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A rational design of electrocatalyst for oxygen reduction reaction (ORR) with activity 2–3 times higher than platinum has been of great demand for low temperature fuel cell applications. Particularly, metal-free ORR electrocatalysis has recently been explored rigorously because of limitations such as high price and scarcity of the state-of-the-art platinum catalyst. Here, we present a simple one-step method for the synthesis of carbon-doped hexagonal boron nitride (BNC) by a chemical vapor deposition method. An inert and insulating h-BN has been made active by carbon doping. From the structural analysis using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), we confirmed the formation of novel BNC nanostructures. BNC nanostructures exhibit rice grain-like shape having length ∼ 50 nm with interlayer distance of 0.34 nm, indicating hexagonal stacking of BN layers. As-synthesized BNC nanostructures obtained after annealing at 850 °C (BNC2-850) show interesting catalytic activity toward ORR with onset potential of 0.83 V versus RHE and a current density of 4.6 mA/cm2 in alkaline condition. More interestingly, the BNC2-850 nanostructures also reveal better stability even up to 10,000 potential cycles with concomitant negligible poisoning effect during methanol crossover process. Such a systematic and controlled study of carbon doping in h-BN nanostructures could certainly support the promising candidature of BNC as a metal-free electrocatalyst toward ORR.

Cobalt oxide with B,N,S tri-doped reduced graphite oxide exhibits synergistic effects to enhance ORR activity.

Owing to the unique and significant properties of the layered twodimensional (2D) structure of MXenes, they are being widely employed for various electrochemical device applications such as Li-ion batteries (LIBs), supercapacitors (SC), and hydrogen storage. Less attention has been paid toward their catalytic applications (energy conversion), perhaps due to the non-ideal electrochemical performance. Therefore, in the present study, we are reporting the preparation and electrocatalytic ability of MXene (Ti 3 C 2 T x ) and metal organic framework (Cobalt-MOF)-derived composites (Co-NC/Ti 3 C 2 -T). Interestingly, the optimized composite Co-NC/Ti 3 C 2 -800 reveals improved electrocatalytic oxygen reduction reaction (ORR) activity with a reasonably higher onset potential (E onset ) of 1.04 V versus reversible hydrogen electrode (RHE), a current density (J L ) of 4.8 mA/cm 2 , and a half wave potential (E 1/2 ) of 0.93 V versus RHE. Furthermore, the first order kinetics mechanism of ORR and percentage peroxide yield (HO 2 − ) were investigated using RRDE measurement. Finally, an optimized catalyst Co-NC/Ti 3 C 2 -800 demonstrates robust potential cycling performance (after 10k) over Pt/C under similar experimental conditions. Superior electrochemical performance of as-prepared nanocomposite materials is attributed to the redox centers of Co and the direct growth of a N-doped carbon network around a skeleton of Ti 3 C 2 T x that act as efficient charge transfer channel after redox reactions. Moreover, the formation of TiO 2 on the surface of MXene flakes may decrease the mass transport limitation and help to boost the electrocatalytic activity. Thus, the hybrid of MXene and Co-MOF (Co-NC/ Ti 3 C 2 -800) could be hopefully be a substitute for state-of-the-art catalysts, especially under alkaline conditions.

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