Material challenges in green hydrogen ecosystem

Green hydrogen (H2) is one of the most promising candidates to combat the global energy crisis because of its high energy density, sustainability and abundance on earth. Large-scale green H2 ecosystems that empower the global transition towards a carbon-neutral energy society are highly desired, yet challenging, to be deployed. Limitations such as relatively low production and storage efficiencies from renewable technologies, high transportation and utilization costs and safety concerns regarding H2 handling greatly restrain the development of green H2 ecosystems. Revolutions in materials science and technology are crucial to tackle these issues and construct practical green H2 ecosystems. Though reviews focus exclusively on the material development in individual sectors of the H2 ecosystem, they lack a review focusing on the material challenges and advances in the green H2 ecosystem in a comprehensive and instructive manner. It is pivotal to providing constructive and universal solutions for common material challenges in green H2 technologies, bringing together efforts from all relevant fields and exploring new opportunities and breakthroughs. Herein, this review features cutting-edge material advances and identifies the critical material challenges throughout the entire green H2 ecosystem, including renewable H2 production, purification, storage, transportation, application and safety and cost management. Promising strategies proposed in material progress in the past five years are analyzed to address the material challenges and provide practical and goal-oriented approaches to the material revolution in green H2related technologies. In-depth insights into cost management are also covered in this review to inspire the translation of advances in materials science into practical large-scale green H2 ecosystems. This is the very first comprehensive and goal-oriented review that presents an overall picture of the entire green H2 ecosystem, as well as the role and specific material requirements and advancement in each part of the ecosystem. In this way, this review will identify the current bottlenecks or fundamental challenges that require urgent breakthroughs in the entire green H2 ecosystem instead of focusing on a particular part so that more effort can be directed to those directions to achieve fast advancement. It will pave the way for building up a green and sustainable H2 economy in the near future.