Nitrogen-doped carbon coated nanodiamonds for electrocatalytic applications

Abstract

Nitrogen-doped carbon hybridized nanodiamond (N-doped C@ND) materials have been developed and used as an electrocatalytic for oxygen reduction reactions (ORRs). The polymerized ionic liquids are employed to modify NDs and then subjected to thermal annealing at 600 °C, resulting in a high concentration of N-doped (9.33 at.%) carbon frameworks attached on the ND surface. This N-doped C@ND material provides a highly active mesoporous structure (4 nm pore) with a high surface area (366 m² g⁻¹) and allows for enhancement of catalytic performance compared to pure NDs. The N-doped C layers altered the electroneutrality of NDs, creating favourable charged sites for oxygen adsorption, thus weakening the O–O bond strength to facilitate ORR activity. Having a predominant four-electron transfer pathway with a total electron transfer number of 3.44–3.88 in the potential region of 0.1–0.8 V(RHF), the N-doped C@ND-based catalyst materials performed well as a catalyst for the ORR in the alkaline medium. This affordable material and simple process will find potential application in clean energy generation and storage, durable fuel cells and metal–air batteries.