Microwaves in clean energy technologies

Energy in the microwave spectrum is increasingly applied in clean energy technologies. This review discusses recent innovations using microwave fields in hydrogen production and synthesis of new battery materials, highlighting the unique properties of microwave heating. Key innovations include microwave-assisted hydrogen generation from water, hydrocarbons and ammonia and the synthesis of high-performance anode and cathode materials. Microwave-assisted catalytic water splitting using Gd-doped ceria achieves efficient hydrogen production below 250°C. For hydrocarbons, advanced microwave-active catalysts Fe-Ni alloys and ruthenium nanoparticles enable high conversion rates and hydrogen yields. In ammonia synthesis, microwaves reduce the energy demands of the Haber-Bosch process and enhance hydrogen production efficiency using catalysts such as ruthenium and Co₂Mo₃N. In battery technology, microwave-assisted synthesis of cathode materials like LiFePO₄ and LiNi_0.5Mn_1.5O₄ yields high-purity materials with superior electrochemical performance. Developing nanostructured and composite materials, including graphene-based anodes, significantly improves battery capacities and cycling stability. The ability of microwave technology to provide rapid, selective heating and enhance reaction rates offers significant advancements in clean energy technologies. Ongoing research continues to bridge theoretical understanding and practical applications, driving further innovations in this field. This review aims to highlight recent advances in clean energy technologies based upon the novel use of microwave energy. The potential impact of these emerging applications is now being fully understood in areas that are critical to achieving net zero and can contribute to the decarbonization of key sectors. Notable in this landscape are the sectors of hydrogen fuel and battery technologies. This review examines the role of microwaves in these areas.This article is part of the discussion meeting issue 'Microwave science in sustainability'.