Three-dimensional graphene-based macrostructures for sustainable energy applications and climate change mitigation

The importance of three-dimensional (3D) graphene-based macrostructures (GBMs) is increasingly being recognized over the last five years for diverse clean energy-related applications and global climate change mitigation. With exceptionally large specific surface area and highly interconnected pore networks, 3D graphene scaffolds manifest extraordinary nanoscale effects that result in materials with unusual electrical, mechanical, and electrochemical properties. A global multidisciplinary research effort focusing on the development of innovative 3D GBMs with hierarchical microstructures and novel functionalities has therefore recently emerged. This review provides a comprehensive account of the key design principles in preparing high performance 3D GBMs and discusses their application as advanced electrode materials in a range of energy storage and conversion devices, including lithium-ion batteries, supercapacitors, fuel cells, dye-sensitized solar cells, and photoelectrochemical water splitting units. In addition, the review provides insights into newer and emerging sustainable energy applications of 3D GBMs, such as adsorbents for high-density hydrogen storage and selective capture of CO2 from flue gases, as well as catalysts for photoconversion of CO2 into clean fuels and value-added chemicals. The current state of knowledge is highlighted for each of the applications, followed by a discussion of our own perspectives on each topic. Finally, the future outlook on practical deployment of 3D GBMs is suggested as concluding remarks.