Constructing built-in electric field in crystalline-amorphous heterostructure bifunctional electrocatalysts for highly efficient overall water splitting at high current density
Exploring efficient bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions is key to water electrolysis. However, the inherently slow reaction kinetics of electrocatalysis are constrained by mass transfer limitations and unsuitable adsorption/desorption dynamics. Herein, a Fe-doped-Ni3S2/NiFeCoCeIn oxide hydroxide (FNS/HEOXY) crystalline–amorphous heterostructure electrocatalyst with a large work function difference (ΔΦ) and strong built-in electric field (BEF) is successfully designed and synthesized. Benefiting from the electron transfer behavior from FNS to HEOXY, the FNS/HEOXY shows outstanding catalytic activity for both hydrogen and oxygen evolution, along with ultra-high stability in an alkaline medium at an industrial-level current density. Moreover, the anion exchange membrane water electrolyzer (AEMWE) assembled by the FNS/HEOXY requires only a minimal cell voltage of 1.83 V to reach 1 A cm−2 at 80 °C. Both experimental and theoretical results confirm the interfacial charge redistribution induced by the strong BEF, thus finely optimizing the adsorption energy. This work proposes a new design principle toward efficient electrocatalysts for energy conversion.