Unraveling the cooperative synergy of zero-dimensional graphene quantum dots and metal nanocrystals enabled by layer-by-layer assembly

Abstract

Recent years have witnessed a cornucopia of synthetic methods for fabricating carbon–metal nanocomposites. Nonetheless, achieving a cooperative synergy of zero-dimensional carbon nanomaterials and metal nanocrystals is still uncommon. To this end, we performed a controllable structural design comprising customizable alternating layers of active and functional zero-dimensional nanomaterials, which were intimately assembled together. This unique highly-ordered multilayer configuration was afforded by a judicious layer-by-layer (LbL) assembly strategy, enabling the rational and tunable construction of a series of well-defined metal/graphene quantum dots (M/GQDs)_n (M = Au, Ag, Pt) multilayers. This strategy allows the direct assembly of customized units of positively-charged graphene quantum dots (GQDs) and negatively-charged metal nanocrystals (NCs), which were integrated in an alternating stacked fashion under a pronounced electrostatic attractive interaction. Moreover, these multilayer thin films demonstrate remarkably efficient and versatile catalytic performance toward the selective organic transformation of aromatic nitro compounds, electrocatalytic methanol oxidation and photoelectrochemical water splitting under simulated solar light irradiation under ambient conditions, attributed to the cooperative synergy of the metal NC and GQD building blocks. More significantly, the catalytic performances of the (M/GQDs)_n (M = Au, Ag, Pt) multilayer thin films are tunable via the assembly cycle and sequence, as well as by selecting different metal NC types. This work highlights the significance of the customizable design of GQDs–metal-based systems for various advanced chemical-to-energy conversion applications.