Utilizing high entropy oxide (Ni0.2Co0.2Ca0.2Cu0.2Mg0.2)Fe2O4 in chemical looping process for highly efficient and stable hydrogen production

Chemical looping reforming coupled with water splitting (CLR-WS) offers a way for negative carbon H2 production when using bio-waste as raw materials. Iron-based oxides are highly anticipated as oxygen carriers (OCs), while the commercial application is hampered by the harsh conditions and low stability. High entropy materials (HEMs), including high entropy oxides (HEOs) and high entropy alloys (HEAs), have displayed multiple active catalytic sites with excellent stability in the field of electrochemistry and photochemistry. However, the family has rarely been studied in CLR-WS before. Herein, (Ni0.2Co0.2Ca0.2Cu0.2Mg0.2)Fe2O4 was synthesized and the H2 yield of 12.66 mmol/g OC with the purity of 99.1 % was exhibited at 700 °C, proved to be at the forefront of the existing literatures. This study first creates a sustainable loop between HEO and HEA and achieves highly efficient and stable H2 production, paving an avenue for the large-scale application of HEM in thermochemical process.