Huajun Yang

Cation-Exchanged Zeolitic Chalcogenides for CO2 Adsorption

We report here the intrinsic advantages of a special family of porous chalcogenides for CO2 adsorption in terms of high selectivity of CO2/N2, large uptake capacity, and robust structure due to their first-ever unique integration of the chalcogen-soft surface, high porosity, all-inorganic crystalline framework, and the tunable charge-to-volume ratio of exchangeable cations. Although tuning the CO2 adsorption properties via the type of exchangeable cations has been well-studied in oxides and MOFs, little is known about the effects of inorganic exchangeable cations in porous chalcogenides, in part because ion exchange in chalcogenides can be very sluggish and incomplete due to their soft character. We have demonstrated that, through a methodological change to progressively tune the host-guest interactions, both facile and nearly complete ion exchange can be accomplished. Herein, a series of cation-exchanged zeolitic chalcogenides (denoted as M@RWY) were studied for the first time for CO2 adsorption. Samples were prepared through a sequential ion-exchange strategy, and Cs+-, Rb+-, and K+-exchanged samples demonstrated excellent CO2 adsorption performance. Particularly, K@RWY has the superior CO2/N2 selectivity with the N2 adsorption even undetected at either 298 or 273 K. It also has the large uptake of 6.3 mmol/g (141 cm3/g) at 273 K and 1 atm with an isosteric heat of 35-41 kJ mol-1, the best among known porous chalcogenides. Moreover, it permits a facile regeneration and exhibits an excellent recyclability, as shown by the multicycling adsorption experiments. Notably, K@RWY also demonstrates a strong tolerance toward water.

Two Unique Crystalline Semiconductor Zeolite Analogues Based on Indium Selenide Clusters

Developing the structural diversity of microporous zeolitic frameworks with integrated semiconducting properties is promising but remains a challenge. Reported here are two unique crystalline semiconductor zeolite analogues constructed from two kinds of indium selenide clusters with augmented ctn and zeolite-type sod networks. The intrinsic semiconducting nature in these In-Se domains gives rise to pore-size-dependent and visible-light-driven photocatalytic activity for organic dye degradation.

Assembly of supertetrahedral clusters into a Cu–In–S superlattice via an unprecedented vertex–edge connection mode

We demonstrated here the first case of a vertex–edge connection mode in a three-dimensional open-framework chalcogenide built from the largest known T5 cluster. Such connection relies on a tri-coordinated edge sulfur atom, which serves as the linkage to bridge two adjacent T5 clusters. The architecture of the resulting structure can be classified as the infinite order of super-supertetrahedral T5 clusters (T5, ∞).

An Unusual Metal Chalcogenide Zeolitic Framework Built from the Extended Spiro-5 Units with Supertetrahedral Clusters as Nodes

Reported here is a new metal chalcogenide semiconductor with the double-interpenetrated zeolitic nabesite framework, which is constructed by the rare extended spiro-5 units with supertetrahedral clusters serving as building units. Different from the TO4-based simple spiro-5 unit frequently observed in oxide-based zeolites, the extended spiro-5 unit composed of five supertetrahedral T3-InSnS clusters is for the first time observed in the family of open-framework metal chalcogenides. Such secondary building units finally assemble into a rare NAB topological framework with large external space. In addition, the title semiconductor material also displays good properties in photocurrent response and electrocatalytic oxygen reduction reaction.

A 36-Membered Ring Metal Chalcogenide with a Very Low Framework Density

Reported here is a new open-framework metal chalcogenide containing extra-large 36-ring channels. This compound has a 3-connected etc topology by regarding supertetrahedral T2 clusters as the structural nodes. It has a very low framework density (3.4 tetrahedra per 1000 Å3) with each framework cation participating in three 3-rings. The organic cations within its intersecting channels can be partially exchanged out by Cs+ ions with the preservation of its framework structure.

Monodisperse Ultrasmall Manganese-Doped Multimetallic Oxysulfide Nanoparticles as Highly Efficient Oxygen Reduction Electrocatalyst

The highly efficient and cheap non-Pt-based electrocatalysts such as transition-based catalysts prepared via facile methods for oxygen reduction reaction (ORR) are desirable for large-scale practical industry applications in energy conversion and storage systems. Herein, we report a straightforward top-down synthesis of monodisperse ultrasmall manganese-doped multimetallic (ZnGe) oxysulfide nanoparticles (NPs) as an efficient ORR electrocatalyst by simple ultrasonic treatment of the Mn-doped Zn-Ge-S chalcogenidometalate crystal precursors in H2O/EtOH for only 1 h at room temperature. Thus obtained ultrasmall monodisperse Mn-doped oxysulfide NPs with ultralow Mn loading level (3.92 wt %) not only exhibit comparable onset and half-wave potential (0.92 and 0.86 V vs reversible hydrogen electrode, respectively) to the commercial 20 wt % Pt/C but also exceptionally high metal mass activity (189 mA/mg at 0.8 V) and good methanol tolerance. A combination of transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and electrochemical analysis demonstrated that the homogenous distribution of a large amount of Mn(III) on the surface of NPs mainly accounts for the high ORR activity. We believe that this simple synthesis of Mn-doped multimetallic (ZnGe) oxysulfide NPs derived from chalcogenidometalates will open a new route to explore the utilization of discrete-cluster-based chalcogenidometalates as novel non-Pt electrocatalysts for energy applications and provide a facile way to realize the effective reduction of the amount of catalyst while keeping desired catalytic performances.