2, School of Physics and Electronic Engineering, Xuzhou, , China
Boron carbon nitride (BCN) is a novel ternary hybrid material between carbon and BN with tuneable compositions of B-C-N.1 So far, the nanostructures of BCN include zero-dimensional (0D) BCN nanoparticles, one-dimensional (1D) BCN nanoscrolls, two-dimensional BCN nanosheets and three dimensional (3D) BCN monolith.2-4 With the controllable band gaps (0-5.5 eV), BCN nanomaterials have shown many striking properties such as cathodoluminescence (CL) emission and photoredox catalytic activities.2 Besides, the hetetro-polarity of B,N bonding greatly stimulates the electrochemical activity, benefiting the versatility of BCN nanomaterials in energy conversion and storage applications such as oxygen reduction reaction (ORR) and lithium-ion batteries.4,5 As supercapacitor electrodes, carbon-based nanomaterials such as carbon nanotube and graphene are most widely reported. Since they exhibit the merits of light weight, high surface areas and good conductivity compared with transition metal oxides and conducting polymers. Nevertheless, most carbon materials only show electrical double-layer capacitance (EDLC), which restrict the capacity. To enhance the capacitance, recently heteroatoms such as B, N doping are preferred. By introducing B or N elements, it generates a pseudo-capacitance, endowing faster reversible redox reactions and thus resulting in improved capacity. Therefore, it is believed that BCN nanomaterials are promising for supercapacitor electrodes. For one thing, B, N co-doped in the carbon network could induce larger faradic pseudo-capacitance than single element doping. For another, when contacting the aqueous electrolytes, the hetero-polar B-N bonding is capable of providing an extra dipole, thus likely facilitating the relative wettability between electrode materials and electrolytes. As a result, more ions could access the pores as well as being attached on the surface of BCN than that of pure carbon nanomaterials.1 However, there still remain some challenges. As supercapacitor electrode, BCN nanomaterials generally maintain high capacitance at relatively low charge and discharge current. For the reason that, the faradic pseudo-capacitance induced by heteroatoms tends to be irreversible and deteriorative under fast charging/discharging. In addition, excessive B-N domains would reduce the conductivity. Hence, in the future study, it is necessary to elaborately design BCN nanomaterials with decent B, N doping and structure for better improving the electrode performance.
1.J. Wang, C. Chen, C. Yang, Y. Fan, D. Liu, W. Lei, Curr.Graph.Sci. 2017, 1, 1
2.W. Lei, D. Portehault, R. Dimova, M. Antonietti, J. Am. Chem. Soc.2011, 133, 7121.
3.J. Wang, J. Hao, D. Liu, S. Qin, C. Chen, C. Yang, Y. Liu, T. Yang, Y. Fan, Y. Chen, W. Lei
Nanoscale 2017, 9, 9787.
4. J. Wang, J. Hao, D. Liu, S. Qin, D. Portehault, Y. Lin, Y. Chen, W. Lei, ACS Energy Lett. 2017, 2, 306.
5. W. Lei, S. Qin, D. Liu, D. Portehault, Z. Liu, Y. Chen, Chem commun. 2013, 49, 352.