Biological carbon dioxide reduction is a critical reaction for sustaining life on earth. CO₂ is the primary chemical building block for most complex and higher energy carbon compounds required for metabolism and growth, and nature has developed incredibly elegant mechanisms for its reduction and up-conversion into such materials.¹  Enzymes broadly termed carbon dioxide reductases (CO₂Red) efficiently catalyse the reduction of CO₂ into a variety of lower oxidation state carbon products at rates that enable the functioning of complex organisms.²  Autotrophs utilise CO₂ as a substrate, powered by solar radiation in the case of phototrophs (Figure 2.1), or from reducing chemicals in the case of chemotrophs; such organisms are the fundamental chemical energy source for all non-autotrophic life-forms.³