Harmonious Heterointerfaces Formed on 2D‐Pt Nanodendrites by Facet‐Respective Stepwise Metal Deposition for Enhanced Hydrogen Evolution Reaction

The performance of nanocrystal (NC) catalysts could be maximized by introducing rationally designed heterointerfaces formed by the facet‐ and spatio‐specific modification with other materials of desired size and thickness. However, such heterointerfaces are limited in scope and synthetically challenging. Herein, we applied a wet chemistry method to tunably deposit Pd and Ni on the available surfaces of porous 2D−Pt nanodendrites (NDs). Using 2D silica nanoreactors to house the 2D‐PtND, an 0.5‐nm‐thick epitaxial Pd or Ni layer (e‐Pd or e‐Ni) was exclusively formed on the flat {110} surface of 2D−Pt, while a non‐epitaxial Pd or Ni layer (n‐Pd or n‐Ni) was typically deposited at the {111/100} edge in absence of nanoreactor. Notably, these differently located Pd/Pt and Ni/Pt heterointerfaces experienced distinct electronic effect to influence unequally in electrocatalytic synergy for hydrogen evolution reaction (HER). For instance, an enhanced H2 generation on the Pt{110} facet with 2D‐2D interfaced e‐Pd deposition and faster water dissociation on the edge‐located n‐Ni overpowered their facet‐located counterparts in respective HER catalysis. Therefore, a feasible assembling of the valuable heterointerfaces in the optimal 2D n‐Ni/e‐Pd/Pt catalyst overcame the sluggish alkaline HER kinetics, with a catalytic activity 7.9 times higher than that of commercial Pt/C. 2D‐Metal Nanohybrids with harmonious heterointerfaces have been synthesized by facet‐respective stepwise metal deposition. These hybrid nanomaterial can approach superior electrocatalytic hydrogen evolution reaction performance induced by unique multi heterointerfaces in specific facet for effective activation of platinum.