  Current research efforts on single-atom catalysts (SACs) exclusively focus on
nonmetal or transition-metal atoms as active centers, while employing
main-group metal elements is seemingly excluded because their delocalized
s/p-bands are prone to yield a broadened resonance for the interaction with
adsorbates. Here, we use high-throughput first-principles calculations to
investigate the possible incorporation of Mg, Al and Ga to form graphene-based
SACs for NO reduction reaction (NORR) toward NH3. 51 SAC candidates with
different metal coordination environment have been computationally screened
employing a rationally designed four-step process, yielding six SACs with high
catalytic activity and NORR selectivity. The performance is rationalized by the
modulation of s/p-band filling of the main-group metals. The adsorption free
energy of NO is identified as efficient descriptor for such SACs. The
underlying physical mechanism is revealed and generally applicable to other
main group metal SACs. These fundamental insights extend SACs to main-group
metal elements.
