Abstract: Disclosed herein are methods and systems for thinning a transition metal dichalcogenide. The methods comprise: illuminating the transition metal dichalcogenide material with electromagnetic radiation while applying a positive potential between the transition metal dichalcogenide material and a gate electrode; wherein the electromagnetic radiation has an energy that is less than the energy of the direct band gap and greater than or equal to the energy of the indirect band gap of the transition metal dichalcogenide material; thereby: promoting electrons from the valence band to the conduction band of the indirect band gap of the transition metal dichalcogenide material and decreasing the thickness of the transition metal dichalcogenide via electrochemical degradation. The methods disclosed herein are self-limiting.