Scalable synthesis of Cu2S double-superlattice nanoparticle systems with enhanced UV/visible-light-driven photocatalytic activity

•Cu2S nanoparticles with both atomic- and particle-level superlattices were obtained.•The size, shape and superlattice structures of nanoparticles were all tunable.•Highly enhanced UV/visible-light-driven photocatalytic activities were demonstrated.•Scalable synthesis was also achieved.

Size- and shape-tunable Cu2S nanoparticles were successfully synthesized via a facile one-pot solvothermal process and appreciable yields at gram-scale were achieved in every single reaction. By meticulous observation with a high resolution transmission electron microscope, intensively existing atomic-level superlattice structures were identified and perceived as a result of the coexistence of both chalcocite and chalcocite-M phase in as-obtained Cu2S nanoparticles. Further, 3D ordered self-assemblies of pristine Cu2S nanoparticles were obtained by introducing the polar solvent, ethanol, into the non-polar colloidal dispersion systems during the post-treatment process, and thereby the double-superlattice (DSL) nanoparticle systems consisted of both atomic- and particle-level superlattice structures were achieved. And as promising photocatalysts, although the photocatalytic activity was influenced mutually by the size, shape, crystallinity, atomic-level superlattice structures of pristine Cu2S nanoparticles and their self-assembling behavior, the novel structured DSL nanoparticle systems finally demonstrated highly enhanced photocatalytic efficiency towards the degradation of methylene blue.

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