LaFeO3 meets nitrogen-doped graphene functionalized with ultralow Pt loading in an impactful Z-scheme platform for photocatalytic hydrogen evolution

Abstract

Recently, Z-scheme systems have gained immense attention for photocatalytic hydrogen evolution (PHE). Herein, LaFeO3 perovskite (as photosystem II) was shelled by nitrogen-doped graphene (NGr as photosystem I) functionalized with ultralow Pt loading to produce an impactful and stable ternary Z-scheme platform: LaFeO3@NGr-Pt. Under visible-light irradiation, the LaFeO3@NGr(3)-Pt-0.5 entity (a NGr shell thickness of 3 nm and Pt loading of 0.5 wt%) delivered a PHE performance of 3.52 mu mol mg(cat)(-1) h(-1), superior to those of binary LaFeO3@NGr(3) (1.86 mu mol mg(cat)(-1) h(-1)), NGr-Pt-0.5 (0.88 mu mol mg(cat)(-1) h(-1)), and free-standing NGr (0.34 mu mol mg(cat)(-1) h(-1)) catalysts. It also showed outstanding PHE performance compared to previous advanced Z-scheme species. In addition, the ternary Z-scheme system exhibited a high maximum apparent quantum yield of 18.25% at 450 nm. This excellent performance of the Z-scheme platform can be attributed to the following. (i) The interfacial contact between LaFeO3 and NGr facilitated charge carrier transfer under light. (ii) The promising direct Z-scheme platform not only preserved the strong redox potentials of the two photosystems but also inhibited charge recombination significantly. (iii) Finally, the Pt cocatalyst attracted the electrons migrating from NGr and assisted the adsorption of hydrogen atoms, thus accelerating the overall catalytic reaction.