The development of sorbents for next-generation CO(2) mitigation technologies will require better understanding of CO(2)/sorbent interactions. Among the sorbents under consideration are shape-selective microporous molecular sieves with hierarchical pore morphologies of reduced dimensionality. We have characterized the non-equilibrium CO(2) sorption of OMS-2, a well-known one-dimensional microporous octahedral molecular sieve with manganese oxide framework. Remarkably, we find that the degree of CO(2) sorption hysteresis increases when the gas/sorbent system is allowed to equilibrate for longer times at each pressure step. Density functional theory calculations indicate a "gate-keeping" role of the cation in the tunnel, only allowing CO(2) molecules to enter fully into the tunnel via a highly unstable transient state when CO(2) loadings exceed 0.75 mmol/g. The energy barrier associated with the gate-keeping effect suggests an adsorption mechanism in which kinetic trapping of CO(2) is responsible for the observed hysteretic behavior.

A continuous flow microwave method has been developed for the synthesis of cryptomelane-type K-OMS-2 nanomaterials in a mixed aqueous−organic solvent system. The system is ideal for multikilogram synthesis of K-OMS-2 nanomaterials. The synthesized nanomaterials have crystallite sizes of about 1.8 nm with a surface area of 213 m2/g. X-ray diffraction (XRD), electron microscopy (SEM and TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), nitrogen sorption experiments, and potentiometric titrations have been used to characterize the nanomaterials. Kinetically, an increase in power has a direct relation to increase in temperature, and this has an effect on reaction rate. The synthesized materials show excellent results in the oxidation of 2,3,6-trimethylphenol.

A tunable shape microwave synthesis of ZnO nanospheres in a cosolvent mixture is presented. The ZnO nanospheres material is investigated as a desulfurizing sorbent in a fixed bed reactor in the temperature range 200−400 °C and compared with ZnO nanorod and platelet-like morphologies. Fresh and sulfided materials were characterized by X-ray diffraction, BET specific surface area, pore volume, scanning electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy, and thermogravimetric analysis. The tunable shape microwave synthesis of ZnO presents a high sulfur sorption capacity at temperatures as low as 200 °C, which accounts for three and four times the other preparations presented in this work, and reached 76% of the theoretical sulfur capacityat 300 °C.

Cryptomelane-type manganese oxide (OMS-2) has been widely used to explore the semiconducting and catalytic properties of molecular sieves with mixed-valent frameworks. Selective synthesis of patterned thin films of OMS-2 with hierarchical nanostructures and oriented crystals is challenging owing to difficulties in preserving the mixed valence, porosity and crystalline phase. Here, we report that pulsed-laser ablation of OMS-2 in an oxygen-rich medium produces a three-dimensional nanostructured array of parallel and inclined OMS-2 fibres on bare substrates of (001) single-crystal strontium titanate. Both parallel and inclined OMS-2 fibres elongate along the [001](OMS-2) direction. The parallel fibres interact strongly with the substrate and grow epitaxially along <110>(STO) with lattice misfits of less than 4%, whereas the inclined fibres are oriented with (301) parallel to the substrate surface. The spontaneous orientation of the crystalline OMS-2 domains over the STO surface opens up a new avenue in lattice-engineered synthesis of multilayer materials.

Multicomponent metal oxide (MMO) crystallites are prepared by spraying a reactant solution into a receiving solution or into air under microwave radiation at atmospheric pressure. The injection of a nitric acid solution through an ultrasonic nozzle into a receiving solution of metal precursor and the use of microwave radiation are combined to form a novel preparation technique called the nozzle‐spray/microwave (NMW) method. The inclusion of an additional step, the in situ mixing of precursor solutions prior to their injection through the ultrasonic nozzle spray, leads to another procedure called the in situ/nozzle‐spray/microwave (INM) method. For comparison, MMO materials with the same metal constituents as those prepared by our novel techniques are prepared by conventional hydrothermal (CH) methods. Fresh materials prepared by NMW, INM, and CH methods were heat treated to study the effect of calcination. All materials were characterized before and after calcination using X‐ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller surface area, and inductively coupled plasma elemental analysis. The NMW method produces particles with rodlike morphologies different from those obtained using CH methods. The INM method produces an amorphous material that crystallizes after calcination into small (ca. 200 nm) particles with interesting morphologies. Notably, calcination of materials prepared by both NMW and INM reduces the particle size and increases the surface area. The work presented in this paper paves the way to use NMW and INM to prepare MMOs with unique morphologies.