Colloidal synthesis of AgGa(S1−xSex)2 solid solution nanocrystals with composition-dependent crystal phase for efficient photocatalytic degradation of methyl violet

Abstract

A series of homogeneous AgGa(S_1−xSe_x)₂ solid solution nanocrystals with controllable composition (0 ≤ x ≤ 1) have been successfully prepared through a facile colloidal synthesis approach. Remarkably, they exhibit an evident crystal phase transformation from orthorhombic to tetragonal along with the chemical composition of particles from either S or Se excess to S/Se approximate equality. The factors to determine this phase-selective synthesis of AgGa(S_1-xSe_x)₂ nanocrystals could be probably attributed to the relatively weak reactivity of Ga³⁺ in the oleylamine-based reactive system and the metastable terminal possessed by AgGa(S_1-xSe_x)₂, which was proposed after investigating their nucleation mechanisms. Furthermore, the photocatalytic potential of the as-synthesized AgGa(S_1−xSe_x)₂ nanocrystals has been evaluated through degrading methyl violet under visible-light illumination. Benefiting from the optimized crystal phase and energy structure, AgGa(S_0.7Se_0.3)₂ presents the optimal photocatalytic efficiency of 88.48%.