Rational design of heterogenized molecular phthalocyanine hybrid single-atom electrocatalyst towards two-electron oxygen reduction

Single-atom catalysts supported on solid substrates have inspired extensive interest, but the rational design of high-efficiency single-atom catalysts is still plagued by ambiguous structure determination of active sites and its local support effect. Here, we report hybrid single-atom catalysts by an axial coordination linkage of molecular cobalt phthalocyanine with carbon nanotubes for selective oxygen reduction reaction by screening from a series of metal phthalocyanines via preferential density-functional theory calculations. Different from conventional heterogeneous single-atom catalysts, the hybrid single-atom catalysts are proven to facilitate rational screening of target catalysts as well as understanding of its underlying oxygen reduction reaction mechanism due to its well-defined active site structure and clear coordination linkage in the hybrid single-atom catalysts. Consequently, the optimized Co hybrid single-atom catalysts exhibit improved 2e(-) oxygen reduction reaction performance compared to the corresponding homogeneous molecular catalyst in terms of activity and selectivity. When prepared as an air cathode in an air-breathing flow cell device, the optimized hybrid catalysts enable the oxygen reduction reaction at 300mAcm(-2) exhibiting a stable Faradaic efficiency exceeding 90% for 25h. Difficulties in elucidating active sites and the role of the support hamper the development of high-efficiency two-electron oxygen reduction electrocatalysts. Here, the authors develop hybrid single-atom catalysts by rational experimental and theoretical screening for hydrogen peroxide production.

Automated summary

The authors successfully design hybrid single-atom catalysts by an axial coordination linkage of molecular cobalt phthalocyanine with carbon nanotubes for selective oxygen reduction reaction. The hybrid single-atom catalysts have a well-defined active site structure and clear coordination linkage, which facilitate the rational screening of target catalysts and understanding of the underlying oxygen reduction reaction mechanism. The optimized hybrid catalysts exhibit improved 2e(-) oxygen reduction reaction performance compared to the corresponding homogeneous molecular catalyst.