Bimetallic Ni2-xCoxP/N-doped carbon nanofibers: Solid-solution-alloy engineering toward efficient hydrogen evolution

• Published in: Applied catalysis. B, Environmental Environmental, 2019-05, Vol.244, p.620-627
• Main Authors: Mo, Qijie, Zhang, Wenbiao, He, Liuqing, Yu, Xiang, Gao, Qingsheng
• Format: Article
• Language: English
• Subjects: Alloys; Bimetals; Carbon; Carbon fibers; Catalysis; Chemical evolution; Electrocatalysts; Electronic modulation; Engineering; Evolution; Hydrogen; Hydrogen binding energy; Hydrogen evolution reaction; Hydrogen evolution reactions; Hydrogen-based energy; Metal phosphides; Metals; Nanofibers; Noble metals; Optimization; Pyrolysis; Solid solutions; Solid-Solution alloy; Sulfuric acid; Ultrafines; Water splitting
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2018.11.083

[Display omitted] •Electrospinning is introduced to design Ni2-xCoxP/N-C NFs with tailored electronic configuration.•Electronic modulation leads to the enhanced hydrogen binding and the promoted HER kinetics.•Optimal Ni2-xCoxP/N-C NFs deliver high efficiency for HER and overall water splitting. Exploring noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) is the key issue in hydrogen economy blueprint. Herein, bimetallic Ni2-xCoxP supported by N-doped carbon nanofibers (denoted as Ni2-xCoxP/N-C NFs) are developed via electrospinning followed by pyrolysis under an inert flow. The space confinement by in-situ formed N-doped carbon matrix produces ultrafine Ni2-xCoxP with abundant active-sites. More importantly, the engineering on Ni2-xCoxP solid-solution-alloys can vary electronic configuration and consequently optimize hydrogen binding on electrocatalyst surface, accomplishing prominent HER activity in a wide pH range. The optimal Ni2-xCoxP/N-C NFs afford low overpotentials (η10) of 100, 130 and 110 mV to reach a current density of -10 mA cm−2 in 0.5 M H2SO4, 1.0 KOH and 1.0 M PBS (phosphate buffer saline), respectively, performing among the best of noble-metal-free electrocatalysts. With a good functionality for oxygen evolution (η10 = 280 mV), such composite further delivers a high efficiency for overall water splitting, featuring a comparable cell voltage (1.56 V @ 10 mA cm−2) to a commercial IrO2/C − Pt/C couple, and remarkably better stability. Identifying electrocatalysis relying on solid-solution alloys, this work will inspire the exploration of cost-efficient electrocatalysts and the new understanding on catalytic mechanisms.