From Quinary Co–Cu–Mo–Pd–Re Materials Libraries to Gas Diffusion Electrodes for Alkaline Hydrogen Evolution

Abstract Developing a hydrogen evolution reaction (HER) electrocatalyst that can steadily drive a large current density is of great significance for industrial electrochemical water‐splitting technology. Herein, the compositionally complex noble‐metal‐lean system Co–Cu–Mo–Pd–Re is investigated for alkaline HER by a scanning droplet cell‐assisted high‐throughput screening of co‐sputtered thin‐film material libraries. The identified hit compositions are used to prepare a catalyst‐coated Ni foam‐based layer that is hot‐pressed with a specifically designed PEEK‐covered carbon‐based gas diffusion layer to obtain a novel‐design gas diffusion electrode (GDE). H 2 bubbles that collect on the electrode surface are effectively reduced by controlling the hydrophobicity of the catalyst layer of the GDE, hence enabling a high current (−1 A cm −2 ) operation for HER in alkaline water electrolysis.