Recent Development of Moisture-Enabled-Electric Nanogenerators.

Power generation by converting energy from the ambient environment has been considered a promising strategy for developing decentralized electrification systems to complement the electricity supply for daily use. Wet gases, such as water evaporation or moisture in the atmosphere, can be utilized as a tremendous source of electricity by emerging power generation devices, that is, moisture-enabled-electric nanogenerators (MEENGs). As a promising technology, MEENGs provided a novel manner to generate electricity by harvesting energy from moisture, originating from the interactions between water molecules and hydrophilic functional groups. Though the remarkable progress of MEENGs has been achieved, a systematic review in this specific area is urgently needed to summarize previous works and provide sharp points to further develop low-cost and high-performing MEENGs through overcoming current limitations. Herein, the working mechanisms of MEENGs reported so far are comprehensively compared. Subsequently, a systematic summary of the materials selection and fabrication methods for currently reported MEENG construction is presented. Then, the improvement strategies and development directions of MEENG are provided. At last, the demonstrations of the applications assembled with MEENGs are extracted. This work aims to pave the way for the further MEENGs to break through the performance limitations and promote the popularization of future micron electronic self-powered equipment.

Hydrazine Hydrate Intercalated 1T-Dominant MoS2 with Superior Ambient Stability for Highly Efficient Electrocatalytic Applications.

Metallic 1T-phase MoS2 exhibits superior hydrogen evolution reaction (HER) performance than natural 2H-phase MoS2 owing to its higher electrical conductivity and abundance of active sites. However, the reported 1T-MoS2 catalysts usually suffer from extreme instability, which results in quick phase transformation at ambient conditions. Herein, we present a facile approach to engineer the phase of MoS2 by introducing intercalated hydrazine. Interestingly, the as-synthesized 1T-dominant MoS2 sample demonstrates excellent ambient stability without noticeable degradation for 3 months. Additionally, the 1T-dominant MoS2 exhibits superior electrical conductivity (∼700 times higher than that of 2H-MoS2) and improved electrochemical catalytic performance (current density ∼12 times larger than that of 2H-MoS2 at an overpotential of 300 mV vs the reversible hydrogen electrode, RHE). Through experimental characterizations and density functional theory (DFT) calculation, we conclude that the stabilization of the metallic phase could be attributed to the electron donation from hydrazine molecules to the adjacent Mo atoms. The phase control strategy in this work provides a guideline to develop other highly efficient and stable two-dimensional (2D) electrocatalysts.

Random growth networks with exponential degree distribution.

A great variety of complex networks can be well represented as random graphs with some constraints: for instance, a provided degree distribution, a smaller diameter, and a higher clustering coefficient. Among them, the degree distribution has attracted considerable attention from various science communities in the last few decades. In this paper, we focus mainly on a family of random graphs modeling complex networks that have an exponential degree distribution; i.e., P(k)∼ exp(αk), where k is the degree of a vertex, P(k) is a probability for choosing randomly a vertex with degree equal to k, and α is a constant. To do so, we first introduce two types of operations: type-A operation and type-B operation. By both the helpful operations, we propose an available algorithm A for a seminal model to construct exactly solvable random graphs, which are able to be extended to a graph space S(p,pc,t) with probability parameters p and pc satisfying p+pc=1. Based on the graph space S(p,pc,t), we discuss several topological structure properties of interest on each member N(p,pc,t) itself and find model N(p,pc,t) to exhibit the small-world property and assortative mixing. In addition, we also report a fact that in some cases, two arbitrarily chosen members might have completely different other topological properties, such as the total number of spanning trees, although they share a degree distribution in common. Extensive experimental simulations are in strong agreement with our analytical results.

Ceramic tiles with black pigment made from stainless steel plant dust: Physical properties and long-term leaching behavior of heavy metals.

UNLABELLED: Stainless steel plant dust is a hazardous by-product of the stainless steelmaking industry. It contains large amounts of Fe, Cr, and Ni, and can be potentially recycled as a raw material of inorganic black pigment in the ceramic industry to reduce environmental contamination and produce value-added products. In this paper, ceramic tiles prepared with black pigment through recycling of stainless steel plant dust were characterized in terms of physical properties, such as bulk density, water absorption, apparent porosity, and volume shrinkage ratio, as well as the long-term leaching behavior of heavy metals (Cr, Ni, Pb, Cd, and Zn). The results show that good physical properties of ceramic tiles can be obtained with 8% pigments addition, sample preparation pressure of 25 MPa, and sintering at 1200 ºC for 30 min. The major controlling leaching mechanism for Cr and Pb from the ceramic tiles is initial surface wash-off, while the leaching behavior of Cd, Ni, and Zn from the stabilized product is mainly controlled by matrix diffusion. The reutilization process is safe and effective to immobilize the heavy metals in the stainless steel plant dust. IMPLICATIONS: Stainless steel plant dust is considered as a hazardous material, and it can be potentially recycled for black pigment preparation in the ceramic industry. This paper provides the characteristics of the ceramic tiles with black pigment through recycling stainless steel plant dust, and the long-term leaching behavior and controlling leaching mechanisms of heavy metals from the ceramic tile. The effectiveness of the treatment process is also evaluated.