Figure 1a). [2] The metastable 1T MoS2 was reported to have A-b-C layers with edge-sharing [MoS6] octahedron (see Figure 1b), which was derived from electron diffraction [3] and powder X-ray pattern. [4] But the crystal structure of 1T MoS2 has never been collected in the Inorganic Crystal Structure Database (ICSD) due to the lack of a strict structural refinement.Although the single-layer 1T MoS2 has been prepared by using various synthetic methods, [5] the obtained nanosheets always coexist with 2H, 1T, and 1T' phases. The maximal content of 1T/1T' domains have been reported to be up to 80% which was evaluated by XPS measurements.[5b] The 1T/1T' MoS2 phases were observed to start the transformation to thermodynamically more stable 2H phase at around 100 C and be completely converted into 2H phase at 300 C. [6] It was recently reported that 1T/1T' MoS2 domains can be stabilized by electron doping. [7] 2H MoS2 intrinsically behaves as a semiconductor with a band gap of 1.2-1.9 eV, [8] which is consistent with the closeshell electronic configuration of Mo 4+ 4d 2 (dz 2 , dx 2 -y 2 ) in a trigonal prismatic coordination environment (Figure 1a). [9] Previously reported superconductivity in the MoS2 system is based on electron injection to the Fermi surface of 2H MoS2 [9] shown in Figure 1b, whose two electrons are filled in the t states and may also become itinerant electrons. Anomalous superconductivity has recently been reported in the structure-related 1T' MoTe2 at a very low Tc of about 0.1 K.[12] The density functional calculations predicted the metallicity of 1T MoS2. [13] However, the sample of MoS2 nanosheets coexisting with 1T/1T' and 2H phases was found to have a semiconducting behavior. [14] Moreover, the superconductivity of 1T MoS2 has never been discovered yet.So far, it is very important and urgent to synthesize single crystals of 1T-MoS2 for re-determining single crystal structure and investigating intrinsic physical properties. Here, we reported a modified strategy derived from the literature The preparation of 1T-MoS2 started from the intercalated compound LiMoS2, whose synthesis process was described by our previous results. [15] The oxidation processes of LiMoS2 crystals were divided into two steps, in which the corresponding reactions happen as follow:In the first step, lithium atoms undergo the hydration process, which expands the interlayer distance of MoS2. Figure S1a shows the PXRD pattern of as-obtained Li1-x(H2O)yMoS2, which corresponds to 12.149 Å of the d value along the c direction. Expanded layer spacing reduces the interactions between sulfur atoms and lithium atoms, which promotes the removal of lithium ion in the second redox process. Moreover, the deintercalation of Li ions causes fewer damages on the crystal structure of 1T MoS2 compared with that caused by the deintercalation of K ions.[3], [4] As illustrated in Figure 1b, the 1T-MoS2 crystallizes in the trigonal space group P-3m1. The unit cell consists of one independent Mo site and one independent S site. Each layer...

The synthesis of alloys with long-range atomic-scale ordering (ordered intermetallics) is an emerging field of nanochemistry. Ordered intermetallic nanoparticles are useful for a wide variety of applications such as catalysis, superconductors, and magnetic devices. However, the preparation of nanostructured ordered intermetallics is challenging in comparison to disordered alloys, hindering progress in material development. Herein, we report a process for converting colloidally synthesized ordered intermetallic PdBi2 to ordered intermetallic Pd3Bi nanoparticles under ambient conditions by electrochemical dealloying. The low melting point of PdBi2 corresponds to low vacancy formation energies, which enables the facile removal of the Bi from the surface while simultaneously enabling interdiffusion of the constituent atoms via a vacancy diffusion mechanism under ambient conditions. The resulting phase-converted ordered intermetallic Pd3Bi exhibits 11 times and 3.5 times higher mass activity and high methanol tolerance for the oxygen reduction reaction compared with Pt/C and Pd/C, respectively, which is the highest reported for a Pd-based catalyst, to the best of our knowledge. These results establish a key development in the synthesis of noble-metal-rich ordered intermetallic phases with high catalytic activity and set forth guidelines for the design of ordered intermetallic compounds under ambient conditions.

