Metal oxyhydroxides represent a promising path towards a sustainable energy future but research needs to optimize synthesis and explore new nanostructures to fully realize their potential聽
The transition from fossil fuels to renewable energy is a pressing challenge, with climate change, environmental degradation, and resource depletion driving the search for sustainable alternatives. Electrochemical energy conversion and storage (EECS) technologies hold significant promise and central to these are advanced materials that enhance their efficiency and performance. One such group of materials, metal oxyhydroxides (MOOHs), is poised to play a crucial role in the future of energy.
In this review article, a team of researchers including Khalifa University鈥檚 Dr. Karuppasamy Karuppasamy, under the guidance of Prof. Akram AlFantazi, reported on the advancements in MOOHs, focusing on their synthesis, structural engineering and applications in EECS. Dr. Karuppasamy collaborated with researchers from Gyeongsang National University, South Korea; Vellore Institute of Technology, India; Federal University of Mato Grosso do Sul, Brazil; The Oxford College of Science, India; Chulalongkorn University, Thailand; and Dongguk University-Seoul, Republic of Korea.
Their results were published in, a top 1% journal.
Metal oxyhydroxides are a type of transitional metal compound that includes elements like manganese, nickel, iron, and cobalt. These materials have unique electronic structures and variable valence states, which make them particularly effective as electrocatalysts and electrode materials. Their 2D layered structures, comprising edge-sharing octahedral subunits, allow for high conductivity and improved surface texture. Various ions are also inserted into the structure to enhance the material鈥檚 overall electrochemical performance.
MOOHs are especially promising in supercapacitor applications. Supercapacitors are energy storage devices with high power density, long cycle life, and fast charge-discharge capabilities.
鈥淢OOHs such as cobalt oxyhydroxide and nickel oxyhydroxide have shown remarkable performance as supercapacitor electrodes,鈥� Dr. Karuppasamy says. 鈥淔or instance, cobalt oxyhydroxide exhibits a high specific capacitance and stability due to its mixed valence states, which facilitate excellent reversible redox reactions.鈥�
In battery technology, transition metal oxyhydroxides can serve as electrode materials in alkali metal ion batteries, providing high energy density and cycling stability. Their ability to undergo reversible redox reactions makes them ideal for next-generation battery applications, with the potential to surpass traditional materials in performance.
MOOHs are also effective catalysts for water electrolysis, a process which produces hydrogen fuel by splitting water into hydrogen and oxygen and is vital for the development of clean hydrogen energy. The MOOH structural properties allow for efficient electron transfer and ion diffusion, making them highly effective for both the hydrogen evolution reaction and the oxygen evolution reaction.
Synthesizing MOOHs involves various innovative methods, each with their own advantages. Hydrothermal and solvothermal processes allow for precise control over the nanostructures and chemical compositions, producing high-purity materials with desirable properties, while the sol-gel process produces multicomponent systems at low temperatures. Microwave-assisted synthesis is rapid and energy efficient but requires specialized equipment.
Despite their potential, MOOHs face several challenges. Scaling up production while maintaining quality and performance is a significant hurdle. Additionally, ensuring the long-term stability of MOOH-based materials in various electrochemical environments remains a concern.
MOOHs could revolutionize the field of EECS but continued research and development will be essential to fully realize their potential.
Jade Sterling
Science Writer
3 July 2024
