In situ self-reconstruction and oxygen evolution reaction mechanism study of Ni-Fe-V hydroxide synthesized by electrodeposition

In the oxygen evolution reaction (OER), the lattice oxygen mechanism (LOM) has the potential to exceed the theoretical overpotential limit of approximately 370 mV associated with the traditional adsorbate evolution mechanism (AEM). Therefore, it is crucial to promote lattice oxygen involvement in the OER through careful design. We prepared a self-supported NiFeV hydroxide pre-catalyst electrode using a one-step electrochemical deposition method. Most of the V in the pre-catalyst dissolved during electrochemical activation, as confirmed by various ex situ and in situ characterization studies. The actual catalyst comprised V-doped FeOOH and NiOOH. Notably, significant oxygen vacancies were generated due to V element dissolution and leaching. The reconstructed catalyst can facilitate oxygen production via both the AEM and LOM, supported by theoretical calculations and experimental validation. It operates steadily for 750 hours at a current density of 50 mA cm-2, requiring only 200 mV and 253 mV overpotentials to achieve current densities of 10 mA cm-2 and 100 mA cm-2, respectively. This work elucidates the electrochemical reconstruction of V-containing hydroxides in alkaline media under anodic conditions while providing valuable insights into developing high-performance catalysts that involve the LOM.