Surface Engineering of Defective and Porous Ir Metallene with Polyallylamine for Hydrogen Evolution Electrocatalysis

The design of defects and porous structures into metallene with functional surfaces is highly desired to improve its permeability, surface area, and active sites, but remains a great challenge. In this work, polyallylamine-encapsulated Ir metallene with defects and porous structure (Ir@PAH metallene) is easily fabricated by a one-step wet chemical reduction method. The Ir@PAH metallene exhibits excellent hydrogen evolution reaction (HER) performance with an overpotential of only 14 mV at 10 mA cm^-2 , a low Tafel slope of 31.2 mV dec^-1 , and almost no activity decay after stability test. The abundant defects and pores as well as several-atomic-layer nanosheet structures of Ir@PAH metallene provide a large specific surface area, high conductivity, and efficient mass transport/diffusion. In addition, surface-functionalized PAH molecules can modulate the electronic structure through strong Ir-N interaction and act as proton carriers to capture hydrogen ions, which is very beneficial for the HER in acidic media. This work provides a useful strategy for the synthesis of the defective and porous metallene with functionalized surfaces for various catalytic applications.