Materials for green hydrogen production, storage, and conversion

H ydrogen: trickster, chameleon, the first element on the periodic table and the very fuel of the stars.As the most abundant element in the universe, hydrogen offers the tantalizing promise of virtually limitless, clean, carbon-free energy.Yet, on Earth, it has been thought to be vanishingly scarce in its molecular form, although recent discoveries of geologic hydrogen 1 could disrupt this assumption.Thus, although hydrogen-powered energy remains frustratingly out of reach at present, this situation could rapidly change.Beyond its potential role in energy, hydrogen makes its presence felt as a common and important atomic-scale defect in many solid-state materials systems, significantly influencing their properties and behavior.Often a villain in semiconductors or steels, interstitial hydrogen can also play the hero in certain catalysts or superconductors.Ubiquitous but still mysterious, hydrogen is the only element that can be explicitly described by the mathematics of quantum mechanics