An effective quaternary nano-sized Er3+:Y3Al5O12/Pt–PdS/ZnS visible-light photocatalyst for H2 production

A highly effective and stable up-conversion luminescence agent, Er3+:Y3Al5O12, was synthesized by sol–gel and calcination methods. Then, as a novel visible-light photocatalyst, Er3+:Y3Al5O12, Pt and PdS (as dual co-catalysts) decorated ZnS nano-sized composites, Er3+:Y3Al5O12/Pt–PdS/ZnS, were fabricated by deposition–precipitation and ultrasonic dispersion methods. All 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. The visible-light photocatalytic H2 production activity of the prepared Er3+:Y3Al5O12/Pt–PdS/ZnS was evaluated by using Na2S and Na2SO3 as sacrificial reagents in an aqueous solution under 300 W irradiation from a xenon lamp. In addition, some influential factors such as Er3+:Y3Al5O12 and ZnS mass ratio, catalyst amount, irradiation time and irradiation intensity on visible-light photocatalytic H2 production of Er3+:Y3Al5O12/Pt–PdS/ZnS were investigated in detail. It was found that Er3+:Y3Al5O12 can effectively improve the visible-light photocatalytic activity of ZnS. Particularly, Er3+:Y3Al5O12/Pt–PdS/ZnS with 0.13 wt% PdS and 0.3 wt% Pt and a 0.30 : 1.00 mass ratio shows the highest photocatalytic H2 production activity in the sulfide/sulfite (0.2 mol L−1 Na2S and 0.3 mol L−1 Na2SO3) aqueous solution as sacrificial reagents.