Metallic-phase MoS2 (M-MoS2) is metastable and does not exist in nature. Pure and stable M-MoS2 has not been previously prepared by chemical synthesis, to the best of our knowledge. Here we report a hydrothermal process for synthesizing stable two-dimensional M-MoS2 nanosheets in water. The metal–metal Raman stretching mode at 146 cm−1 in the M-MoS2 structure, as predicted by theoretical calculations, is experimentally observed. The stability of the M-MoS2 is associated with the adsorption of a monolayer of water molecules on both sides of the nanosheets, which reduce restacking and prevent aggregation in water. The obtained M-MoS2 exhibits excellent stability in water and superior activity for the hydrogen evolution reaction, with a current density of 10 mA cm−2 at a low potential of −175 mV and a Tafel slope of 41 mV per decade.

Highly uniform core/double-shell-structured β-NaYF4:Er(3+),Yb(3+)@SiO2@TiO2 hexagonal sub-microprisms are prepared and employed in dye-sensitized solar cells (DSCs) internally. This work paves a facile way to enable the most-efficient upconversion material (β-NaYF4:Er(3+),Yb(3+)) to be used as scattering and upconversion centers in the photoelectrode of a DSC.

The hydrogen evolution reaction in an alkaline environment using a non‐precious catalyst with much greater efficiency represents a critical challenge in research. Here, a robust and highly active system for hydrogen evolution reaction in alkaline solution is reported by developing MoS2 nanosheet arrays vertically aligned on graphene‐mediated 3D Ni networks. The catalytic activity of the 3D MoS2 nanostructures is found to increase by 2 orders of magnitude as compared to the Ni networks without MoS2. The MoS2 nanosheets vertically grow on the surface of graphene by employing tetrakis(diethylaminodithiocarbomato)molybdate(IV) as the molybdenum and sulfur source in a chemical vapor deposition process. The few‐layer MoS2 nanosheets on 3D graphene/nickel structure can maximize the exposure of their edge sites at the atomic scale and present a superior catalysis activity for hydrogen production. In addition, the backbone structure facilitates as an excellent electrode for charge transport. This precious‐metal‐free and highly efficient active system enables prospective opportunities for using alkaline solution in industrial applications.

Rationally constructing inexpensive sulfur hosts that have high electronic conductivity, large void space for sulfur, strong chemisorption, and rapid redox kinetics to polysulfides is critically important for their practical use in lithium–sulfur (Li–S) batteries. Herein, we have designed a multifunctional sulfur host based on yolk–shelled Fe2N@C nanoboxes (Fe2N@C NBs) through a strategy of etching combined with nitridation for high-rate and ultralong Li–S batteries. The highly conductive carbon shell physically confines the active material and provides efficient pathways for fast electron/ion transport. Meanwhile, the polar Fe2N core provides strong chemical bonding and effective catalytic activity for polysulfides, which is proved by density functional theory calculations and electrochemical analysis techniques. Benefiting from these merits, the S/Fe2N@C NBs electrode with a high sulfur content manifests a high specific capacity, superior rate capability, and long-term cycling stability. Specifically, even after 600 cycles at 1 C, a capacity of 881 mAh g–1 with an average fading rate of only 0.036% can be retained, which is among the best cycling performances reported. The strategy in this study provides an approach to the design and construction of yolk–shelled iron-based compounds@carbon nanoarchitectures as inexpensive and efficient sulfur hosts for realizing practically usable Li–S batteries.

Control over porosity and exposed highly reactive facets is challenging in the area of materials science. Materials with high porosity and reactivity of exposed facets are favorable candidates in catalysis and energy storage. Here we demonstrate a facile template-free route to synthesize nanoporous LiMn 2 O 4 nanosheets composed of single-crystalline LiMn 2 O 4 nanorods with exposed {111} facets via an in situ lithiation of ultrathin MnO 2 nanosheets. Nearly 100% of the initial capacity can be retained after 500 cycles at a 1C discharge rate using the nanoporous nanosheets as a cathode, whereas at a discharge rate of 25C, the capacity retention is about 86% of the initial capacity after 500 cycles. The durable cycling performance and high capacity retention can be attributed to the intrinsic highly oriented crystallinity, two-dimensional (2D) nanoporosity and exposed {111} facet of the nanosheet cathode.