Molybdenum disulfide (MoS₂) ultrathin nanosheets, as a well-known inorganic two dimensional (2D) material with a graphene-like structure, has attracted tremendous attention due to its unique microscopic and macroscopic properties brought by the confinement of charge and heat transfer upon the basal plane. However, as the prototype Mott-insulator, its relatively low conductivity and carrier concentration still greatly hamper its wide applications. Here, we developed a novel intralayer vanadium-doping strategy to produce semimetallic vanadium-doped MoS₂ (VMS) ultrathin nanosheets with less than five S-(V, Mo)-S atomic layers, as a new inorganic 2D material. By incorporation of intralayer vanadium atoms, fine regulation of intrinsic electrical properties within the pristine MoS₂ structure has been successfully realized, achieving semimetallic MoS₂-based 2D materials with tunable conductivity and higher carrier concentration for the first time. Benefiting from the enhanced in-plane conductivity, the improved carrier concentration as well as the shortened electron transfer paths, the semimetal-like VMS nanosheet have enhanced catalytic activity with an overpotential of 0.13 V and a smaller Tafel slope, exhibiting enhanced catalytic performance compared with that of a pure MoS₂ system. The intralayer doping in the 2D structure opens a new avenue in building highly efficient catalysts through the regulation of their intrinsic electrical properties, and also gives a new perspective for enlarging the design space of 2D materials.

The effect of lanthanum (La) content on the phase transformation of Pb1−3x/2Lax(Zr0.42Sn0.40Ti0.18)O3 (PLZST 100x/42/40/18, 0 ≤ x ≤ 0.06) ceramics was investigated by the dielectric and ferroelectric properties. The base composition PLZST 0/42/40/18 located in the ferroelectric (FE) rhombohedral phase region. As x increased, the compositions showed successively FE and antiferroelectric (AFE) state at room temperature, and their peak temperatures (Tmax) decreased gradually in line as Tmax = 162.21‐1507x. Evidence was presented that there were two dielectric anomalies in PLZST 2/42/40/18, which were corresponding to the FE‐AFE and AFE‐paraelectric (PE) phase transformations, respectively. With increasing the dc bias fields, the two phases merged into one. PLZST 3/42/40/18 showed AFE characteristics with the first loop outside of the second loop and there was only one dielectric inflection. The critical lanthanum content occurred at x = 0.03 from the dielectric temperature spectra and hysteresis loops. Furthermore increase in La above 0.03, these compositions showed typical antiferroelectric behaviors with double hysteresis loops. The stored energy properties of the three compositions (PLZST 4/42/40/18, 5/42/40/18 and 6/42/40/18) displayed different temperature dependencies from room temperature to 140°C (over their respective Tmax). Comparing the above results with previous investigations on PLZSTs, some questions were discussed.