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

Abstract

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.