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A novel Fe-doped urchin-like Ni 2 P/Ni 3 S 2 (NPZFNS@C/NF) heterostructure with abundant hetero-interfaces and carbon-coating is successfully constructed, which exhibits outstanding oxygen evolution reaction (OER) performance and excellent hydrogen evolution reaction (HER) performance. Furthermore, it also exhibits a small overpotential of 1.5 V for overall water splitting with NPZFNS/NF as both anode and cathode, lower than most of non-noble metal-based bifunctional electrocatalysts reported. [Display omitted] • Fe-doped Fe-Ni 3 S 2 /Ni 2 P@C/NF hetero-interface electrocatalyst is firstly constructed. • The catalyst shows oustanding OER and excellent HER performances. • It can act as a bifunctional catalyst toward excellent overall water splitting bebavior. • The unique electronic structure of the catalyst is the intrinsic reason for the excellent OER and HER performances. • DFT calculations further reveal the changes the d-band center and the rate-degerming step. Interfacial engineering is an efficient strategy to develop electrocatalysts with excellent performance. By using this strategy, a novel Fe-doped urchin-like Ni 2 P/Ni 3 S 2 (NPZFNS@C/NF) heterostructure with metal–organic frameworks (MOFs) as the precursor in-suit grows on nickel foam (NF) with abundant hetero-interfaces and carbon-coating is successfully constructed. Owing to the existence of hetero-interfaces and carbon coating, the unique surface electronic structure and d-band center of NPZFNS@C/NF are also obtained. Benefiting from the regulation of electronic structure and d-band center, the NPZFNS@C/NF electrode exhibits extremely high activity for oxygen evolution reaction (OER) and high activity for hydrogen evolution reaction (HER), which shows a very low overpotential of 141 mV at the current density of 10 mA cm−2 for OER and 129 mV for HER respectively in alkaline electrolyte. Furthermore, it also exhibits a small overpotential of 1.5 V for overall water splitting with NPZFNS@C/NF as both anode and cathode, which is lower than most of non-noble metal-based bifunctional electrocatalysts reported. Density functional theory (DFT) results further confirm that the hetero-interface with carbon coating can further optimize Gibbs free energies for both OER and HER processes. This design and constructure strategy provides a new avenue for overall water splitting. [ABSTRACT FROM AUTHOR]

A series of FeNi 2 S 4 /NiS hetero-interface electrocatalysts with unique electronic structures are successfully constructed by interfacial engineering. Particularly, the optimized FeNi 2 S 4 (311)/NiS (101) electrocatalyst is obtained by modulating the different exposed crystal planes, which shows superior nitrogen reduction performance with high NH 3 yield and high Faradaic efficiency. • MOF-based sulfides FeNi 2 S 4 /NiS hetero-interface electrocatalysts are firstly constructed. • FeNi 2 S 4 (311)/NiS(101) shows superior electrocatalytic NRR performance. • The unique surface electronic structure of catalysts is the intrinsic reason for the excellent NRR performance. • DFT calculations further reveal the changes the d-band center and the rate-degerming step. Electrocatalytic Nitrogen Reduction Reaction (ECNRR) is a promising alternative NH 3 production method relative to Haber-Bosch process. However, the ECNRR still suffers from rather low NH 3 yield and selectivity (Faradaic efficiency (FE)) due to the poor catalytic activity of catalysts. Herein, benefiting from interface engineering, FeNi 2 S 4 /NiS hetero-interface electrocatalysts with unique electronic structures are successfully constructed, which the optimized catalyst can enhance the adsorption of N 2 molecules meanwhile inhibit H atoms adsorption. Significantly, the NH 3 yield and FE of FNS/CC-2 are reached to 128.398±1.32 μg h−1 cm−2 and 28.64 ± 0.18% which are higher than most of non-noble metal-based NRR electrocatalysts in alkaline electrolyte reported. Detailed experimental investigation and DFT calculations reveal that the enhanced electrocatalytic performance and selectivity of FeNi 2 S 4 /NiS towards N 2 are attributed to the changes of the D-band center and electronic structure of electrocatalyst surface. The construction strategy of this NRR electrocatalyst provides a new avenue on electrocatalytic research. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) in pH-neutral electrolyte is considered more difficult for the additional adsorption and the dissociation process of H 2 O. Herein, by in-suit construction of the heterostructure between MgO and NiCo 2 S 4 on carbon cloth (CC), a novel MgO/NiCo 2 S 4 heterostructure on CC (MgO/NCS-CC) is successfully fabricated. Benefitting from the optimized electronic structure attributed to the construction of hetero-interface, and the intense adsorption of H 2 O on the surface of catalysts owing to the introduction of hydration-effect-promoting (HEP) element Mg, the MgO/NCS-CC exhibits outstanding OER activity with overpotential of 145 mV at the current density of 10 mA·cm−2 in pH-neutral electrolyte and can maintain stability over 40 h. Density-functional theory (DFT) also demonstrates that the MgO/NiCo 2 S 4 heterostructure can effectively adjust the electronic structure and enhance the adsorption of reactant, thus further optimizing Gibbs free energies and improving the activity for OER in pH-neutral electrolyte. [Display omitted] • The hydration-enhancing-effect element Mg effectively enhanced the adsorption of H 2 O on the surface of catalyst. • The unique electronic structure of the heterostructure is the intrinsic reason for the super OER performance. • The catalyst shows outstanding OER performances and excellent stability in pH-neutral condition. • DFT calculation further reveals the change of electronic structure and the enhancement of water adsorption of the catalyst. [ABSTRACT FROM AUTHOR]