Rhodamine interlayer reduces trap states at the PCBM surface while hindering moisture access.

In this study, a carbonaceous material was obtained from the thermal decomposition of a non-pretreated rice husk in a pyrolysis system with controlled nitrogen at 700, 800, 900, and 1000 °C. The characterization of the material was performed using various analytical techniques. The results of these characterizations indicate that the obtained carbonaceous material can achieve a surface area of 450 m²/g, with a microporous volume of 0.15 cm³/g. Furthermore, the presence of oxygenated function groups, predominantly hydroxyl (C-OH) and epoxy (C-O-C), along with amorphous silicon, was identified. Additionally, the material’s CO₂ adsorption capacity was assessed, revealing a maximum capacity of 1.0 mmol/g. The findings of this study suggest that the CO₂ adsorption effectiveness can be impacted by the presence of specific functional groups. These groups have been shown to enhance the material’s affinity for CO₂, along with its porosity and surface area. In this sense, a notable correlation was identified between the oxygenated function group content and CO₂ adsorption capacity. Also, the adsorption isotherm modeling showed an excellent fit to the Langmuir model, indicating monolayer adsorption on a homogeneous surface.

We describe and illustrate Dracula colombiana sp. nov. a new orchid species from the eastern Andes of Colombia, previously misidentified as D. benedictii in herbaria, private collections, and commercial trade. The new species resembles D. benedictii but can be distinguished by its solid pink lip with an ovate, glabrous epichile longer than the hypochile (vs. white, suborbicular epichile shorter than the hypochile) and sepals with brown-red papillae and pubescence (vs. purple black, verrucose sepals). Based on IUCN Red List criteria, we propose that the species be classified as Endangered (EN) under sub-criterion B2a, due to its restricted geographic distribution and the threats posed by potentially unsustainable harvesting. Conservation measures are urgently needed to protect natural populations, regulate its presence in the orchid trade, and address taxonomic misidentifications in global markets.

Introduction: the agroindustry generates significant waste, posing environmental, health, and economic challenges. Among these, rice husk, a byproduct of the food industry, stands out due to its potential as a source of silicon. Due to its silicon content, rice husk offers a unique opportunity for sustainable energy production and the extraction of high-value products, such as amorphous silicon dioxide (SiO2). However, optimizing processes for its efficient conversion remains a challenge.Objective: the aim of this study was to optimize the nitric acid concentration for the pretreatment of Colombian rice husk in order to produce high-purity amorphous SiO2 and demonstrate the feasibility of scaling up the process.Methods: a two-stage process was developed, which involved treating rice husk with nitric acid, followed by calcination at 620 °C. The nitric acid concentration was optimized to achieve the highest SiO2 purity. Material characterization was performed using thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray fluorescence (XRF), and nitrogen adsorption-desorption. To assess the scalability of the process, the treatment was replicated on a larger scale using the optimized acid concentration.Results: the optimized process using a nitric acid concentration of 0.2 M yielded amorphous SiO2 with a purity of 94.9% and a surface area of 298 m²/g. When scaled up, the process achieved SiO2 with a purity of 95.5%, confirming the feasibility of the methodology for industrial applications. Conclusions: the treatment of rice husk with nitric acid followed by calcination proves to be an effective and scalable approach for producing high-purity amorphous SiO2. This process not only holds potential for industrial applications but also provides a sustainable solution for valorizing agroindustrial waste, contributing to the circular economy.

In this paper zeolite Beta was synthesized and characterized by XRD, ATG, ATD, XRF and SEM. Subsequently various modifications were made using a surface passivation process in liquid phase with tetraethylorthosilicate (TEOS), using two loads of TEOS and three passivation cycles, in order to obtain six catalysts. These materials were characterized by NH3-TPD and tested in tolune disproportionation reaction, under different conditions of pressure and temperature. As modification cycles were increased for each catalyst, there was a change in the acidity of the solids, mainly due to deposition of an inert layer of silica on the external surface. These results were confirmed with the improvement in para-selectivity and decreasing in conversion. Despite zeolite Beta is a large pore zeolite, an improvement of the para-selectivity was obtained, achieving almost stable values for the entire range of temperature and pressure conditions.

Introduction: Carbon-based materials derived from agricultural waste, such as rice husk (RH), have attracted increasing attention due to their potential for sustainable applications, particularly in electronics, environmental sensing, and energy storage.Objectives: This study aims to investigate the synthesis of carbon materials from RH through thermal decomposition at two different temperatures (900 °C and 1000 °C), and to evaluate their application in humidity sensor fabrication, focusing on the influence of carbonization temperature on their structural and functional properties.Materials and Methods: Carbon materials were synthesized from RH via pyrolysis at 900 °C and 1000 °C. Their structural properties and degree of graphitization were characterized using X-ray diffraction (XRD) and Raman spectroscopy. The resulting materials were then incorporated into conductive inks using different binders and solvents to fabricate resistive humidity sensors. The electrical response of the sensors was evaluated under controlled relative humidity conditions.Results: Structural analyses revealed that higher carbonization temperatures led to more crystalline structures and enhanced graphitization. The fabricated sensors exhibited varying electrical responses depending on the pyrolysis temperature, showing different resistance-relative humidity relationships.Conclusions: Carbonization temperature significantly affects the structural and functional properties of RH-derived carbon materials. These findings highlight the potential of optimizing such materials for environmental sensing applications, particularly humidity monitoring, contributing to the development of sustainable solutions in flexible and printed electronics.