The magic reducible oxides properties likely are mainly due to the presence of oxygen defects and their rich surface chemistry, which provide a rational pathway to the emergent of entirely new properties. Although significant progress has performed in the last years, it can be stated that they are not fully understood at the nanoscale level so far. This mini-review provides a comprehensive perspective on the oxygen defects and surface chemistry of reducible oxides based on materials with two-dimensional (2D) structure. Thus, in this perspective, we intend to discuss some of the main challenges and opportunities in this important field of research in materials chemistry and engineering. From a practical standpoint, chemical insights from defect-engineering may provide vital clues for improving synthetic methods and understanding fundamental nanoscale properties, driving innovation in the field of reducible oxides based on 2D structure materials.

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The production, characterization and application of activated carbon obtained from corncobs as an adsorbent was studied. Fresh material was submitted to thermal analysis (TG-DTA), and the carbon obtained from chemical activation was characterized by specific surface area (S BET), distribution of pore size (DFT), Scanning Electron Microscopy (SEM) and Infrared spectroscopy with Fourier transform (FT-IR). The adsorption of orange dye (OG) and methylene blue (MB) proved that data from isothermal adsorption were better adjusted to the Sips model. The maximum quantities, 86 mg g-1 and 124 mg g-1 , were obtained respectively for the adsorption of the dyes Orange G (OG) and Methylene Blue (MB). The results allow to conclude that the chemical activation of corncobs was responsible for the production of material, which is adequate to be applied as an adsorbent, enabling reuse of this agroindustrial residue.

Ni-CeO 2 nanorods catalysts (1-10 wt% Ni loadings) were evaluated in steam reforming of ethanol (SRE). Ex situ and in situ characterization showed two populations of Ni species according to Ni loading: (i) one highly dispersed, strongly interacting with CeO 2 (Ni sup ) and (ii) another one formed by Ni nanoparticles (Ni bulk ). While the metal loading impacted on the Ni bulk fraction, the Ni sup population remained similar, leading to similar activities of the catalysts toward SRE. The results highlight the role of the Ni sup fraction in the catalyst performance. Nevertheless, we found that while Ni bulk species favored carbon deposition, the Ni sup species were easily oxidized at low temperatures, leading to catalyst deactivation. The results suggest that the co-existence of both Ni species may stabilize the reduced form of the Ni sup species by hydrogen activation on the Ni bulk species and represents a new strategy to be explored to optimize the activity and stability of SRE catalysts.