Synthesis and Characterization of a Covalent Porphyrin-Cobalt Diimine-Dioxime Dyad for Photoelectrochemical H2 Evolution

The utilization of solar energy via photoelectrochemical cells (PEC) towards hydrogen (H-2) production is a promising approach in the field of artificial photosynthesis. In this work, the synthesis and complete characterization of the first covalently linked porphyrin-cobalt diimine-dioxime dyad (ZnP-Co) is reported. The synthetic procedure that was followed is based on simple and high yielding reactions, without using any noble metal. Photophysical investigation of the dyad revealed sufficient electronic communication between the sensitizer and the catalyst in the excited state. Finally, NiO films were sensitized with ZnP-Co and the H-2-evolving photoelectrochemical activity of the resulting photocathode was assessed. The modest performances could be rationalized thanks to photolysis and post-operando characterizations of the system, thus providing some guidelines toward the design of more efficient porphyrin-based assemblies.

Automated summary

This study reports the synthesis and full characterization of the first covalently linked porphyrin-cobalt diimine-dioxime dyad (ZnP-Co), which was used to sensitize NiO films and evaluate the H2-evolving photoelectrochemical activity. The modest performances of the system could be explained through photolysis and post-operando characterizations, providing some guidelines for designing more efficient porphyrin-based assemblies.