This article reviews the current state and development of thermal catalytic processes using transition metals (TM) supported on zeolites (TM/Z), as well as the contribution of theoretical studies to understand the details of the catalytic processes. Structural features inherent to zeolites, and their corresponding properties such as ion exchange capacity, stable and very regular microporosity, the ability to create additional mesoporosity, as well as the potential chemical modification of their properties by isomorphic substitution of tetrahedral atoms in the crystal framework, make them unique catalyst carriers. New methods that modify zeolites, including sequential ion exchange, multiple isomorphic substitution, and the creation of hierarchically porous structures both during synthesis and in subsequent stages of post-synthetic processing, continue to be discovered. TM/Z catalysts can be applied to new processes such as CO₂ capture/conversion, methane activation/conversion, selective catalytic NO_x reduction (SCR-deNO_x), catalytic depolymerization, biomass conversion and H₂ production/storage.

Mono- and bimetallic systems of Ag, Fe, and Ag–Fe exchanged in sodium mordenite zeolite were studied in the reaction of NO reduction. The transition metal cations Ag and Fe were introduced by ion exchange method both at room temperature and 60 °C; modifying the order of component deposition in bimetallic systems. These materials were characterized by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), ultraviolet-visible spectroscopy (UV-Vis), X-Ray photoelectron Spectroscopy (XPS) and High-resolution transmission electron microscopy (HR-TEM). The XPS and UV–Vis spectra of bimetallic samples revealed that under certain preparation conditions Ag⁺ is reduced with the participation of the Fe²⁺/Fe³⁺ ions transition and is present in the form of a Ag reduced state in different proportions of Ag_m clusters and Ag⁰ NPs, influenced by the cation deposition order. The catalytic results in the NO reduction reaction using C₃H₆/CO under an oxidizing atmosphere show also that the order of exchange of Ag and Fe cations in mordenite has a strong effect on catalytic active sites for the reduction of NO.

The limited access to fresh water and the increased presence of emergent pollutants (EPs) in wastewater has increased the interest in developing strategies for wastewater remediation, including photocatalysis. Graphitic carbon nitride (g-C₃N₄) is a 2D non-metal material with outstanding properties, such as a 2.7 eV bandgap and physicochemical stability, making it a promising photocatalyst. This work reports the process of obtaining high-surface-area (SA) g-C₃N₄ using the thermal-exfoliation process and the posterior effect of Ag-nanoparticle loading over the exfoliated g-C₃N₄ surface. The photocatalytic activity of samples was evaluated through methylene blue (MB) degradation under visible-light radiation and correlated to its physical properties obtained by XRD, TEM, BET, and UV–Vis analyses. Moreover, 74% MB degradation was achieved by exfoliated g-C₃N₄ compared to its bulk counterpart (55%) in 180 min. Moreover, better photocatalytic performances (94% MB remotion) were registered at low Ag loading, with 5 wt.% as the optimal value. Such an improvement is attributed to the synergetic effect produced by a higher SA and the role of Ag nanoparticles in preventing charge-recombination processes. Based on the results, this work provides a simple and efficient methodology to obtain Ag/g-C₃N₄ photocatalysts with enhanced photocatalytic performance that is adequate for water remediation under sunlight conditions.

Composites of Ag and TiO₂ nanoparticles were synthesized in situ on cotton fabrics using sonochemical and solvothermal methods achieving the successive formation of Ag-NPs and Ti-NPs directly on the fabric. The impregnated fabrics were characterized using ATR-FTIR spectroscopy; high-resolution microscopy (HREM); scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS); Raman, photoluminescence, UV-Vis, and DRS spectroscopies; and by tensile tension tests. Results showed the successful formation and impregnation of NPs on the cotton fabric, with negligible leaching of NPs after several washing cycles. The photocatalytic activity of supported NPs was assessed by the degradation of methyl blue dye (MB) under solar and UV irradiation revealing improved photocatalytic activity of the Ag–TiO₂/cotton composites due to a synergy of both Ag and TiO₂ nanoparticles. This behavior is attributed to a diminished electron–hole recombination effect in the Ag–TiO₂/cotton samples. The biocide activity of these composites on the growth inhibition of Staphylococcus aureus (Gram+) and Escherichia coli (Gram−) was confirmed, revealing interesting possibilities for the utilization of the functionalized cotton fabric as protective cloth for medical applications.