Spin-polarized non-ferromagnetic surfaces for electrocatalysis: chemo-spintronics

Catalysts achieve changes in rate through modification of the free energy of adsorbed intermediates and transition states (TrS). Binding energies of intermediates and TrS are strongly correlated and modifications in catalyst composition are often ineffective in breaking these correlations, leading to minimal change in rate. Such scaling relationships are reported throughout catalysis. It is proposed that the surface spin state of a magnetic metal can change adsorption energies offering a way to overcome scaling relationships. However experimentally this approach appears reliant on the use ferromagnetic materials, limiting applicability. Here we report that transfer of ferromagnetism from a ferromagnet to an originally non-magnetic transition metal through proximity induced magnetism (PIM) via exchange interactions and/or a spin polarised current can be used to control catalytic activity. We demonstrate large changes in activity at Au and Pt electrodes for the hydrogen evolution reaction (HER). Density Functional Theory (DFT) simulations trace changes to the breaking of the scaling relationship for the Tafel HER mechanism. This occurs due to the different effects of the spin order on the vibrational zero point energy and vibrational entropy of the magnetically proximitized transition metal for intermediates and TS. The ability to circumvent scaling relationships on existing non-ferromagnetic materials can be applied across catalysis.