Energy Decarbonization via Green H₂ or NH₃?

Due to the global need to decarbonize, it is increasingly clear that we are heading toward a new era of massive renewable energy generation and utilization to substitute fossil fuels. However, pragmatic means for renewable energy storage, transportation, and utilization at a very large scale are not yet fully developed and require careful scrutiny. In this Focus Review, we will consider the thermodynamics, kinetic barriers, material challenges, current science and technology readiness, and geographical locations for green hydrogen versus green ammonia as energy vectors for suitable sustainability of our future economy.