Efficient preparation of carbon materials composed of warped graphene layers via in-situ nano-templating and estimation of oxygen reduction reaction activity

Abstract

The warped graphene layer (WGL) has garnered attention as a potential alternative to Pt for oxygen reduction reaction (ORR) catalysts and as a platform for enhancing the activity of Pt or molecular catalysts through interactions. We propose an in-situ nano-templating method for the preparation and mass production of WGLs and demonstrate its efficiency. The in-situ nano-templating method facilitates the synthesis of materials with three-dimensional curvature by concurrently generating nanoparticles and carbonizing. The synthesized WGLs exhibited high ORR activity in acidic conditions. Although the ORR activity was not correlated with the surface area, it was strongly correlated with the curvature radius of the WGLs. This activity was considered to arise owing to the optimization of oxygen adsorption ΔG0 with the decrease in the curvature radius of the WGLs; furthermore, the physicochemical characteristics of WGL possesses continuity of carbon layers and exhibit a Fermi level higher than the O2/H2O reduction potential. This report elucidates experimentally that WGLs contribute to ORR activity, suggesting the importance of incorporating WGLs in the development of non-precious metal catalysts.