One‐Step In Situ Growth of Iron–Nickel Sulfide Nanosheets on FeNi Alloy Foils: High‐Performance and Self‐Supported Electrodes for Water Oxidation

Abstract

Efficient and durable oxygen evolution reaction (OER) catalysts are highly required for the cost-effective generation of clean energy from water splitting. For the first time, an integrated OER electrode based on one-step direct growth of metallic iron-nickel sulfide nanosheets on FeNi alloy foils (denoted as FeNi S /FeNi) is reported, and the origin of the enhanced OER activity is uncovered in combination with theoretical and experimental studies. The obtained FeNi S /FeNi electrode exhibits highly catalytic activity and long-term stability toward OER in strong alkaline solution, with a low overpotential of 282 mV at 10 mA cm and a small Tafel slope of 54 mV dec . The excellent activity and satisfactory stability suggest that the as-made electrode provides an attractive alternative to noble metal-based catalysts. Combined with density functional theory calculations, exceptional OER performance of FeNi S /FeNi results from a combination of efficient electron transfer properties, more active sites, the suitable O evolution kinetics and energetics benefited from Fe doping. This work not only simply constructs an excellent electrode for water oxidation, but also provides a deep understanding of the underlying nature of the enhanced OER performance, which may serve as a guide to develop highly effective and integrated OER electrodes for water splitting.

Ultralow FeIII Ion Doping Triggered Generation of Ni3S2 Ultrathin Nanosheet for Enhanced Oxygen Evolution Reaction

“…The low Tafel slope of Fe 2.1% −Ni 3 S 2 /NF on one hand shows the good electrical contact between the Fe 2.1% −Ni 3 S 2 composites and the NF substrates, and on the other hand indicates the excellent mass transport properties of the inwards OH − diffusion and outwards oxygen bubbles diffusion . The Tafel slope of our Fe 2.1% −Ni 3 S 2 /NF is also better than that of frequently reported Ni‐based sulfide catalysts, such as 3D Ni 3 S 2 @NF (150 mV dec −1 ), Fe 11.8% −Ni 3 S 2 /NF (65.5 mV dec −1 ), Fe−Ni 3 S 2 /FeNi (54 mV dec −1 ), NiFeS/NF (74 mV dec −1 ), NiCoS/CF (96 mV dec −1 ) and other low‐cost catalysts (Table ). Moreover, the excellent mass transport properties of Fe 2.1% −Ni 3 S 2 /NF electrode are further reflected by multi‐current process testing.…”

“…As shown in Figure c, the high resolution Ni 2p spectrum, characteristic peaks of Ni 2p 3/2 and Ni 2p 1/2 at 856.0 and 873.6 eV together with their satellite peaks at 861.5 and 879.6 eV are found, confirming Ni is in Ni 2+ state ,,. Figure d shows the core‐level Fe 2p region spectrum and two peaks at 712.1 and 725.4 eV correspond to the Fe 2p 3/2 and Fe 2p 1/2 , respectively, indicating the presence of Fe(III) ,,. For the S 2p, the peaks at 162.2 eV and 163.5 eV are corresponding to S 2p 3/2 and S 2p 1/2 , respectively attributing to the S 2− in the Ni 3 S 2 (Figure e).…”

“…)% Fe(III), the Fe 2.1% −Ni 3 S 2 /NF electrode can reach 10 mA cm −2 at a much lower overpotential of only 213 mV, which is significantly lower than Ni 3 S 2 /NF and RuO 2 /NF (240 mV). Notably, such a low overpotential of 213 mV to achieve 10 mA cm −2 is much smaller than recently reported state‐of‐the‐art non‐noble metal sulfide OER catalysts, such as 3D Ni 3 S 2 @NF (340 mV), NiS 2 NWs/CFP (246 mV), Fe−Ni 3 S 2 /FeNi (282 mV), NiFeS/NF (231 mV), NiCo 2 S 4 /NF (260 mV) and other low‐cost catalysts (Table ).…”

“…For the S 2p, the peaks at 162.2 eV and 163.5 eV are corresponding to S 2p 3/2 and S 2p 1/2 , respectively attributing to the S 2− in the Ni 3 S 2 (Figure e). The additional peak at 168.4 eV can be ascribed to the sulfate species formed by the surface oxidation in air ,,,. The XPS results of Ni 3 S 2 /NF show the same configuration with that of Fe 2.1% −Ni 3 S 2 /NF (Figure S3), suggesting the doping of Fe 3+ into Ni 3 S 2 will not change the phase structure of Ni 3 S 2 .…”

Ultrathin Amorphous Iron–Nickel Boride Nanosheets for Highly Efficient Electrocatalytic Oxygen Production

“…[13] In this regard,t he in situ growth of nanostructurec atalysts on 3D Ni foam (NF) has been rarely studied for metal boride catalysts. In this regard, ab imetallic catalystc ombined with non-metallice lements to form selenides, [18] sulfides, [19] nitrides, [20] and phosphides [21] paves the way to synthesize numerous materials with different morphologies and structures,a nd facilitates synergistic effectsb etween iron and nickeld ue to efficient electrontransfer properties within thesen anostructures. [14] Low-cost nickel-based materials have been recognized for decades as the mosta ctive and stable earth-abundant materials against corrosion during the OER in alkaline media.…”