Climate deterioration is closely related to the CO 2 concentration in atmosphere, which is considered one of the major environmental challenges we are facing today. It is urgent to take immediate actions to prevent further climate change. In comparison with post-combustion CO 2 capture technologies from flue gas, trace CO 2 capture directly from air is still a challenge but very important for both CO 2 control in atmosphere and air condition control in confined space. This review highlights recent research advances in the use of metal-organic frameworks (MOFs) for trace CO 2 capture, with the emphasis on employing amine functionalized MOFs and ultra-microporous MOFs. Herein, the reported strategies to enhance CO 2 adsorption capacity and selectivity by MOFs are categorized into three main directions, including the developments of MOFs with open metal sites, ultra-microporous MOFs, and amine functionalized MOFs. The mechanisms combined with trace CO 2 capture performance by these MOFs are discussed in detail, offering some promising adsorption solutions for future practical applications of MOF materials. In addition, the performance for CO 2 capture under humid conditions and the regenerability of these MOF adsorbents are revealed. In order to address major issues of capacity, selectivity and stability especially under humid conditions, precise construction and engineering of MOFs to achieve the optimized porous materials are needed.

In this work, an assembly of coating structures is generated for coated black carbon (BC) based on two different coating methods with limited tunable parameters. By defining typical parameters, the proposed coating structures show great agreement with the detailed morphologies of coated BC particles in the atmosphere. Our models can accurately reproduce the measured linear backscattering depolarization ratio (LDR). We noticed that BC with spherical coatings (Configuration E) has difficulty estimating large LDRs, while the ability to reproduce a large LDR is improved by making the coating structure slightly nonspherical (Configuration C). Our models also show a better performance in reproducing the laboratory‐measured absorption enhancement (Eabs), mass absorption/scattering cross sections, and absorption Ångström exponent than the simplified models. In addition, sizable uncertainties in the optical properties of coated BC with different coating configurations are found. The uncertainties in the LDR, Eabs, mass absorption cross section, and absorption Ångström exponent caused by the coating configurations can reach approximately 220%, 35%, 90%, and 20%, respectively. Therefore, complex coating structures should be carefully considered. In this work, various coating structures are represented by limited tunable parameters, which is beneficial to the parameterization of the optical properties of BC with a complex coating structure. Our models can also provide tools for exploring the agreement between calculations and measurements.

Progress in natural gas storage with wet adsorbents is presented. The storage mechanism switched from adsorption for adsorbed natural gas (ANG) to hydrate formation when wet adsorbents were used. The activated carbon with a pore size of 1.6-3 nm was shown more suitable for the wet storage method, and a larger than 40 wt % gravimetric storage capacity and a deliverable capacity of more than 150 (v/v) were experimentally observed under conditions of 273-283 K and pressure ca. 8 MPa. The stored amount in wet carbon is 2 times higher than that of adsorbed and 1.5 times than that of compressed at the indicated conditions. All of the inherent technical drawbacks of ANG were overcome, and the storage pressure reduced more than half compared to compressed natural gas (CNG). Both investment and energy costs of fuel are expected to reduce, and the safety of the natural gas (NG) vehicle will improve radically.

No abstract

No abstract

Single-crystalline magnesium oxide (MgO) is an attractive material of substrates for hightemperature devices and high-temperature superconducting films. However, it is difficult to achieve the direct bonding of MgO/MgO because of its high brittleness and hardness, as well as the weak bonding force between the crystal faces. In this paper, we presented a hydrophilic direct bonding method of MgO by using two-step surface activation and a high-temperature annealing process. The bonding strengths under different annealing temperatures, pressures and times were measured. A high bonding strength (∼7 MPa) and a fine bonding interface without any microcracks and voids were obtained after annealing at 1200 • C, 140 min and 4 MPa. The bonding interface was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The bonding mechanism of MgO/MgO was also clearly clarified. For the demo application, a MgO sealed cavity was formed by using the direct bonding method which is commonly used in the microelectromechanical systems (MEMS) devices for harsh environment applications. INDEX TERMS MgO single crystal, direct bonding, surface activation, high temperature annealing, bonding interface.

Developing advanced porous materials with industrial potential to separate multicomponent gas mixtures that are structurally similar is a crucial but challenging task. Here, we report the efficient one-step separation of...

No abstract