Production of hydrogen from alcohols via homogeneous catalytic transformations mediated by molecular transition-metal complexes

Hydrogen obtained from renewable sources such as water and alcohols is regarded as an efficient clean-burning alternative to non-renewable fuels. The use of the so-called bio-H regardless of its colour will be a significant step towards achieving global net-zero carbon goals. Challenges still persist however with conventional H storage, which include low-storage density and high cost of transportation apart from safety concerns. Global efforts have thus focussed on liquid organic hydrogen carriers (LOHCs), which have shown excellent potential for H storage while allowing safer large-scale transformation and easy on-site H generation. While water could be considered as the most convenient liquid inorganic hydrogen carrier (LIHC) on a long-term basis, the utilization of alcohols as LOHCs to generate on-demand H has tasted instant success. This has helped to draw a road-map of futuristic H storage and transportation. The current review brings to the fore the state-of-the-art developments in hydrogen generation from readily available, feed-agnostic bio-alcohols as LOHCs using molecular transition-metal catalysts.