Fig. 2. Growth mechanism of the PC structure. (a) A cartoon image illustrating the morphology evolution. (b) Small clusters can be obtained immediately after adding TAA/OAm solution into Ni(NO3)2/OAm. (c) Products obtained after increasing the temperature to 180 °C. (d) Products obtained after keeping the reaction temperature at 180 °C for 30 min. (e) Products obtained with a reaction temperature of 140 °C for 4 h.
