Investigating the Dynamic Role of Iron in Activating Nickel-Iron-Layered Double Hydroxide During the Oxygen Evolution Reaction: An Operando

Nickel-iron layered double hydroxides (NiFe-LDHs) are highly effective oxygen evolution reaction (OER) electrocatalysts, undergoing dynamic transformations into active oxyhydroxides under electrochemical conditions. However, the structural and electronic changes during this process remain unclear, requiring real-time monitoring on short timescales (milliseconds to seconds). A key aspect of this transformation is the interplay between Fe oxidation and deprotonation, where Fe⁴⁺ may induce Ni-OH deprotonation or Ni oxidation may first weaken the OH network, triggering deprotonation and Fe activation (Fe3⁺→Fe4+). To resolve these ambiguities, we propose to operando study NiFe-LDHs using synchrotron Mössbauer spectroscopy (SMS) at ESRF’s ID14. Additionally, we aim to investigate Fe’s role in the α-to-γ phase transition, crucial for optimizing catalytic performance. Understanding Fe’s role in structural evolution is significant to NiFe catalyst stability and efficiency.