Formulation of Nano/Micro-Carriers Loaded with an Enriched Extract of Coffee Silverskin: Physicochemical Properties, In Vitro Release Mechanism and In Silico Molecular Modeling

Designing strategies for an effective transformation of food waste into high-value products is a priority to address environmental sustainability concerns. Coffee silverskin is the major by-product of the coffee roasting industry, being rich in compounds with health benefits. Such composition gives it the potential to be transformed into high-value products. In this study, coffee silverskin extracts were enriched, regarding caffeine and chlorogenic acid contents, by adsorbent column chromatography. The compounds content increased 3.08- and 2.75-fold, respectively, compared to the original extract. The enriched fractions were loaded into nano-phytosomes or cholesterol-incorporated nano-phytosomes (first coating layers) to improve the physiochemical properties and permeation rate. These nano-lipid carriers were also subjected to a secondary coating with different natural polymers to improve protection and stability against degradation. In parallel, and for comparison, different natural polymers were also used as first coating layers. The produced particles were evaluated regarding product yield, encapsulation efficiency, loading capacity, particle size, surface charge, and in vitro release simulating gastrointestinal conditions. All samples exhibited anionic surface charge. FTIR and molecular docking confirmed interactions between the phytoconstituents and lipid bilayers. The best docking score was observed for 5-caffeoylquinic acid (chlorogenic acid) exhibiting a stronger hydrogen binding to the lipid bilayer. Among several kinetic models tested, the particle release mechanism fitted well with the First-order, Korsmeyer–Peppas, and Higuchi models. Moreover, most of the formulated particles followed the diffusion-Fick law and anomalous transport.

Examination of the Brønsted−Evans−Polanyi Relationship for the Hydrogen Evolution Reaction on Transition Metals Based on Constant Electrode Potential Density Functional Theory

In the search for efficient and inexpensive electrocatalysts for the hydrogen evolution reaction (HER), the hydrogen binding energy (ΔG*H) is often used as a descriptor to represent the catalytic activity....

Enhancement of hydrogen evolution reaction kinetics in alkaline media by fast galvanic displacement of nickel with rhodium – from smooth surfaces to electrodeposited nickel foams

Energy-efficient hydrogen production is one of the key factors for advancing the hydrogen-based economy. Alkaline water electrolysis is the main route for the production of high-purity hydrogen, but further improvements of hydrogen evolution reaction (HER) catalysts are still needed. Industrial alkaline electrolysis relies on Ni-based catalysts, and here we describe a drastic improvement of HER activity of Ni in alkaline media using several model catalysts for HER obtained upon nickel surface modification in aqueous solution of rhodium salts, when a spontaneous deposition of rhodium takes place based on the chemical displacement reaction 3Ni + 2Rh3+ = 3Ni2+ + 2Rh. In the case of smooth Ni-poly electrodes, HER activity surpasses the activity of Pt-poly already after 30 s of exchange with Rh. SEM analysis showed that Rh is uniformly distributed, while surface roughness changes within 10%, agreeing with electrochemical measurements. Furthermore, XPS analysis has shown effective incorporation of Rh in the surface, while DFT calculations suggest that hydrogen binding is significantly weakened on the Rh-modified Ni surfaces. Such tuning of the hydrogen binding energy is seen as the main factor governing HER activity improvements. The same galvanic displacement protocols were employed for nickel foam electrodes and electrodeposited Ni on Ti mesh. In both cases, somewhat longer Rh exchange times are needed to obtain superior activities than for the smooth Ni surface, but up to 10 min. HER overpotential corresponding to −10 mA cm−2 for nickel foam and electrodeposited Ni electrodes, after modification with Rh, amounted to only −0.07 and −0.09 V, respectively. Thus, it is suggested that a fast spontaneous displacement of Ni with Rh could effectively boost HER in alkaline media with minor cost penalties compared to energy saving in the electrolysis process.

Computational Study of Hydrogen Molecules Adsorption on Boron Nitride with/without Adopted by One of Elements from Group IV

In this study, we reported the adsorption of two hydrogen (H2) molecules on six boron nitride (BN) studied models with or without adopted by one of the elements from Group IV. By employing the computational method of density functional theory (DFT), the hydrogen binding energies and electronic structures were analyzed and discussed. The computed results presented that the most favorable adsorption sites were found for the two H2 molecules in all studied systems. The computed optimal binding energies of all BN studied systems were determined to be 0.01 eV – 0.05 eV per H2 molecule, which is smaller than that of the previous literature study. Moreover, the energies of HOMO–LUMOs were predicted in the range of 1.64 eV – 6.18 eV. For the surface plots of molecular electrostatic potentials (MEPs), the H atoms at the N–edges possess the most positive electrostatic potentials, while the negative electrostatic potentials fall in the atoms of H at the B–edges. A similar trend was presented on the distribution of atomic charge. Using the scheme of Mulliken population analysis (MPA), there are two different charge values on the atom of H in this study. The H atoms at the B–edges possess the negative charges, whereas the positive charge values were found on the atoms of H at the N–edges. In addition, the findings also noted that the positive charge values were presented for all B atoms in the study. While the negative charges fall in the atoms of N.