Nonprecious Intermetallic Al7Cu4Ni Nanocrystals Seamlessly Integrated in Freestanding Bimodal Nanoporous Copper for Efficient Hydrogen Evolution Catalysis

Tremendous demands for renewable hydrogen generated from water splitting have stimulated intensive research on developing earth‐abundant, non‐noble, and versatile metal catalysts toward the hydrogen evolution reactions (HER). Here, self‐supported Cu‐Ni‐Al hybrid electrodes that are composed of electroactive Al7Cu4Ni@Cu4Ni core/shell nanocrystals seamlessly integrated in self‐supported 3D bimodal nanoporous Cu skeleton (Bi‐NP Cu/Al7Cu4Ni@Cu4Ni) as robust HER electrocatalysts in alkaline electrolyte are reported. As a result of the proper architecture, in which the Bi‐NP Cu skeleton not only facilitates both electron and electrolyte transports but also provides high specific surface areas to fully use high electrocatalytic activity of Al7Cu4Ni@Cu4Ni core/shell nanocrystals, the Bi‐NP Cu/Al7Cu4Ni@Cu4Ni hybrid catalysts exhibit a low onset overpotential of 60 mV and a small Tafel slope of 110 mV dec−1, enabling the catalytic current density of 10 mA cm−2 at a low overpotential of 139 mV. The highly stable electrochemical performance makes them promising candidates as cathode catalysts in alkaline‐based devices. Self‐supported bimodal nanoporous Cu‐Ni‐Al catalytic electrodes are successfully developed as robust hydrogen evolution reaction (HER) electrocatalysts in alkaline electrolyte. These hybrid electrodes that are composed of electroactive Al7Cu4Ni@Cu4Ni core/shell nanocrystals seamlessly integrated in a 3D bimodal nanoporous Cu skeleton (Bi‐NP Cu/Al7Cu4Ni@Cu4Ni) exhibit exceptional HER performance as a result of enhanced electrolyte accessibility and electron transport as well as HER catalytic activity.