Electrospinning Preparation of N, P Dual-Doped Molybdenum Carbide/Porous Carbon Fibers with Highly Improved Electrocatalytic Activity for Hydrogen Evolution Reaction

Abstract

In this work, N, P dual-doped molybdenum carbide/porous carbon fiber composites were simply fabricated through electrospinning technology, followed by pyrolysis. The obtained samples were composed of N, P-doped MoC, Mo2C, and porous carbon fibers. Compared with each moiety, the composited samples have exhibited greatly improved electrocatalytic activities for hydrogen evolution reaction (HER). As a result, the optimized MoxC-NPC-1.0-800 catalyst exhibits only 125/71 mV of overpotential at 10 mA·cm–2 and superior stability in 0.5 M H2SO4 and 1.0 M KOH, respectively, which outperforms most of the reported analogous catalysts. In addition, a theoretical simulation has confirmed that N, P doping can significantly reduce |ΔG H *| for hydrogen adsorption of MoC and Mo2C and consequently enhance the electrocatalytic activity of the catalysts for HER greatly. This work provides a convenient avenue for fabricating highly efficient composite electrocatalysts of nonmetallic element doped metallic carbide and graphitic carbon.

Mn boosted the electrocatalytic hydrogen evolution of N, P co-doped Mo2C via synergistically tuning the electronic structures

“…3e, the XPS spectrum of N 1s for 0.08MnNP-Mo 2 C validates the presence of graphitic N (400.76 eV), pyrrolic N (399.58 eV), pyridinic N (398.14 eV) and Mo 3p (394.91 eV), confirming the doping of heteroatom N into the carbon matrix. 55 Furthermore, the characteristic peak (396.18 eV) belonging to N–Mo/N–Mn bonds shows that N and Mn dopants are successfully introduced into Mo 2 C. 52,70 Likewise, NP-Mo 2 C exhibits similar peaks of graphitic N (401.15 eV), pyrrolic N (399.55 eV), pyridinic N (398.01 eV), Mo 3p (395.22 eV) and the N–Mo bond (396.45 eV). 55 In the C 1s spectrum of 0.08MnNP-Mo 2 C (Fig.…”

“…51 Besides, the surface wettability of Mo 2 C was enhanced aer the addition of polar N-Mo, P-Mo and S-Mo bonds by N, S and P doping. [51][52][53] Noticeably, Mn possesses a lower electronegativity (Mn: 1.55, Fe: 1.83, Co: 1.88, Ni: 1.91, Ag: 1.93 and Mo: 2.16) and sufficient d-orbital electrons, which has demonstrated a positive role in ne-tuned electronic structures of Mn, N co-doped Mo 2 C and Mn, and P co-doped Mo 2 C, thus boosting HER performances. 54,55 Consequently, the expected electron interaction could emerge and more active sites related with N, P will be formed aer Mn is introduced into N, P dual-doped Mo 2 C. However, to the best of our knowledge, the inuence of Mn addition on HER performances of NP-Mo 2 C has seldom been reported.…”

Synergistically coupling P-doped Mo2C@N, P dual-doped carbon-nanoribbons as an efficient electrocatalyst for the hydrogen evolution reaction

“…[19][20][21] Furthermore, N, P dual-doped Mo 2 C/porous carbon fiber composites exhibited good HER performance in 0.5 M H 2 SO 4 and 1.0 M KOH. 5 Besides, Chi et al 19 prepared a catalyst with Mo 2 C and MoP encapsulated into N, P co-doped carbon shells, which exhibited good HER performance in basic and neutral media with Z 10 (the overpotential to afford the current density of 10 mA cm À2 ) values of only 169 mV and 228 mV, respectively. Therefore, the combination of both conductive carriers and P-doping will probably result in excellent HER performance.…”

“…4 In the past few decades, researchers have been exploring non-noble metal catalysts with comparable HER catalytic activity and stability to platinum (Pt) based catalysts, so as to reduce the cost and bring about industrialization. Transition-metal compounds such as carbides, 5,6 sulfides, 7,8 phosphides, 9,10 and nitrides 11 have been extensively employed as the electrode materials in the HER due to their Pt-like electronic structures and catalytic activities.…”

“…On the other hand, except for the conductivity limitation, the strong H-bonds resulting from the empty d-orbital band of Mo 2 C limit its intrinsic HER activity. 5 Researchers have made arduous efforts to dope the Mo 2 C crystal lattice with non-metallic elements (such as N, S, and P) that possess lower electronegativity to increase the active sites. In particular, P-doping reduces the density of the empty d-bands in Mo 2 C and therefore attenuates the strength of the Mo–H bond.…”