General π-electron-assisted strategy for single-atom (Ir, Pt, Ru, Pd, Fe, and Ni) electrocatalysts with bi-functional active sites toward highly efficient water splitting

Both the hydrogen evolution reaction (HER) and

the oxygen evolution reaction (OER) are crucial to water

splitting, but require alternative active sites. Now, a general pelectron-

assisted strategy to anchor single-atom sites (M=Ir,

Pt, Ru, Pd, Fe, Ni) on a heterogeneous support is reported. The

Matoms can simultaneously anchor on two distinct domains of

the hybrid support, four-fold N/C atoms (M@NC), and centers

of Co octahedra (M@Co), which are expected to serve as

bifunctional electrocatalysts towards the HER and the OER.

The Ir catalyst exhibits the best water-splitting performance,

showing a low applied potential of 1.603V to achieve

10 mAcm@2 in 1.0m KOH solution with cycling over 5 h.

DFT calculations indicate that the Ir@Co (Ir) sites can

accelerate the OER, while the Ir@NC3 sites are responsible

for the enhanced HER, clarifying the unprecedented performance

of this bifunctional catalyst towards full water splitting.