Activation of Energy-Relevant Small Molecules by Metallocorroles

Atif Mahammed, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, Israel
Abhishek Dey, Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata, India
Zeev Gross, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, Israel

Small molecules such as H₂O, CO₂, O₂, and N₂ are readily accessible and inexpensive, so that it is highly desirable to include them into syntheses of value-added products or to use them as reservoirs of chemical energy. However at the same time they are typically thermodynamically stable, so that their utilization requires an activation step. Electrolytic reduction of water as to produce hydrogen is one of the most convenient ways to store energy, which would be durable if the electrical energy is obtained from renewable and cheap resources. While electrolysis is a mature and robust technology, the most promising devices, rely on the use of platinum as an electrocatalyst to accelerate both hydrogen evolution and water oxidation.  However, this rare and expensive metal is not itself a sustainable resource, so the viability of a hydrogen economy depends on the design of new efficient and robust electrocatalytic materials based on abundant elements such as first row transition metals.

We have recently introduced cobalt corroles as catalysts for both reactions and shown how to tune their redox potentials and catalytic activity.¹ One major path is to affect the above by halogenation of the macrocycle. This approach led to significant advances regarding the two important aspects required for water splitting, the hydrogen and oxygen evolution reactions.

References

1. a) Mahammed A, Botoshansky M,  and Gross Z. Dalton Trans. 2012, 41, 10938. b) Mahammed A, Tumanskii B, and Gross Z. J. Porphyrins Phthalocyanines 2011, 15, 1275. c) Schechter A, Stanevsky M, Mahammed A, and Gross Z. Inorg. Chem. 2012, 51, 22. d) Mondal B, Sengupta K,  Rana A, Mahammed A, Botoshansky M, Dey SG, Gross Z, and Dey A. Inorg. Chem. 2013, 52, 3381. e) Mahammed A, Mondal B, Rana A, Dey A, and Gross Z. Chem. Commun. 2014, 50, 2725.