Rational Design and Synthesis of a Nanostructured Electrochemical Reactor for Alkaline Hydrogen Evolution Reaction Electrode

ABSTRACT Green hydrogen production driven by intermittent renewable energy poses significant challenges to alkaline hydrogen evolution reaction (HER) in achieving high‐efficiency and durability. An all‐in‐one nanostructured electrochemical reactor (NER) was newly designed and synthesized for the HER electrode to tackle the challenges by enabling continuous electron transport and intensified gas‐liquid transport in NER, thereby maximizing the interfacial charge‐transfer reaction capability of the catalyst electrode under large and varying currents. This was realized by designing an all‐in‐one catalyst P‐CoPt 3 /P‐CoMoO 4 , featuring a self‐supported structure, a heterostructure, and a super‐hydrophilic nanoarray. This all‐in‐one catalyst functions as a built‐in NER with finely‐tailored critical interfaces. Self‐supported structure and heterostructure form strong couplings at electron‐conducting heterointerfaces, enabling continuous electron transport across these interfaces and thus in the NER. Super‐hydrophilic nanoarray allows continuous gas‐liquid transport at electrode/electrolyte interfaces, intensifying the gas‐liquid transport process in the NER. Consequently, P‐CoPt 3 /P‐CoMoO 4 displayed a >30‐fold increase in mass activity for alkaline HER compared to the P‐CoPt 3 catalyst electrode. It exhibited an impressively low overpotential of 132 mV at 1 A cm −2 . Stable operation for over 750 h at 100 and 500 mA cm −2 and notable durability under varying currents were also obtained. Overall water‐splitting of P‐CoPt 3 /P‐CoMoO 4 || RuO 2 outperformed the commercial Pt/C || RuO 2, especially at higher currents.