Direct Synthesis of Stable 1T‐MoS₂ Doped with Ni Single Atoms for Water Splitting in Alkaline Media

Abstract

Metallic MoS2 (i.e., 1T‐MoS2) is considered as the most promising precious‐metal‐free electrocatalyst with outstanding hydrogen evolution reaction (HER) performance in acidic media comparable to Pt. However, sluggish kinematics of HER in alkaline media and its inability for the oxygen evolution reaction (OER), hamper its development as bifunctional catalysts. The instability of 1T‐MoS2 further impedes its applications for scaling up, calling an urgent need for simple synthesis to produce stable 1T‐MoS2. In this work, the challenge of 1T‐MoS2 synthesis is first addressed using a direct one‐step hydrothermal method by adopting ascorbic acid. 1T‐MoS2 with flower‐like morphology is obtained, and transition metals (Ni, Co, Fe) are simultaneously doped into 1T‐MoS2. Ni‐1T‐MoS2 achieves an enhanced bifunctional catalytic activity for both HER and OER in alkaline media, where the key role of Ni doping as single atom is proved to be essential for boosting HER/OER activity. Finally, a Ni‐1T‐MoS2||Ni‐1T‐MoS2 electrolyzer is fabricated, reaching a current density of 10 mA cm−2 at an applied cell voltage of only 1.54 V for overall water splitting.

Recent Progress in Phase Regulation, Functionalization, and Biosensing Applications of Polyphase MoS2

“…In one of their works, Wang et al introduced ascorbic acid (AA) in a simple one-step hydrothermal process, and found that flower-shaped 1T-MoS 2 could be collected at low temperatures and 2H-MoS 2 at high temperatures (>200 °C) (Figure 9C). [133] The XRD patterns of the product samples showed that the interlayer distance of MoS 2 was 9.65 Å and that of 2H was 6.3 Å. The synthesis mechanism of 1T phase was as follows: AA was dehydrogenated during the reaction to generate dehydrogenated ascorbic acid, which was inserted between MoS 2 layers and prompted and its XRD patterns.…”

“…Ni-, Co-, Fe-doped flower-like 1T-MoS 2 were obtained by introducing transition metals. [133] The results showed that Ni1T-MoS 2 had enhanced catalytic activity for both HER and OER reactions in alkaline medium, and the atomic doping of Ni was proven to be the key for HER/OER performance improvement. In Gudal et al's study, a phosphorus-doped ultrathin 1T-copper molybdenum disulfide (P1T-CMS) multifunctional electrocatalyst for water separation was developed, and the catalyst showed good catalytic effect for both HER and OER.…”

“…Reproduced with permission. [133] Copyright 2022, Wiley-VCH. D) Illustration of 1T-MoS 2 a spatially confined template method.…”

“…These characteristics were conducive to the fast interaction between electrodes and biomolecules. In order to improve the electronic conductivity and electrochemical activity of MoS 2 , various attempts have been implemented, including phase transition, [123] heteroatomic doping, [133,227] reduction of MoS 2 , [226] and development of new composite materials. [228] In the electrochemical sensing examples mentioned above, MoS 2 not only serves as an electrocatalytic material that interacts with the substrate, but also acts as an electron transfer medium to amplify the reaction signal.…”

“…C) Illustration of hydrothermal synthesis of 1T-MoS 2 (AA present) and 2H-MoS 2 (AA absent). Reproduced with permission [133]. Copyright 2022, Wiley-VCH.…”