Shape-controlled synthesis of Ni nanocrystals via a wet-chemistry strategy and their shape-dependent catalytic activity

Shape-controlled synthesis of non-noble metal nanocrystals (NCs) is vital to their catalysis applications due to their different exposed surfaces and atomic coordination environments. Here, we report a facile synthesis of Ni nanocubes and cuboctahedra with controlled shapes and high yields via a wet-chemistry strategy. The key to success relies on the use of cetyltrimethyl ammonium bromide (CTAB), formaldehyde (HCHO) and a specific reaction temperature, which could effectively cap the desired surface and tune their growth rate. Specifically, nanocubes switched to cuboctahedra and octahedra with an increased reaction temperature due to gradual CO desorption from the surfaces of NCs. Meanwhile, it should be worth noting that CTAB and the generated CO molecules through HCHO decomposition would co-adsorb on the {100} facets of Ni NCs. As a proof-of-application, the obtained Ni NCs exhibited high activity in the oxygen evolution reaction (OER) with over-potentials of 383 mV and 402 mV for nanocubes and cuboctahedra at a current density of 10 mA cm−2, respectively, demonstrating that the {100} facets are more favorable toward OER. These results suggested that their performance is strongly shape dependent and is derived from different surface energies and active sites.