Transforming Two-Dimensional Boron Carbide into Boron and Chlorine Dual-Doped Carbon Nanotubes by Chlorination for Efficient Oxygen Reduction

Our theoretical calculations suggest that the synergistic effect between the electron acceptor (B) and donor (Cl) in carbon nanotubes (CNTs) (BClCNTs) is the key to excellent oxygen reduction reaction (ORR) activity. However, the rational fabrication of BClCNTs is still an open question. Here, we first present a metal free and controlled strategy for successful preparation of BClCNTs via chemically tailoring two-dimensional (2D) boron carbide (B4C) with Cl-2. Accompanied by partial extraction of B atoms from B4C with Cl-2, the residue B and C atoms combining with Cl atoms self-organize into nanotube microstructures. Significantly, the amount of heteroatoms (B and Cl) can be tuned in terms of altering chlorine-to-carbide molar ratios. As expected, as a metal-free ORR catalyst, the produced BClCNTs exhibit a higher onset potential (0.94 V vs a reversible hydrogen electrode; RHE) and half-wave potential (0.84 V) as well as greater stability than those of commercial Pt/C (0.92 and 0.80 V).