Revealing the Role of Electrocatalyst Crystal Structure on Oxygen Evolution Reaction with Nickel as an Example.

Establishing a correlation between the crystal structure and electrocatalytic activity is crucial to the rational design of high performance electrocatalysts. In this work, taking the widely investigated nickel (Ni) based nonprecious oxygen evolution reaction (OER) catalyst as an example, for the first time, it is reported that the crystal structure plays a critical role in determining the OER performance. Similar-sized nickel nanoparticles but in different hexagonal close-packed phase and face-centered cubic phase coated with N-doped carbon shells, noted as hcp-Ni@NC and fcc-Ni@NC, are successfully prepared, respectively, in which the N-coated carbon shell structures were also similar. Surprisingly, a dramatically enhanced OER performance of hcp-Ni@NC in comparison with fcc-Ni@NC is observed. The hcp-Ni@NC only requires 305 mV overpotential to achieve the current density of 10 mA cm-2 , which is 55 mV lower than that of fcc-Ni@NC, which can be ascribed to the influence of nickel crystal phase on the electron structure of N-doped carbon shell. This finding will bring new thinking toward the rational design of high performance non-noble metal electrocatalysts.