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We prepare group VI transitional metal dichalcogenides (TMDs, or MX2) from the 1T phase with quantum-sized and monolayer features viaa quasi-full electrochemical process. The resulting two-dimensional (2D) MX2(M = W, Mo; X = S, Se) quantum dots (QDs) are ca. 3.0–5.4 nm in size with a high 1T phase fraction of ca. 92%–97%. We attribute this to the high Li content intercalated in the 1T-MX2lattice (mole ratio of Li:M is over 2:1), which is achieved by an increased lithiation driving force and a reduced electrochemical lithiation rate (0.001 A/g). The high Li content not only promotes the 2H → 1T phase transition but also generates significant inner stress that facilitates lattice breaking for MX2crystals. Because of their high proportion of metallic 1T phase and sufficient active sites induced by the small lateral size, the 2D 1T-MoS2QDs show excellent hydrogen evolution reactivity (with a typical η10of 92 mV, Tafel slope of 44 mV/dec, and J0of 4.16 × 10–4A/cm2). This electrochemical route toward 2D QDs might help boost the development of 2D materials in energy-related areas.

This paper reports a versatile method to fabricate robust carbon/metal hybrids with ultrasmall particle and highly developed porous structure through a scalable and facile way. Alginate is used as the precursor for it could perform cross-linking reaction with different polyvalent metal ions to form gels. After simple freeze-drying and carbonization of the alginate-derived gels, we obtained the carbon/metal hybrids with fine nanostructure. Eleven kinds of metal ions were introduced to form gels and five kinds of the gels were carbonized to produce the carbon/metal hybrids. By adjusting the reaction condition, we could tune the size of the nanoparticles in the obtained hybrids. The obtained SnO2/C hybrid shows outstanding specific capacity, rate performance, and long cycle life when it is used as the anode materials of lithium ion batteries. The ultrasmall active nanoparticles were uniformly dispersed within an interconnected pore framework. It ensured a short diffusion and transportation distance of electrolyte ions to the surfaces of active nanoparticles. In addition, the robust carbon framework comprises of quasigraphitic carbon layers. It contributed to the high rate performance by providing excellent conductive pathways for electrons within the electrodes. This work provides a general method for fabrication of carbon/metal (oxide) hybrids with fine nanostructure for application in energy storage.