Two-Dimensionally Assembled Pd–Pt–Ir Supernanosheets with Subnanometer Interlayer Spacings toward High-Efficiency and Durable Water Splitting

Orderly assembled supernanosheets (ASNSs), integrating the architectural features of subunit NSs, 2D subnanometer interlayer spacings, and multiple electroactive sites, can remarkably expand the functionality and stability of 2D multimetallic nanomaterials. Here, we report a versatile template-directed strategy for synthesizing multimetallic ASNSs. As a proof-of-concept, ternary Pd44Pt30Ir26 ASNSs are elaborately synthesized and applied as robust bifunctional electrocatalysts toward overall water splitting. The products are mesocrystalline 2D superstructures derived from lamellar stacking of ultrathin Pd–Pt–Ir NSs. During electrocatalysis, the multilayered superstructures can locally concentrate reactants within the parallel subnanometer interlayer spacings and essentially intensify the morphological stability. Featured with electronically modulated Pt–IrOx dual active sites, the products exhibit high efficiency and durable bifunctional electrocatalytic activity for overall water splitting in 1.0 M KOH, presenting 46 and 92 mV lower overpotential than the state-of-the-art Pt/C and Ir/C for hydrogen evolution and oxygen evolution reactions, respectively. Significantly, they can realize stable H2 production at a large current of 500 mA in an anion exchange membrane electrolyzer. This work fully proves that the integration of an ordered 2D superstructure and electronic-modulated multiple reactive sites has broad prospects for advanced electrocatalysts.