ABSTRACT
The need for energy has increased considerably around the world because of industrialization, population growth, and the use of fossil fuels running out. So, the need for a sustainable energy supply is one of the most important socioeconomic problems the world faces in the 21st century, and any renewable energy sources that could replace fossil fuels are now essential to solving this problem. Hydrogen is the best-known organic liquid system, and it has received a lot of attention because of the current “energy crisis” and 146concerns about the environment. However, since hydrogen has a very low energy density per volume (10 kJ/L), it is not appropriate for the storage or transportation of massive quantities of energy. This has forced researchers to identify a favorable hydrogen carrier for the “hydrogen economy,” which is not only capable of storing H2 physically or chemically in high concentration but also capable of discharging it readily on demand. Liquid organic hydrogen carriers (LOHCs) that employ a “green hydrogen production” approach (i.e., catalytic H2 production using an earth-abundant, nontoxic, as well as cost-effective metal-based catalyst) represent an emerging technology for a creative future energy source. Common LOHCs like ammonia and hydrazine are usually poisonous, flammable, and explosive, which restricts their practical application. Formic acid (FA), which has 4.4% by weight hydrogen, is currently gaining favor as an LOHC due to its stability, low toxicity, biodegradability, practical storage and transport, and propensity for on-demand H2 release. Fortunately, the only by-product of FA dehydrogenation is CO2, which is effortlessly recovered and catalytically reduced back to FA, making it feasible to frequently utilize H2 by concluding the dehydrogenation−hydrogenation cycle. However, the last process presents a thermodynamic issue. Metal-based homogeneous or heterogeneous catalysts are the best option for such reactions; yet, heterogeneous catalytic systems offer a convenient alternative over homogenous ones by providing ease in their recovery for being reused in reactions, as the latter has inherent recyclability issues, and the use of expensive ligands and additives hinders their industrial-scale application. The decisive design of metal nanostructures, however, which enables the development of high-performance materials with tailored properties to accomplish target reactions, offers the greatest difficulties for controlling the activity and specificity of heterogeneous catalysts. Recently, heteroatom-doped graphene and carbon systems in combination with transition metals have been demonstrated to be efficacious heterogeneous catalyst systems that govern a variety of uses, including reductions, oxidations, C−C bond formation, etc.
Herein, with a rational strategy toward the mitigation of the “energy crisis,” the novel methods and strategies for a hydrogen economy are summarized. The modernist perspective on the emergence of formic acid as a hydrogen generator will be emphasized in this chapter. Furthermore, its decomposition using heterogeneous and homogeneous catalysts received a good deal of attention. The chapter’s conclusion offers an in-depth summary of the necessary actions that must be taken in order to lay the groundwork for a hydrogen economy based on FA.
