Plasmonic Au nanoclusters dispersed in nitrogen-doped graphene as a robust photocatalyst for light-to-hydrogen conversion

Supported plasmonic Au nanoclusters (NCs) consisting of a few tens of atoms can potentially offer great advantages for the light-driven hydrogen evolution reaction (HER). Here, we report on the synthesis of well-dispersed and stable plasmonic Au NCs of 0.5-1.0 nm size on nitrogen-doped high surface area graphene (N-Gr)viafreeze-drying and pyrolyzing in argon. The Au NCs/N-Gr photocatalyst exhibits under visible-light an impressive HER achievement (3.16 μmol mg_cat⁻¹h⁻¹) compared to Au single atoms/N-Gr (2.06 μmol mg_cat⁻¹h⁻¹) and Au nanoparticles (20 nm size)/N-Gr (0.92 μmol mg_cat⁻¹h⁻¹), with a maximum apparent quantum yield of 14.30%. These performances are synergistically attributed to two effects: (a) the strong surface plasmon resonance stimulated by light absorption and transferred near the surface of Au NCs, where the N-Gr conductive support can prolong the plasmon-produced hot electrons and direct the light-to-hydrogen conversion; (b) a high catalytic efficiency of Au NCs/N-Gr nanocomposites.