El-Shall was the first to apply the Resonant Enhanced Multiphoton Ionization (REMPI) technique to selectively generate molecular ions within supersaturated host vapors and study the phenomena of ion-induced nucleation on well-defined ions. He also focused his study on the formation mechanisms of gold–zinc oxide hexagonal nanopyramids through heterogeneous nucleation using microwave synthesis. In 2018, he demonstrated nucleation and growth process of gold nanoparticles initiated by nanosecond and femtosecond laser irradiation of aqueous solutions of [AuCl4]−.