The effect of different co-catalysts (CuO, MoS₂ and Pt) on hydrogen production of Er³⁺:YAlO₃/NaTaO₃ by visible-light-induced methanol splitting

In this work, a high effective up-conversion luminescence agent (from infrared and visible light to ultraviolet light), Er³⁺:YAlO₃, was synthesized by sol–gel method. And then, the CuO, MoS₂ and Pt were adopted as co-catalysts and the NaTaO₃ was used as bulk catalyst, and then the three corresponding visible-light photocatalysts, Er³⁺:YAlO₃/CuO–NaTaO₃, Er³⁺:YAlO₃/MoS₂–NaTaO₃ and Er³⁺:YAlO₃/Pt–NaTaO₃, were successfully prepared by hydrothermal and direct mixing methods, respectively. Er³⁺:YAlO₃, NaTaO₃, Er³⁺:YAlO₃/CuO–NaTaO₃, Er³⁺:YAlO₃/MoS₂–NaTaO₃ and Er³⁺:YAlO₃/Pt–NaTaO₃ were all characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The visible-light photocatalytic activities of Er³⁺:YAlO₃/CuO–NaTaO₃, Er³⁺:YAlO₃/MoS₂–NaTaO₃ and Er³⁺:YAlO₃/Pt–NaTaO₃ were examined through photocatalytic hydrogen evolution from methanol aqueous solution under visible-light irradiation. The influence factors such as the contents of co-catalysts (CuO, MoS₂ and Pt), heat-treated temperature and initial pH value on the visible-light photocatalytic hydrogen evolution activity of Er³⁺:YAlO₃/CuO–NaTaO₃, Er³⁺:YAlO₃/MoS₂–NaTaO₃ and Er³⁺:YAlO₃/Pt–NaTaO₃ were studied. The results showed that the Er³⁺:YAlO₃/MoS₂–NaTaO₃ with 0.2 wt% MoS₂ in solution (pH = 6.0) with 5.0 wt% methanol displayed the highest visible light photocatalytic hydrogen production activity. - Highlights: • CuO, MoS₂, Pt loaded Er:YAP/NaTaO₃ visible-light photocatalysts were prepared. • CuO, MoS₂, Pt can promote Er:YAP/NaTaO₃ visible-light photocatalytic H₂ production. • Er:YAP/MoS₂–NaTaO₃ shows a high visible-light photocatalytic H₂ production activity.