Determining the electrochemical activation mechanism of Prussian blue analog precatalysts for a high-efficiency oxygen evolution reaction
Wei Hua, Huanhuan Sun, Yueying Li, Yuxin Zhang, Jian‐Gan Wang
Abstract
Prussian blue analogues (PBAs) are regarded as effective pre-catalysts for oxygen evolution reaction (OER), but the underlying mechanism of their electrochemical activation is still not well elucidated. In this work, we design and construct PBAs-based pre-catalysts to unveil the activation mechanism and achieve high-efficient OER. The PBAs undergo <em>in situ</em> electrochemical transformation to form the corresponding metal (oxy)hydroxides (M(O)OH) as the true OER catalyst. More importantly, the hexacyanoferrate ligands are unveiled to experience repetitive interfactial coordination/etching with/from the M(O)OH during the activation process. The distinct mechanism could achieve <em>in situ</em> Fe doping and the increase of defect concentration. The defect-enriched Fe-NiOOH derived from a well-designed NiHCF/Ni(OH)<sub>2 </sub>pre-catalyst requires a low overpotential of 227 mV to drive the current density of 10 mA cm<sup>-2</sup>, and could work stably at 130 mA cm<sup>-2</sup> over 100 h. This work offers a fundamental insight into the activation mechanism for developing advanced pre-catalysts for OER.