Journal
APPLIED CATALYSIS B-ENVIRONMENTAL
Volume 263, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.apcatb.2019.118338
Keywords
Bifunctional electrocatalysts; (Fe-Ni)Co-x- OH/Ni3S2 nanohybrid; Interfacial effects; DFT calculations; Water splitting
Funding
- National Natural Science Foundation of China [51103120]
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Rational design of earth-abundant electrocatalysts with ultra-high activity and durability for the electrochemical water-to-energy conversion systems is still a significant challenge. Herein, a hierarchical nanocluster hybrids of trimetallic (Fe-Ni)Co-x - OH nanofilms decorated amorphous Ni3S2 with S-vacancy supported on nickel foam (NF) was proposed via rapid two-step electrodeposited pathway. By effectively breaking long-range-order of Ni3S2 to form S-vacant amorphous phase, combining with the strong electronic interactions between the (FeNi)Co-x - OH and Ni3S2, it resulted in favorable water adsorption ability, free-energy of H* adsorption (Delta G(H*)) and fast mass/charge transfer for hydrogen evolution process. The (Fe-Ni)Co-x - OH/Ni3S2 nanohybrids displayed ultralow overpotential of 91 and 145 mV at 100 and 1400 mA.cm(-2) respectively with admirable durability for 100 h at 200 mA.cm(-2) in 1 M KOH, even exceeding Pt plate. The amorphous S-vacant Ni3S2 plays a crucial role for hydrogen evolution: compared with both original and defective Ni3S2, the free energy of disordering Ni3S2 for *H - OH and H* intermediates more tend to thermodynamical neutrality according to density functional theory (DFT) calculations. For water-to-oxygen evolution (eta(100) = 280 mV), in situ newly formed ultrathin NiOOH nanosheets on near-surface Ni3S2 layer coupling with (Fe-Ni)Co-x - OH nanofilms can be identified as intrinsic OER active species; and the host metallic Ni3S2 phase provides wonderful conductivity. Impressively, the bifunctional (Fe-Ni)Co-x - OH/Ni3S2 nanohybrid represents the best electrocatalyst so far, achieving cell-voltage of 1.45 and 1.61 V at 10 and 200 mA.cm(-2) respectively with super stability for 100 h.
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