CO₂ capture from industry sectors or directly from the atmosphere is drawing much attention on a global scale because of the drastic changes in the climate and ecosystem which pose a potential threat to human health and life on Earth. In the past decades, CO₂ capture technology relied on classical liquid amine scrubbing. Due to its high energy consumption and corrosive property, CO₂ capture using solid materials has recently come under the spotlight. A variety of porous solid materials were reported such as zeolites and metal-organic frameworks. However, amine-functionalized porous materials outperform all others in terms of CO₂ adsorption capacity and regeneration efficiency. This review provides a brief overview of CO₂ capture by various amines and mechanistic aspects for newcomers entering into this field. This review also covers a state-of-the-art regeneration method, visible/UV light-triggered CO₂ desorption at room temperature. In the last section, the current issues and future perspectives are summarized.

The doping of Au/TiO₂ with FeO_x is shown to result in a strong enhancement of its photocatalytic activity in the degradation of the azo dye Orange II. In order to examine the source of this enhancement, Au-FeO_x/TiO₂ nanocomposites containing different molar ratios of Au:Fe were synthesized, and X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), and high-resolution transmission electron microscope (HRTEM) analyses indicated that the TiO₂-supported Au nanoparticles were partially covered with an amorphous layer of FeO_x species, in which the iron was present as Fe²⁺ and Fe³⁺. The metal-semiconductor system, i.e., Au/TiO₂, showed only a moderate degradation rate, whereas doping with FeO_x strongly enhanced the degradation activity. The bandgap energy decreased gradually from Au/TiO₂ (3.13 eV) to the catalyst with the highest FeO_x loading Au-FeO_x (1:2)/TiO₂ (2.23 eV), and this decrease was accompanied by a steady increase in the degradation activity of the catalysts. XPS analyses revealed that compared to Au/TiO₂, on Au-FeO_x/TiO₂ a much higher population density of chemisorbed and/or dissociated oxygen species was generated, which together with the decreased bandgap resulted in the highest photocatalytic activity observed with Au-FeO_x (1:2)/TiO₂. The processes occurring during reaction on the catalyst surface and in the bulk liquid phase were investigated using operando attenuated total reflection IR spectroscopy (ATR-IR) combined with modulation excitation spectroscopy (MES), which showed that the doping of Au/TiO₂ with FeO_x weakens the interaction of the dye with the catalyst surface and strongly enhances the cleavage of the azo bond.

We present a systematic study on the support effect of metal–organic frameworks (MOFs), regarding substrate adsorption. A remarkable enhancement of both catalytic activity and selectivity for the ethanol (EtOH) production reaction through acetic acid (AcOH) hydrogenation (AH) was observed on Pt nanoparticles supported on MOFs. The systematic study on catalysis using homogeneously loaded Pt catalysts, in direct contact with seven different MOF supports (MIL-125-NH₂, UiO-66-NH₂, HKUST-1, MIL-101, Zn-MOF-74, Mg-MOF-74, and MIL-121) (abbreviated as Pt/MOFs), found that MOFs having a high affinity for the AcOH substrate (UiO-66-NH₂ and MIL-125-NH₂) showed high catalytic activity for AH. This is the first demonstration indicating that the adsorption ability of MOFs directly accelerates catalytic performance using the direct contact between the metal and the MOF. In addition, Pt/MIL-125-NH₂ showed a remarkably high EtOH yield (31% at 200 °C) in a fixed-bed flow reactor, which was higher by a factor of more than 8 over that observed for Pt/TiO₂, which was the best Pt-based catalyst for this reaction. Infrared spectroscopy and a theoretical study suggested that the MIL-125-NH₂ support plays an important role in high EtOH selectivity by suppressing the formation of the byproduct, ethyl acetate (AcOEt), due to its relatively weak adsorption behavior for EtOH rather than AcOH.