Boosting the oxygen reduction reaction behaviour of Ru single atoms in porous carbon nanospheres via microscopic coordination environment manipulation

The development of high-performing oxygen reduction reaction (ORR) single atom catalysts (SACs) is the basis for mass production of metal-air batteries and fuel cells. This is also an important means to achieve peak carbon dioxide emissions and carbon neutrality. Ru SACs can effectively imped Fenton reactions and significantly enhance resistance to attenuation. However, Ru SACs exhibit inferior ORR activity than TM (transition metal)-N-C catalysts and Ru atoms are prone to agglomeration. Herein, we report a simple method for the controllable preparation of Ru SAs in N and S modulated porous carbon nanospheres (Ru-SAs-N/S-PCNSs). S heteroatoms doping can change the charge density of Ru central metal atom, and reduce its binding strength to ORR intermediates, and expedite ORR activity. The porous carbon nanospheres matrix makes Ru SAs active site fully exposed. The onset potential and half-wave potential of Ru-SAs-N/S-PCNSs electrocatalyst is as high as 1.0 V and 0.87 V (vs RHE), which is in the excellent ranks. In addition, the performance of Zn-air battery with Ru-SAs-N/S-PCNSs is better than that of Pt/C + RuO2. The synthesis method we developed can effectively preclude the agglomeration of Ru metal atoms, and provides a new pathway for the preparation of SACs with high catalytic performance.