We prepare group VI transitional metal dichalcogenides (TMDs, or MX) from the 1T phase with quantum-sized and monolayer features via a quasi-full electrochemical process. The resulting two-dimensional (2D) MX (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-MX lattice (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 MX crystals. Because of their high proportion of metallic 1T phase and sufficient active sites induced by the small lateral size, the 2D 1T-MoS QDs show excellent hydrogen evolution reactivity (with a typical η of 92 mV, Tafel slope of 44 mV/dec, and J of 4.16 × 10 A/cm). This electrochemical route toward 2D QDs might help boost the development of 2D materials in energy-related areas.

The HER performance of MoS2 is enhanced dramatically by doping single Ni atoms into Mo sites.

Figure 1a). [2] The metastable 1T MoS2 was reported to have A-b-C layers with edge-sharing [MoS6] octahedron (see Figure 1b), which was derived from electron diffraction [3] and powder X-ray pattern. [4] But the crystal structure of 1T MoS2 has never been collected in the Inorganic Crystal Structure Database (ICSD) due to the lack of a strict structural refinement.Although the single-layer 1T MoS2 has been prepared by using various synthetic methods, [5] the obtained nanosheets always coexist with 2H, 1T, and 1T' phases. The maximal content of 1T/1T' domains have been reported to be up to 80% which was evaluated by XPS measurements.[5b] The 1T/1T' MoS2 phases were observed to start the transformation to thermodynamically more stable 2H phase at around 100 C and be completely converted into 2H phase at 300 C. [6] It was recently reported that 1T/1T' MoS2 domains can be stabilized by electron doping. [7] 2H MoS2 intrinsically behaves as a semiconductor with a band gap of 1.2-1.9 eV, [8] which is consistent with the closeshell electronic configuration of Mo 4+ 4d 2 (dz 2 , dx 2 -y 2 ) in a trigonal prismatic coordination environment (Figure 1a). [9] Previously reported superconductivity in the MoS2 system is based on electron injection to the Fermi surface of 2H MoS2 [9] shown in Figure 1b, whose two electrons are filled in the t states and may also become itinerant electrons. Anomalous superconductivity has recently been reported in the structure-related 1T' MoTe2 at a very low Tc of about 0.1 K.[12] The density functional calculations predicted the metallicity of 1T MoS2. [13] However, the sample of MoS2 nanosheets coexisting with 1T/1T' and 2H phases was found to have a semiconducting behavior. [14] Moreover, the superconductivity of 1T MoS2 has never been discovered yet.So far, it is very important and urgent to synthesize single crystals of 1T-MoS2 for re-determining single crystal structure and investigating intrinsic physical properties. Here, we reported a modified strategy derived from the literature The preparation of 1T-MoS2 started from the intercalated compound LiMoS2, whose synthesis process was described by our previous results. [15] The oxidation processes of LiMoS2 crystals were divided into two steps, in which the corresponding reactions happen as follow:In the first step, lithium atoms undergo the hydration process, which expands the interlayer distance of MoS2. Figure S1a shows the PXRD pattern of as-obtained Li1-x(H2O)yMoS2, which corresponds to 12.149 Å of the d value along the c direction. Expanded layer spacing reduces the interactions between sulfur atoms and lithium atoms, which promotes the removal of lithium ion in the second redox process. Moreover, the deintercalation of Li ions causes fewer damages on the crystal structure of 1T MoS2 compared with that caused by the deintercalation of K ions.[3], [4] As illustrated in Figure 1b, the 1T-MoS2 crystallizes in the trigonal space group P-3m1. The unit cell consists of one independent Mo site and one independent S site. Each layer...