Nitrogen doped Sr₂Ta₂O₇ coupled with graphene sheets as photocatalysts for increased photocatalytic hydrogen production.

Abstract

In this work we present the synthesis of a new type of nitrogen-doped tantalate, Sr(2)Ta(2)O(7-x)N(x), which exhibited significantly increased visible light absorption and improved photocatalytic hydrogen production by 87% under solar irradiation, compared with its undoped counterpart Sr(2)Ta(2)O(7). The photocatalyst also exhibited a strong capability in photoinduced reduction of exfoliated graphene oxide (GO) to graphene sheets. By using graphene as a support for a Pt cocatalyst, a new type of composite containing graphene-Pt and Sr(2)Ta(2)O(7-x)N(x) was designed, which demonstrated an additional ∼80% increase in hydrogen production and an quantum efficiency of 6.45% (∼177% increase from pristine undoped Sr(2)Ta(2)O(7)) due to the efficient charge carrier separation on the photocatalyst. This work suggests that graphene can play an important role as an electron transfer highway, which facilitates the charge carrier collection onto Pt cocatalysts. The method can thus be considered as an excellent strategy to increase photocatalytic hydrogen production in addition to a commonly applied doping method.