Mo-doped Ni2P hollow nanostructures: highly efficient and durable bifunctional electrocatalysts for alkaline water splitting
Autor: | Wenyan She, Hongyang Zhao, Huan Jiao, Qin Wang, Fumin Li, Ling Xu, Xiaoming Wang |
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Rok vydání: | 2019 |
Předmět: |
Tafel equation
Materials science Renewable Energy Sustainability and the Environment Oxygen evolution 02 engineering and technology General Chemistry Glassy carbon 021001 nanoscience & nanotechnology Electrocatalyst Catalysis Active center chemistry.chemical_compound chemistry Chemical engineering Water splitting General Materials Science 0210 nano-technology Bifunctional |
Zdroj: | Journal of Materials Chemistry A. 7:7636-7643 |
ISSN: | 2050-7496 2050-7488 |
DOI: | 10.1039/c9ta01015g |
Popis: | The fabrication of an efficient bifunctional electrocatalyst towards alkaline overall water splitting is challenging, but in high demand. Herein, we report the construction of Mo-doped Ni2P hollow nanostructures through a solvothermal method and in situ phosphorization strategy. The Mo-doped Ni2P hollow nanostructures demonstrate excellent hydrogen evolution reaction (HER) activity in 1.0 M KOH solution with a low cathodic overpotential of 81 mV (10 mA cm−2, glassy carbon) and a small Tafel slope of 53.4 mV dec−1. First-principles density functional theory calculations reveal the mechanism of the alkaline HER. For pristine Ni2P, the P site serves as the active center. After Mo doping, the active center transforms to a bridging Mo–Ni site and the corresponding Gibbs free energy of H* absorption (ΔGH*) decreases from 0.33 eV (P site) to 0.21 eV (bridging Mo–Ni site). The optimal active site with a smaller ΔGH* can accelerate the charge transfer process for H* intermedium and H2 production. For the oxygen evolution reaction (OER), the Mo-doped Ni2P hollow nanostructures require 270 mV to attain 20 mA cm−2 (glassy carbon), with a small Tafel slope of 68.5 mV dec−1. Impressively, both the HER and OER catalysis exhibit durable performance in alkaline electrolyte. When the Mo-doped Ni2P hollow nanostructures are applied as bifunctional electrocatalysts for alkaline overall water splitting, the demanded cell voltage is only 1.54 V (10 mA cm−2, nickel foam). |
Databáze: | OpenAIRE |
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