Hydrogen‐Associated Multiple Electronic Phase Transitions for d‐Orbital Transitional Metal Oxides: Progress, Application, and Beyond

Abstract Hydrogen‐associated electron doping Mottronics within d‐orbital transitional metal oxides (TMOs) opens up a new paradigm to explore exotic physical phenomena that enable promising applications such as artificial intelligence, Mottronic/iontronic devices, energy conversions, bio‐electronic sensing, and smart windows. Although remarkable progress is achieved over the past decade, systematic and in‐depth insights into hydrogen‐associated exotic physical phenomena within TMOs are still lacking. Herein, this review delivers a comprehensive and timely picture of hydrogen‐triggered electronic phase transitions within TMOs, covering the hydrogenation strategies, research progress, underneath mechanisms, multidisciplinary applications, and beyond. Furthermore, of particular interest, the hydrogenation or protonation enables the possibility of exploring the novel electronic phase and exotic physical properties within TMOs via breaking the intrinsic coupling in the charge, spin, lattice, and orbital degrees of freedom. Beyond that, a broader vision is further cast into the cutting‐edge researching fields of the multifunctionality associated with hydrogenated TMOs and the role of hydrogen in filling‐controlled Mottronic transitions by using hydrogenation. As combined with the critical overview of the existing open questions and future prospects, this review is expected to provide useful guidance on the hydrogen‐associated electronic phase transitions within TMOs and further broaden the promising applications.