3. A mixture of ethylene glycol (1 mL) and high-purity (NH4)2MoS4 (0.01 g) was ultrasonically treated for 20 min until they entirely dissolved, then the (NH4)2MoS4 solution was spin-coated onto the Au NP samples using a spinner with a rotation speed of 2000 rpm for 3 min. 4. ...