Low-valent molecular cobalt complexes for CO2 reduction

This chapter explores the most representative catalytic systems for electro- and photocatalytic CO2 reduction into fuels and chemicals, as promising strategies to produce carbon-based fuels and chemicals in a sustainable manner. Practical application of CO2 reduction faces challenges such as enhancing catalyst activity (turnover numbers, turnover frequencies), achieving high energy efficiency (low overpotential), ensuring excellent selectivity and efficiency for desired products (Faraday efficiencies, product yield, quantum yields), and maintaining long-term stability used earth-abundant-based systems. A deeper understanding of reaction mechanisms is crucial to favor pathways yielding desired products while avoiding undesired ones. Recent years have seen the emergence of rational design strategies to boost activity without compromising overpotential or selectivity. This review focuses on molecular cobalt-based catalysts as pivotal components in this evolution. The chapter is divided into two main sections: the first covers the developed and studied cobalt complexes based on heme ligands, such as porphyrins and phthalocyanines, while the second addresses cobalt complexes with non-heme ligands. Key aspects for catalyst development in this rapidly advancing field are discussed.