No. Nootropics are not placebos and have proven their effects against placebos in clinical studies and in everyday life. As with most answers, this doesn't include all nootropics. In reality, the effects you experience will depend on the ingredients in your chosen supplement and the quality of these ingredients.
If you're careful about the ingredients in your nootropic of choice, you can avoid placebo effects altogether. For example, various placebo-controlled studies show nootropics like L-Theanine Citicoline have shown beneficial effects on memory, focus and stress-induced cognitive deficits.