Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), the two concurrent reactions for the electrolytic production of green H₂, require low-cost and sustainable electrocatalysts for their scale-up, as for example non-noble metals and carbonaceous structures with high surface area. Our hypothesis is that the activated-doped biochar decorated with Mo and Co provides high porosity and active site dispersion, enhancing HER and OER kinetics with low overpotentials and high stability in an alkaline medium. Here, a bifunctional Mo/Co electrocatalyst supported on N-doped biochar obtained from hazelnut shells has been developed, thus valorizing an agro-industrial residue of major importance in Chile. The activated biochar matrix, with interconnected hierarchical pores, offered a high surface area of 1102 m² g⁻¹ and I_D/I_G = 1.08 graphitization, while N-doping was observed by XPS, with the formation of N-pyridinic and N-graphitic functionalities that improved the catalytic performance. The addition of metals to the substrate allowed the formation of bimetallic Mo/Co active sites (Co₆Mo₆C), increasing the graphitization degree and improved the growth of these bimetallic sites. The electrocatalytic performance in the presence of the metals was good, revealing low overpotentials for HER (0.257 V) and OER (0.370 V) with low Tafel slopes (51 and 59 mV dec⁻¹, respectively) under alkaline conditions, also improving the electron transfer and stability. Graphical Abstract

Castor bean is found in Chile between the Arica and Parinacota and Maule regions and is one the most important industrial crops worldwide because of the presence of ricinoleic acid in its oil. However, there is little information about it in our country. In this study, we analyzed the oil content and fatty acid profiles of 17 castor bean Chilean accessions from the Metropolitana and Valparaíso regions. The seed-oil was extracted using the Soxhlet extraction process, and the fatty acid profiles were determined using the GC-FID method. The oil content in castor bean Chilean accessions ranged between 45.7% and 54.0%. Among the 17 accessions analyzed, H-15 had the highest oil content (54.0%; p < 0.05), whereas the H-10 and H-08 accessions had the lowest oil content, (45.7% and 45.9%, respectively; p < 0.05). Ricinoleic acid was the most abundant fatty acid (between 87.64% and 89.83%) in the seed-oil. The highest level of ricinoleic acid was found in the H-08 accession. This was only statistically higher (p < 0.05) for three accessions, whereas the H-04 accession had the lowest ricinoleic acid content. Although the H-08 accession registered one of the least abundant oil contents, it had the highest amount of ricinoleic acid. No significant correlation was found between oil content and ricinoleic acid. Our study suggests that oil content does not influence the castor oil fatty profile. The high oil content and ricinoleic acid level registered in castor bean Chilean accessions justify their production in Chile and their utilization for developing bio-based products. Furthermore, Chilean castor bean could grow in semi-arid lands. However, further field studies are needed to identify the cultivars best suited for Mediterranean conditions.

The purpose of this study was to verify the feasibility of using biochar from oat hulls (BO) as a potential bio-modifier to improve the physical properties of conventional asphalt binder. The BO and asphalt binder were characterized by confocal (fluorescence) laser microscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. Then, an asphalt binder modification procedure was established and modifications with 2.5, 5.0 and 7.5% of BO on the weight of the asphalt binder were evaluated, using a particle size < 75 µm. The physical properties of the evaluated modified asphalt binder with BO were: rotational viscosity in original and aged state, aging index, Fraass breaking point, softening point, penetration, penetration rate and storage stability. The results indicated that the BO has a porous structure, able to interact with the asphalt binder by C=O and C=C bonds. In addition, modification of the asphalt binder with BO increases the rotational viscosity related to high-temperature rutting resistance. The results obtained from the Fraass breaking point and softening point indicated that the use of BO extends the viscoelastic range of the asphalt binder. In addition, the evaluated modifications present low susceptibility to aging and good storage stability.

In this study, the effect of biochar from oat hulls (BO) on the rheological properties of a PG 64-22 asphalt binder was evaluated using a full factorial design, which included the following factors: pyrolysis temperature (PT) (300 °C and 500 °C), BO particle size (<20 µm and <75 µm), and the amount of BO (2.5%, 5%, and 7.5%). First, the morphological and physicochemical properties of BO were analyzed by comparing it with graphite powder (CFG) and commercial activated carbon (CAC). The physicochemical properties of the modified asphalt binder were then evaluated using confocal laser microscopy, scanning electron microscopy (SEM–EDX), and Fourier-transform infrared spectroscopy (FTIR). Its storage stability was also evaluated. Subsequently, the rutting parameter G*/sin(δ) and the Fraass breaking point were analyzed to select asphalt binders that extended their viscoelastic range. The asphalt binders selected were those with 2.5%, 5%, and 7.5% BO, produced at a PT of 300 °C with a particle size <20 µm (BO300S). Next, the rheological properties of the selected samples were evaluated by testing for rotational viscosity, rutting parameter G*/sin(δ), multiple stress creep recovery (MSCR), fatigue parameter G*·sin(δ), and creep stiffness by bending beam rheometry (BBR). The rheological aging index according to rutting parameter G*/sin(δ) (RAI) was also evaluated. These tests were conducted in different states of the asphalt binder: original, short-term aged, and long-term aged. According to the results, the application of BO300S significantly increased the resistance of the asphalt binder to rutting and rotational viscosity, proportional to the amount added to the asphalt binder. Moreover, low modifier percentages improved fatigue resistance, outperforming CFG and CAC. In addition, it performs well at low service temperatures, registering better resistance than the control asphalt binders.