{Co4O4} Cubanes in a conducting polymer matrix as bio-inspired molecular oxygen evolution catalysts
Shangkun Li, Zeyi Zhang, Walker R. Marks, Xinan Huang, Hang Chen, Dragos Stoian, Rolf Erni, Carlos A. Triana, Greta R. Patzke
Abstract
Exploration of efficient molecular water oxidation catalysts for long-term application remains a key challenge for the conversion of renewable energy sources into fuels. Cuboidal {Co4O4} complexes keep attracting interest as molecular water oxidation catalysts as they combine features of both heterogeneous and homogeneous catalysis with bio-inspired motifs. However, the application of many cluster-based catalysts for the oxygen evolution reaction still requires new stabilization strategies. Drawing inspiration from the stabilizing effects of natural polymers, we introduce a conductive polymer-hybrid approach to covalently immobilize {Co4O4} cubane oxo clusters as oxygen evolution catalysts. Polypyrrole is applied as an efficient p-type conducting polymer that promotes hole transfer during the oxygen evolution reaction, resulting in higher turnover frequency compared to the pristine {Co4O4} oxo cluster and heterogeneous Co-oxide benchmarks. The asymmetric coordination of {Co4O4} not only mitigates catalyst decomposition pathways, but also increases the catalytic efficiency by exposing a directed cofacial dihydroxide motif during catalysis. Cuboidal {Co4O4} complexes are attractive molecular water oxidation catalysts as they combine features of both heterogeneous and homogeneous catalysis with bio-inspired motifs, but their application requires stabilization strategies. Here, the authors introduce a conductive polymer-hybrid approach to covalently immobilize {Co4O4} clusters.