The emergence of single-atom catalysis (SACs) not only paves a path for creating a new type of heterogeneous catalysts that combines high activity and economic utilization of transition metal atoms, but also provides a promising architecture of catalyst that can fuse advantages of conventional heterogeneous and homogeneous catalysts . In the past decade, with the aid of sophisticated experimental techniques and computational tools, scientists have made substantial progress in both crafting wellcontrolled structures and understanding the working mechanisms of SACs . There is no doubt that the local environment around metal centers in SACs plays a crucial part in shaping their electronic structures and ensuing catalytic activity and selectivity , including the coordinating atoms of metal centers , the multi-adsorption effects , and the strength of metal-support interaction . While most of these studies have primarily focused on the first coordination layer , much less attention has been paid to the secondary and even more distant coordination shells of metal centers in SACs. Meanwhile, in enzymatic and homogeneous catalysis, the secondary coordination shell is known to play an important role in determining the performance of the catalyst of interest . Even though SACs may share some similarity with molecular catalysts regarding to the structures of active centers, and some earlier work has shown the cooperation of two adjacent active sites , there has been little computational investigation exclusively on the secondary coordination effects in SACs.