Mn-doping tuned electron configuration and oxygen vacancies in NiO nanoparticles for stable electrocatalytic oxygen evolution reaction

Manipulating the electronic configuration of electrocatalysts through doping strategies is crucial for the development of preeminent non-precious metal electrocatalysts for oxygen evolution reaction (OER). In this work, Mn-doping NiO nanoparticles with oxygen (O) vacancies (denoted as Mn-NiO-Ov) are synthesized by calcinating the two-dimensional Ni-Mn layered double hydroxides (LDHs) precursors at specific temperatures. Magically, as revealed by structural characterizations and first-principle quantum chemical computations, Mn-doping causes a modification in the electronic structure through the electron transfer from Ni to Mn via O bridges and the modified eg orbital of Ni led by charge transfer is of benefit to the adsorption of O species on Ni sites in Mn-NiO-Ov and promoting the intrinsic metallic property of NiO nanoparticles. Furthermore, it is illustrated that the Mn-NiO-Ov nanoparticles can achieve a lower overpotential of 265 mV at the current density of 10 mA cm−2, and a Tafel slope of 61.3 mV dec−1 under alkaline media. More importantly, the Mn-NiO-Ov nanoparticles show also great stability (98.2%) after 50 h continuously test far more than pure NiO nanoparticles (62.1%). This research provides the theoretical principle for the promotion of electrocatalysts OER activity and stability by doping foreign metal to tune electron configuration.