Ammonium Salts: New Synergistic Additive for Chemical Vapor Deposition Growth of MoS 2 .

Controllable and scalable fabrication is the precondition for realizing the large number of superior electronic and catalytic applications of MoS 2 . Here, we report a new type of synergistic additives, ammonium salts, for chemical vapor deposition (CVD) growth of MoS 2 . On the basis of the catalysis of ammonium salts, we can achieve layer and shape-controlled MoS 2 domains and centimeter-scale MoS 2 films. Compared to frequently used alkali metal ions as the catalysts, ammonium salts are decomposed completely at low temperature (below 513 °C), resulting in clean and nondestructive as-grown substrates. Thus, MoS 2 electronic devices can be directly fabricated on them, and the redundant transfer step is no longer needed. This method can also promote the direct growth of MoS 2 on the conductive substrate and boost the improvement of hydrogen evolution reaction (HER) performance. The ammonium salt-mediated CVD method will pave a new way for MoS 2 toward real applications in modern electronics and catalysis.