Remote Synergy between Heterogeneous Single Atoms and Clusters for Enhanced Oxygen Evolution.

Integrating single atoms and clusters into one system is a novel strategy to achieve desired catalytic performances. Compared with homogeneous single-atom cluster catalysts, heterogeneous ones combine the merits of different species and therefore show greater potential. However, it is still challenging to construct single-atom cluster systems of heterogeneous species, and the underlying mechanism for activity improvement remains unclear. In this work, we developed a heterogeneous single-atom cluster catalyst (CoIr/N-C) for efficient oxygen evolution. The Ir single atoms worked in synergy with the Co clusters at a distance of about 8 Å, which optimized the configuration of the key intermediates. Consequently, the oxygen evolution activity was significantly improved on CoIr/N-C relative to the Co cluster catalyst (Co/N-C), exhibiting an overpotential lower by 107 mV than that of Co/N-C at 10 mA cm and a turnover frequency 50.9 times as much as that of Co/N-C at an overpotential of 300 mV.