A method of synthesis of two-dimensional (2D) nanoparticles comprises combining a first nanoparticle precursor and a second nanoparticle precursor in one or more solvents to form a solution, followed by heating the solution to a first temperature for a first time period, then subsequently heating the solution to a second temperature for a second time period, wherein the second temperature is higher than the first temperature, to effect the conversion of the nanoparticle precursors into 2D nanoparticles. In one embodiment, the first nanoparticle precursor is a metal-amine complex and the second nanoparticle precursor is a slow-releasing chalcogen source.