One-step in-situ sprouting high-performance NiCoSxSey bifunctional catalysts for water electrolysis at low cell voltages and high current densities

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 435; p. 134859
• Main Authors: Ma, Shunfeng, Huang, Jun, Zhang, Cheng, Chen, Guangliang, Chen, Wei, Shao, Tao, Li, Tongtong, Zhang, Xianhui, Gong, Teng, Ostrikov, Kostya Ken
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2022
• Subjects: Bifunctional electrocatalysts; Clean hydrogen energy; In-situ nanostructuring; Overall water splitting; Transition metal sulfur-selenide; Transition metal sulfur-selenide; In-situ nanostructuring; Overall water splitting; Bifunctional electrocatalysts; Clean hydrogen energy
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.134859

High-performance bi-functional water splitting electrocatalysts made of NiCoSxSey nanosheets are sprouted in situ on the Ni-Co foam (NCF). The multiple phases of NiCoSxSey nanosheets cause the high activity, ultra-fast reaction kinetics, outstanding stability, and high H2/O2 production rates for both HER and OER at industry-relevant current densities. The high activity is confirmed by the low overpotentials of 39 and 345 mV for HER, and 235 and 427 mV for OER at 10 and 1000 mA cm−2 current densities in an alkaline medium, respectively. The stable operation over 100h with j100 or 24h with j500 is achieved. [Display omitted] •NiCo sulfur-selenide bifunctional water splitting catalyst sprouted from NiCo electrode;•Multiphase heterostructure is formed by nano-interfaced phases on NiCoSxSey nanosheets;•Rich catalytically active sites on the interfaces between the metal sulfur-selenide phases;•Extraordinary HER and OER activity and stability at industry-relevant current density;•The cell voltage values for overall water splitting outperform noble metal cell systems. Engineering high-performance non-precious metal-based bifunctional catalysts for water splitting are still facing some issues especially at industry-relevant current densities. Here, this challenge is addressed by the new approach to grow extra-stable nickel cobalt sulfur-selenide (NiCoSxSey) nanosheet catalysts on nickel–cobalt foam (NCF), and the obtained NiCoSxSey affords the low overpotentials of 345 mV for hydrogen evolution reaction (HER) and 427 mV for oxygen evolution reaction (OER) at 1000 mA cm−2 (j1000). Meanwhile, the NiCoSxSey/NCF also shows the excellent long-term stability for both HER and OER processes driven with j100 for 100 h and j500 for 24 h. In addition, the cell voltage assembled with NiCoSxSey/NCF is only 1.84 V at j500 in 1 M KOH, and the I-t characteristic shows a low decay (<3 %) after 50 h operation at j100. The ab-initio simulations reveal that the CoS2-CoSe2, Ni3S2-Ni3Se2 and CoS2-Ni3Se2 interfaces are the active sites for HER.