Effect of Intrinsic Ferroelectric Phase Transition on Hydrogen Evolution Electrocatalysis

Heterogeneous electrocatalysis closely relies on the electronic structure of the catalytic materials. The ferroelectric-to-paraelectric phase transition of the materials also involves a change in the state of electrons that could impact the electrocatalytic activity, but such correlation remains unexplored. Here, we demonstrate experimentally and theoretically that the intrinsic electrocatalytic activity could be regulated as exampled by hydrogen evolution reaction catalysis over two-dimensional ferroelectric CuInP₂S₆. The obvious discontinuity in the overpotential and apparent activation energy values for CuInP₂S₆ electrode are illustrated during the ferroelectric-to-paraelectric phase transition caused by copper displacement around T_c point (318 K), revealing the ferroelectro-catalytic effect on thermodynamics and kinetics of electrocatalysis. When loading Pt single atom on the CuInP₂S₆, the paraelectric phase one showed an improved hydrogen evolution activity with smaller apparent activation energy over the ferroelectric phase counterpart. This is attributed to the copper hopping between two sulfur planes, which alternate between strong and weak H adsorption at the Pt sites to simultaneously promote H⁺ reactant adsorption and H₂ product desorption.