Ir Single Atom-Doped Ni₂P Anchored by Carbonized Polymer Dots for Robust Overall Water Splitting

Developing high-performance bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is imperative in facilitating large-scale production of hydrogen. Herein, we develop an atomically dispersed catalyst, Ir-Ni2P/CPDs, in which iridium single atoms are dual-anchored by both carbonized polymer dots (CPDs) and Ni2P. CPDs serve as electronic bridges, which facilitate the construction of high-density oxygen bridge structures, leading to high loading of isolated Ir atoms that act as the principal active sites for HER and OER. The resultant Ir-Ni2P/CPD catalyst demonstrates low overpotentials of only 25 +/- 1 and 240 +/- 2 mV at 10 mA cm(-2) for HER and OER in 1.0 M KOH solution, respectively, surpassing those of commercial Pt/C and IrO2 catalysts. Moreover, it exhibits robust long-term catalytic stability. The experimental and theoretical results demonstrate that the bonding environment of dual-anchored isolated Ir sites plays an essential role in optimizing the adsorption and desorption kinetics of hydrogen/oxygen intermediates. This work extends a strategy for the design of high-loaded metal single-atom electrocatalysts for greatly facilitating HER and OER activities.