Template‐assisted Morphological Evolution of Cu₂S and Cu₂MoS₄ from Octahedral Cu₂O Crystals

Abstract

Various morphologies of Cu 2 S and Cu 2 MoS 4 were synthesized from an octahedral Cu 2 O template in the presence of various concentrations of sodium molybdate and thioacetamide by carrying out solvothermal reactions in an ethylene glycol solvent. The morphology varied from hollow octahedral Cu 2 S structures, through small pieces of P-Cu 2 MoS 4 , and finally to thin square-like plates of I-Cu 2 MoS 4 , depending on the concentrations of sodium molybdate and thioacetamide. The XRD data indicated that the Cu 2 MoS 4 structural phases changed from P42m to I42m the concentrations of sodium molybdate and thioacetamide increased.

Sliding Modulation in Nonlinear Optical Effect in Two-Dimensional van der Waals Cu2MoS4

“…We emphasize that, unlike MoS 2 , ,, which is centrosymmetric in even layers (when adopting 2H stacking type), Cu 2 MX 4 phases are intrinsically noncentrosymmetric and can produce enhanced SHG effects with increasing thickness. Importantly, Cu 2 MX 4 may undergo a polymorph transformation between two stable stacking phases (namely, P and I phases) distinguished by a (1/2, 1/2, 0) layer shift, which is indeed observed under mild conditions during synthesis, ,,, suggesting the presence of a small energy barrier in interlayer sliding. Although in the Cu 2 MX 4 family the pure single layer or bilayer by exfoliation is still a challenge, it has been observed that the Cu 2 MX 4 nanosheets with a thickness of about 1.0 nm (close to the bilayer thickness) obtained by ion intercalation or ultrasonication do maintain the same stacking patterns as the bulk P/I phases. , Therefore, we foresee that bilayer or multilayer Cu 2 MX 4 may become a novel vdW NLO system to generate sliding-modulated SHG signals.…”