Abstract
The development of non-noble metal electrocatalysts for energy conversion and storage devices such as fuel cells and electrolyzers has gained renewed interest in the last decades. Specifically, transition metal oxides are one of the material categories that showed remarkable efficiency and stability for hydrogen electrode reactions. This chapter summarizes the recent advances in the design and development of transition metal oxides for hydrogen evolution and oxidation reactions in different electrolytes. Special attention was given to the origin of the electrocatalytic performance and stability while relying on the elaboration-structure-efficiency correlation. Additionally, the mechanism of hydrogen electrode reactions in alkaline and acid media is discussed.