Metal Oxide-Based Electrocatalytic Materials for Overall Water Splitting

Growing environmental problems and population growth have made it harder to find a sustainable alternative energy source to fossil fuels. The only accessible source of hydrogen that isn't derived from fossil fuels is water. Despite being one of the most widely used methods, electrochemical water splitting only generates 4% of the hydrogen used worldwide. The costly and insufficiently effective catalysts facilitating the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are among the causes. Among various efficient electrocatalysts for water splitting, metal oxides are typically promising candidates due to their extraordinary alloying effect towards OER and HER. Here, the historical development of electrocatalytic materials for overall water splitting is overviewed based on single, binary, ternary, mixed, high entropy, doped, and heterostructure metal oxides in terms of development for some possible avenues, structural arrangement, chemical composition, morphology, electrocatalytic activity, and robust long-term durability. Finally, concludes with perspectives relating to the challenges and opportunities of metal oxide-based electrocatalytic materials for overall water splitting.