COHERON · Confined Electrochemical Cells for Activity Improvement of Nickel in the Hydrogen Evolution Reaction

Electrocatalytic water splitting via the hydrogen evolution reaction (HER) has emerged as a promising route for green hydrogen production. While platinum remains the benchmark catalyst for HER, its scarcity and high cost hinder large-scale deployment. Earth-abundant nickel offers a pragmatic alternative, yet it lags behind platinum by tens of millivolts in overpotential and suffers from bubble accumulation, limiting its overall activity. Some studies report that the spatial confinement of catalyst particles can yield multi-fold enhancement in catalytic activity. These studies typically impose confinement through fixed geometries and infer mechanisms indirectly from bulk electrochemistry, leaving key questions unresolved—such as whether the enhanced activity arises from changes in local chemistry or gas dynamics.COHERON proposes a systematic investigation of HER in confined electrochemical cells, where the cell volume will be precisely tuned from micro- to nanoliters to isolate the effects of spatial confinement on catalytic response. Two complementary microscopy techniques will be integrated with physics-based modeling to capture both activity and underlying mechanisms. Scanning Electrochemical Cell Microscopy will map reaction activity as a function of cell volume; in-situ liquid-cell electrochemical transmission electron microscopy will track nickel nanoparticle restructuring and H2 bubble dynamics; and finite-element modeling will disentangle the contributions of ion transport, local chemistry, and geometry. The outcome will be a controlled, visual, and predictive framework for exploiting confinement to enhance nickel-based HER by establishing quantitative links between cell volume, geometric parameters, and catalytic behavior. By improving green hydrogen production and reducing reliance on critical raw materials, this outcome will contribute to the EU’s climate goals and help democratize access to clean hydrogen energy.