A click-chemical confinement strategy towards single atom copper electrocatalyst for efficient oxygen reduction reactions

Oxygen reduction reaction (ORR) is an essential process in new energy conversion systems such as fuel cells and metal air batteries. Transition metal single-atom catalysts have shown great application prospects in ORR process owing to their excellent atomic utilization and catalytic activity. However, the extremely high surface energy of individual atoms easily results in agglomeration during the preparation process. Therefore, developing novel design and synthesis methods of precursors is highly desirable to stabilize isolated metal atoms on supports under high temperatures. Here, a click-chemical confinement strategy involves Cu^I-catalyzed alkyne-azide cycloaddition (CuAAC) reaction was developed to predisperse transitional metal atoms in precursor and ensure construction of stable single atom sites after pyrolysis. Concretely, Cu^I-coordinated hyperbranched polytriazole (HPT-Cu^I) as precursor is prepared by a typical CuAAC reaction via click chemistry. Precise coordination between Cu atoms and triazole units and encapsulation of Cu atoms by polytriazole molecular chains successfully restrict Cu atoms and affording a Cu-N-C electrocatalyst. The Cu-N-C electrocatalyst deliver excellent oxygen reduction performance with a half-wave potential of 0.901 V, along with high durability. This click-chemical confinement strategy provides an alternative approach for the rational design of transition metal single-atom sites and promotes methodology on precise synthesis of advanced electrocatalytic materials.