Water Reduction Reaction in the Presence of a Nickel–Iron Metal–Organic Framework: A Case Study

Metal–organic frameworks (MOFs) have garnered significant interest as catalysts for water splitting. However, their stability under the hydrogen evolution reaction (HER) remains relatively unexplored. This study examined the stability of Ni–Fe MOF featuring 1,4-benzene dicarboxylate (1,4-BDC) linkers as (pre)catalysts for HER. Various analytical techniques, especially electrochemical analysis, X-ray absorption spectroscopy (XAS), and scanning electron microscopy (SEM), were employed to elucidate the MOF’s behavior during HER. These methods revealed the transformation of the MOF surface into a metal (hydr)oxide, which acts as the active catalyst for the HER. SEM confirmed significant morphological restructuring of the Ni–Fe MOF surface after HER conditions. These experiments provide new insights into the structural evolution of Ni–Fe MOFs under HER conditions, addressing a critical gap in understanding the stability of MOFs as electrocatalysts. Unlike previous works that primarily focused on catalytic performance, our investigation highlights the transformation pathways of MOFs, revealing their role as precatalysts rather than stable catalysts. Our findings emphasize the necessity of re-evaluating MOFs’ stability under reductive conditions, opening new avenues for the design of more durable MOF-based electrocatalysts.