Hydrogen Energy as Sustainable Energy Resource for Carbon-Neutrality Realization

For stepping toward a sustainable future, reducing carbon footprints by generation of a clean source of energy is a viable option that captivates researchers all around the globe. Hydrogen energy in the form of renewable energy resource has achieved sustainable status and is perceived as a feasible alternative of fossil derivative fuels ascribed to higher gravimetric density, which offers superior efficiency over conventional fuels. However, the nature of the H2 synthetic route is a determinant for clean energy production. Traditional gray H2 production generated via fossil fuels catalyzes global warming. Therefore, there is the need to develop environmentally benign methodologies such as green and blue H2 generation routes which are discussed in this review article by comparing distinct methods for the production of H2 with minimal carbon emission, along with their merits and demerits. We have precisely discussed the optimization of photocatalytic H2 evolution by optimizing the cost and catalytic system in terms of sustainability. Exploitation of cheap and noble metal free catalysts has been stressed for generating green H2. The research domain of this article underlines the significance of green H2 production in attaining a carbon-neutral society with respect to H2 economy and its techno-economic analysis toward scalable applicability.