Rapid Chemical Synthesis of High-Entropy Oxide Colloids under Ambient Conditions

High-entropy oxides (HEOs) exhibit high catalytic activities in the O 2 evolution reaction (OER). Nevertheless, the methods used for the fabrication of these oxides necessitate the application of heat and/or pressure. Accordingly, herein, HEO colloids are produced by a facile procedure under ambient temperature and pressure conditions using a strong base, an oxidant, and metal salt(s). Using the proposed method, HEO colloids containing up to 12 metal elements are prepared and specifically tailored as electrocatalysts for the OER. This chemical approach enables the cost-effective production of HEO colloids with diverse compositions, opening the door to a wide range of applications of HEOs.