Electrode materials for electrochemical synthesis of carbon nanotube from CO2: Surface properties, mechanisms, and perspectives

Abstract

Carbon nanotubes (CNTs) are nanomaterials with exceptional electrical, thermal, and mechanical properties, making them highly attractive for advanced technological applications. While conventional synthesis methods, such as chemical vapor deposition (CVD) are well-established for large-scale CNT production, molten salt electrolysis has emerged as an alternative pathway that simultaneously enables CO₂ utilization and potential energy saving. This review highlights recent developments in the electrochemical synthesis of CNTs via molten salt systems, with particular emphasis on the surface properties and roles of electrode materials. Various electrode materials, including metals, alloys, metal oxides, graphite, and liquid metals, are critically analyzed based on their catalytic activity, carbon–metal interactions, and influence on carbon morphology. In addition, the criteria for stable anode materials under oxygen evolution conditions are discussed. The review also addresses major challenges, including CNT purity and structural control, scaling up the process for industrial applications, and enhancing energy efficiency. By consolidating recent progress and identifying key knowledge gaps, this work aims to guide future innovation in the rational design of electrode materials for sustainable CNT production via electrochemical CO₂ conversion.