Phase engineering of nanomaterials provides a promising way to explore the phase-dependent physicochemical properties and various applications of nanomaterials. A general bottom-up synthesis method under mild conditions has always been challenging globally for the preparation of the semimetallic phasetransition-metal dichalcogenide (1T′-TMD) monolayers, which are pursued owing to their unique electrochemical property, unavailable in their semiconducting 2H phases. Here, we report the general scalable colloidal synthesis of nanosized 1T′-TMD monolayers, including 1T′-MoS 2 , 1T′-MoSe 2 , 1T′-WS 2 , and 1T′-WSe 2 , which are revealed to be of high phase purity. Moreover, the surfactantreliant stacking-hinderable growth mechanism of 1T′-TMD nano-monolayers was unveiled through systematic experiments and theoretical calculations. As a proof-of-concept application, the 1T′-TMD nano-monolayers are used for electrocatalytic hydrogen production in an acidic medium. The 1T′-MoS 2 nano-monolayers possess abundant in-plane electrocatalytic active sites and high conductivity, coupled with the contribution of the lattice strain, thus exhibiting excellent performance. Importantly, the catalyst shows impressive endurability in electroactivity. Our developed general scalable strategy could pave the way to extend the synthesis of other broad metastable semimetallic-phase TMDs, which offer great potential to explore novel crystal phase-dependent properties with wide application development for catalysis and beyond.
1T′-phase
MoS2 possesses excellent electrocatalytic
performance, but due to the instability of the thermodynamic metastable
phase, its actual electrocatalytic effect is seriously limited. Here,
we report a wet-chemical synthesis strategy for constructing rGO/1T′-MoS2/CeO2 heterostructures to improve the phase stability
of metastable 1T′ phase MoS2 monolayers. Importantly,
the rGO/1T′-MoS2/CeO2 heterostructure
exhibits excellent electrocatalytic hydrogen evolution reaction (HER)
performance, which is much better than the 1T′-MoS2 monolayers. The synergistic effects between CeO2 nanoparticles
(NPs) and 1T′-MoS2 monolayers were systematically
investigated. 1T′-MoS2 monolayers combined with
the cocatalyst of CeO2 NPs can produce lattice strain and
distortion on 1T′-MoS2 monolayers, which can tune
the energy band structure, charge transfer, and energy barriers of
hydrogen atom adsorption (ΔE
H),
leading to promotion of the phase activity and stability of 1T′-MoS2 monolayers for hydrogen production. Our work offers a feasible
method for the preparation of efficient HER electrocatalysts based
on the engineering phase stability of metastable materials.
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