Chapter 5: Theoretical Approach to Homogeneous Catalytic Reduction of CO₂: Mechanistic Understanding to Build New Catalysts

Conversion of CO₂ into liquid fuels and value-added fine chemicals has gained much attention in recent years to meet the ever-rising global energy demand and hence develop a sustainable solar fuel economy. This chapter enumerates feasible catalytic routes through which CO₂ could be utilized as a C1 feedstock. First, we address CO₂ functionalization catalysed by metal-free reagents and electrochemical CO₂ reduction mediated by organocatalysts and heterogeneous metal surfaces. Next, the reaction pathways undertaken by homogeneous molecular catalysts are highlighted; in particular, non-noble earth-abundant 3d transition metal-based complexes. At the end, we discuss our recent three case studies on two-electron reduction of CO₂, namely, CO₂ reductive disproportionation to CO and CO₃²⁻, and CO₂ hydrogenation to HCOO⁻/HCOOH. Here, we emphasize how mechanistic insights obtained by computational investigations could provide important guidelines to design tailored CO₂ reduction catalysts with higher efficiency and enhanced product selectivity.