posted on 2023-01-06, 19:07authored byHongqiang Jin, Peixin Cui, Changyan Cao, Xiaohu Yu, Runqing Zhao, Ding Ma, Weiguo Song
Regulating
the density of metal single atoms and exploring the
interaction among them are showing great potential to further raise
the performance of single-atom catalysts (SACs). Herein, we produce
a series of Cu SACs with densities ranging from 0.1 to 2.4 atoms/nm2 and find that the catalytic activity is proportional to Cu
single-atom density in the benzene hydroxylation reaction. Mechanistic
studies reveal that the interactions among neighboring single-atom
moieties in ultra-high-density Cu SAC alter the electronic structures
of Cu single atoms, resulting in stronger •OH adsorption,
which is beneficial for the benzene hydroxylation reaction by suppressing
the O2 formation side reaction. The adsorption energy of
hydroxyl radicals is further proposed and verified as a key descriptor
to explain the reaction differences of Cu SACs with various densities.
As a result, the ultra-high-density Cu SAC of 2.4 atoms/nm2 (21.3 wt %) exhibits maximum mass specific activity and H2O2 utilization efficiency, which are both significantly
higher than the reported results in the literature and solved the
key challenges of SACs in the benzene hydroxylation reaction. This
study sheds light on how the SAC density affects active sites and
offers a practical catalyst for phenol production by the H2O2 route.