Large-scale and controllable synthesis of metal-free nitrogen-doped carbon nanofibers and nanocoils over water-soluble Na₂CO₃

Using acetylene as carbon source, ammonia as nitrogen source, and Na₂CO₃ powder as catalyst, we synthesized nitrogen-doped carbon nanofibers (N-CNFs) and carbon nanocoils (N-CNCs) selectively at 450 °C and 500 °C, respectively. The water-soluble Na₂CO₃ is removed through simple washing with water and the nitrogen-doped carbon nanomaterials can be collected in high purity. The approach is simple, inexpensive, and environment benign; it can be used for controlled production of N-CNFs or N-CNCs. We report the role of catalyst, the effect of pyrolysis temperature, and the photoluminescence properties of the asharvested N-CNFs and N-CNCs.