Highly efficient near-infrared light photocatalytic hydrogen evolution over MoS2 supported Ta2O5 combined with an up-conversion luminescence agent (β-Tm3+,Yb3+:NaYF4/MoS2–Ta2O5 nanocomposite)

Abstract

Here, an effective infrared-ultraviolet up-conversion luminescence agent (β-Tm³⁺,Yb³⁺:NaYF₄) is synthesized by a hydrothermal method and the corresponding photocatalyst (β-Tm³⁺,Yb³⁺:NaYF₄/MoS₂–Ta₂O₅) is successfully prepared. The compositions and morphologies of the prepared β-Tm³⁺,Yb³⁺:NaYF₄, MoS₂–Ta₂O₅ and β-Tm³⁺,Yb³⁺:NaYF₄/MoS₂–Ta₂O₅ are all characterized by XRD, SEM, EDX, and FT-IR techniques. The photocatalytic activity of β-Tm³⁺,Yb³⁺:NaYF₄/MoS₂–Ta₂O₅ is examined through the photocatalytic hydrogen evolution from an aqueous methanol solution under near-infrared light irradiation. In addition, the influence of factors such as the mass ratio of β-Tm³⁺,Yb³⁺:NaYF₄ and MoS₂–Ta₂O₅, the heat-treatment temperature, and the initial pH value of the solution on the photocatalytic hydrogen evolution activity of β-Tm³⁺,Yb³⁺:NaYF₄/MoS₂–Ta₂O₅ is also studied. The results show that the photocatalytic hydrogen evolution activity of Ta₂O₅ can be greatly enhanced by adding the up-conversion luminescence agent (β-Tm³⁺,Yb³⁺:NaYF₄) and co-catalyst (MoS₂). Furthermore, the β-Tm³⁺,Yb³⁺:NaYF₄/MoS₂–Ta₂O₅ catalyst with a 40 : 100 mass ratio which was heat-treated at 450 °C for 60 min in an aqueous methanol solution at initial pH = 6.0 displays the highest photocatalytic activity under near-infrared light irradiation.