Effect of acid or alkaline catalyst and of different capping agents on the optical properties of CdS nanoparticles incorporated within a diureasil hybrid matrix

•CdS NPs with optical properties dependent on the experimental conditions.•Improved preservation of original optical properties of NPs when MPTMS is used.•Use of silyl ether ligand is affected by the sol–gel catalyst used.•The intrinsic matrix PL is affected by CdS NPs when silyl ether ligands are used.