5.0% of the solar light and therefore imposes restrictions on the application of solar light. Thence, expanding the utilization of solar light for ZnS is one of the focus areas of hydrogen production from water splitting.Recently, in our researches a new improved method was proposed, that is, Wide band gap semiconductor is combined with up-conversion luminescence agent to improve photocatalytic hydrogen production from water splitting. up-conversion luminescence agent, which can convert longer wavelength radiation to shorter wavelength fluorescence via a two-photon or multi-photon mechanism for satisfing the requirements of wide band-gap semiconductor materials ZnS, which achieve a higher efficiency of photocatalytic hydrogen production from water splitting.So far, the efficiency of photocatalytic hydrogen production from water splitting is still low. A key reason is that the photogenerated electrons/holes are easily consumed via recombination. In order to promote the rapid surface transfer of photogenerated electrons and holes from photocatalyst, the widely used strategy for achieving this purpose is loading cocatalysts.In this paper, a series of experiment were investigated about the photocatalytic hydrogen production performance of ZnS. Through the combination of wide band gap semiconductor and up-conversion luminescence agent, many novel catalytic materials, Er3+:Y3Al5O12/Pt-PdS/ZnS2, Er3+:Y3Al5O12/PdS-ZnS-MoX2 (X= O, S and Se) and Er3+:Y3Al5O12/RuO2-ZnS-(MoSe2-RGO), was successfully prepared. The prepared samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX). UV-vis absorption and PL spectra of Er3+:Y3Al5O12 were also determined. In addition, some influential factors on the photocatalytic hydrogen production were investigated in detail, such as Er3+：Y3Al5O12 and ZnS mass ratio, cocatalyst amount and reusability of the photocatalyst, etc.Through the research of compound materials mentioned above. we found that compositing the up-conversion luminescent material with traditional photocatalyst and loading the cocatalyst onto the photocatalyst can provide a reference for visible-light photocatalytic water splitting for hydrogen production. Perhaps, it provides a possible strategy for large-sale hydrogen production using solar energy in the future.