Transition Metal Atoms Supported by a NbSSe Monolayer for Electrocatalytic Oxygen Reduction/Evolution Reactions

We suggest how to develop high-performance, low-cost,
and stable
oxygen evolution reaction (OER) and oxygen reduction reaction (ORR)
catalysts that may be relevant in the hydrogen economy. Transition
metal dichalcogenides (TMDs) have great potential for electronics,
photonics, catalysis, energy storage, and energy conversion due to
their unique properties and structures. By using first-principles
calculations, a series of single-atom catalysts (SACs) employing transition
metal atoms adsorbed on a NbSSe monolayer are investigated jointly
with the catalytic activity of TM@NbSSe for the ORR and OER. By stability
and catalytic performance screening, Co@NbSSe is shown to have excellent
ORR and OER activities irrespective of the Co atom being adsorbed
on the S-edge or Se-edge of NbSSe, with the overpotential in the S-edge
being 0.41 V (ORR) and 0.42 V (OER), while in the Se-edge, such values
are 0.40 V (ORR) and 0.46 V (OER). It is also found that the Fe atom
adsorbed on the Se-edge of NbSSe shows excellent bifunctional activity
with overpotentials of 0.35 V (ORR) and 0.36 V (OER). Moreover, the
Ni atom adsorbed on the S-edge of NbSSe showed a high OER performance
with an overpotential of 0.46 V. Additionally, according to the linear
relationship of intermediates, volcano plots are reported to describe
the activity trends of the OER and ORR on TM@NbSSe. Scaling relationship
between
the d-band center and adsorption energy of the intermediates is also
established to reveal the catalytic origin, with suitable d-band centers
leading to moderate adsorption strength, all this being of relevance
to attain good catalytic performances. Finally, the origin of the
activity is elucidated by introducing as a descriptor the novel physical
quantity φ, which is based on the intrinsic properties of the
TM atoms.