Efficient Hydrogen Evolution Reaction Catalysis in Alkaline Media by All‐in‐One MoS₂ with Multifunctional Active Sites

Abstract

MoS becomes an efficient and durable nonprecious-metal electrocatalyst for the hydrogen evolution reaction (HER) when it contains multifunctional active sites for water splitting derived from 1T-phase, defects, S vacancies, exposed Mo edges with expanded interlayer spacings. In contrast to previously reported MoS -based catalysts targeting only a single or few of these characteristics, the all-in-one MoS catalyst prepared herein features all of the above active site types. During synthesis, the intercalation of in situ generated NH molecules into MoS sheets affords ammoniated MoS (A-MoS ) that predominantly comprises 1T-MoS and exhibits an expanded interlayer spacing. The subsequent reduction of A-MoS results in the removal of intercalated NH and H S to form an all-in-one MoS with multifunctional active sites mentioned above (R-MoS ) that exhibits electrocatalytic HER performance in alkaline media superior to those of all previously reported MoS -based electrocatalysts. In particular, a hybrid MoS /nickel foam catalyst outperforms commercial Pt/C in the practically meaningful high-current region (>25 mA cm ), demonstrating that R-MoS -based materials can potentially replace Pt catalysts in practical alkaline HER systems.

Atomic Arrangement in Metal‐Doped NiS2 Boosts the Hydrogen Evolution Reaction in Alkaline Media

“…Thet urnover frequencies (TOF) per metal site are calculated based on the hypothesis that all the metal atoms in the catalysts formed active site and all of them were accessible to the electrolyte (Supporting Information). [29][30][31] TheT OFs of Co-NiS 2 NSs are 0.55 H 2 per sa nd 4.1 H 2 per sa to verpotentials of 100 and 200 mV, respectively.T OF plots against the applied overpotential are summarized in Figure 4f, Table S3.…”

“…Thethiocyanate ion poisoning experiments identify that after Co doping the enhanced content of e g 1 and Ni 3+ are responsible for the outstanding HER performance of the Co-NiS 2 NSs catalysts.Importantly,the Co-NiS 2 NSs catalysts exhibit unprecedented TOFs (TOFs per Ni atom of 0.55 and 4.1 s À1 at an overpotential of 100 and 200 mV,respectively) in alkaline media, which are superior to recently reported HER catalysts with breakthrough performance. [29][30][31] This in-depth understanding of atomic rearrangement in doping strategy offers ag uideline for the fabrication of multifunctional catalysts.…”

Hatted 1T/2H‐Phase MoS2 on Ni3S2 Nanorods for Efficient Overall Water Splitting in Alkaline Media

“…As imilar XRD pat-tern for the S-Ni@NF sample is shown in Figure S2 (Supporting Information), except for the typical MoS 2 peak, indicating that the appearanceo fM oS 2 does not interferew itht he formation of Ni 3 S 2 on the Ni foam matrix. [3] The peaks at 198, 235, 285,a nd 336 cm À1 were attributedt ot he J 1 ,J 2 ,E 1g ,a nd J 3 bands of the 1T-phase MoS 2 , [35,41,43] and the peaks at 379 and 404 cm À1 were attributed to the E 1 2g andA 1g vibrational modes, respectively, of the 2H-phase MoS 2 . [3] The peaks at 198, 235, 285,a nd 336 cm À1 were attributedt ot he J 1 ,J 2 ,E 1g ,a nd J 3 bands of the 1T-phase MoS 2 , [35,41,43] and the peaks at 379 and 404 cm À1 were attributed to the E 1 2g andA 1g vibrational modes, respectively, of the 2H-phase MoS 2 .…”

“…As shown in Figure 2b,t he Ramans pectrumo ft he 0.2-A@NF sample shows characteristic peaks at 197, 218, 298, 320, and 346 cm À1 ,w hich were associated with the Ni 3 S 2 bands. [36,43,44] Figure S3 (SupportingI nformation) shows the Raman spectra for the S-Ni@NF sample,w hich provedt he presence of the peaks attributed to Ni 3 S 2 .T he chemicals tates of the elements were investigated by X-ray photoelectron spectroscopy. [36,43,44] Figure S3 (SupportingI nformation) shows the Raman spectra for the S-Ni@NF sample,w hich provedt he presence of the peaks attributed to Ni 3 S 2 .T he chemicals tates of the elements were investigated by X-ray photoelectron spectroscopy.…”

“…Nevertheless, this kind of structure is not as good as the hatted nanorods because of the relatively inadequate conductivity and the lack of the 1T-MoS 2 phase. [43] Furthermore, the morphology and electrocatalytic activity of the hatted MoS 2 -Ni 3 S 2 nanorods can be adjusted by controlling the addition of aqueous ammonia. However,2 H-MoS 2 suffers from chemically inert basal planes, deficienta ctive sites, and poor conductivity,r esulting in limitedu tilization in electrocatalytic water splitting.…”