Search

The dominance of plastics in the packaging market is due to their low weight and thickness, which save transportation costs. However, their non-biodegradability poses a significant threat to the environment. Paper, on the other hand, is considered as a safer alternative due to its natural composition and biodegradability. The porous structure of paper limits its application in packaging, and its poor water resistance further restricts its use in humid environments. Therefore, lamination is a method useful tool to improve the barrier properties of paper. Additionally, the researchers are focusing on developing biodegradable and water-based coatings with anti-fat properties as a green alternative to plastic packaging. The impact of a new grease-resistant coating composed of starch, gelatin and sodium alginate on the mechanical properties of paper was investigated through tensile, tearing, and bursting strength tests. The results showed significant improvements in the mechanical properties of the coated paper sheets. Furthermore, the biodegradability test indicated that the paper samples coated with the new composition showed a 50% weight loss after one week of incubation in the soil, and after three weeks, they exhibited 100% weight loss, demonstrating their outstanding biodegradability.

Developing robust electrocatalysts based on nonprecious metals with high activity in the sluggish oxygen-evolution reaction (OER) is crucial for achieving large-scale hydrogen production. We present a novel approach to design a molecular iron-based hybrid composed of Fe3O4, Fe, and FeNi3 with a sphere-like structure deposited on a flaky substrate. Our optimized catalyst, denoted as Fe/Ni_450C, demonstrates superior electroactivity with a low overpotential of 307 mV, and a minimal Tafel slope of 42 mV dec−1. The material demonstrates ultra-high durability in a 425 h stability test, retaining 86.80% of initial potential at 10 mA cm−2, and exhibits outstanding resistance to high currents (450 mA). The ex situ XRD, XPS, and Mössbauer spectroscopy analyses shed light on the underlying mechanism. Utilizing low-temperature operational conditions, environmentally friendly substrates, cost-effectiveness, high abundance, and impressive stability at high current density collectively position our findings as a pivotal step toward practical applications in the industry associated with electrochemical water decomposition. [ABSTRACT FROM AUTHOR]

Recently, water oxidation or oxygen evolution reaction (OER) in electrocatalysis has attracted huge attention due to its prime role in water splitting, rechargeable metal–air batteries, and fuel cells. Here, we demonstrate a facile and scalable fabrication method of a rod-like structure composed of molybdenum disulfide and carbon (MoS2/C) from parent 2D MoS2. This novel composite, induced via the chemical vapor deposition (CVD) process, exhibits superior oxygen evolution performance (overpotential = 132 mV at 10 mA cm−2 and Tafel slope = 55.6 mV dec−1) in an alkaline medium. Additionally, stability tests of the obtained structures at 10 mA cm−2 during 10 h followed by 20 mA cm−2 during 5 h and 50 mA cm−2 during 2.5 h have been performed and clearly prove that MoS2/C can be successfully used as robust noble-metal-free electrocatalysts. The promoted activity of the rods is ascribed to the abundance of active surface (ECSA) of the catalyst induced due to the curvature effect during the reshaping of the composite from 2D precursor (MoS2) in the CVD process. Moreover, the presence of Fe species contributes to the observed excellent OER performance. FeOOH, Fe2O3, and Fe3O4 are known to possess favorable electrocatalytic properties, including high catalytic activity and stability, which facilitate the electrocatalytic reaction. Additionally, Fe-based species like Fe7C3 and FeMo2S5 offer synergistic effects with MoS2, leading to improved catalytic activity and durability due to their unique electronic structure and surface properties. Additionally, turnover frequency (TOF) (58 1/s at the current density of 10 mA cm−2), as a direct indicator of intrinsic activity, indicates the efficiency of this catalyst in OER. Based on ex situ analyzes (XPS, XRD, Raman) of the electrocatalyst the possible reaction mechanism is explored and discussed in great detail showing that MoS2, carbon, and iron oxide are the main active species of the reaction. [ABSTRACT FROM AUTHOR]

Developing a robust and highly efficient electrocatalyst for the oxygen evolution reaction (OER) is required, due to its sluggish mechanism and high overpotential. Here, we present the Ti 3 C 2 T x and ZIF-67 composites (MXene/ZIF-67) for an efficient OER. The MXene/ZIF-67_1:10 exhibits an overpotential of 366 mV, which is better than MXene (548 mV) and RuO 2 (395 mV). Moreover, it shows improved electrochemical stability at 20 mA·cm− 2 with only a 0.2% increase in potential after 5 h, while RuO 2 with an overpotential loss of 3.5%. After an increase in the current density of 10–20 mA cm−2 the potential increase by 7.4%, while in RuO 2 by 25.3%. To reveal the observed performance, the composite's robustness and explain each component's role. Moreover, a detailed OER mechanism is discussed. It was realized via in situ Raman microscopy and XRD which allowed the revealing of the active species responsible for boosting OER. • MXene/ZIF-67 composite was designed for OER. • MXene/ZIF-67 presented outstanding electrocatalytic activity in OER. • MXene/ZIF-67 structures exhibit robust stability at high current density for a long time. • In situ Raman and XRD were applied to revile the mechanism of OER. [ABSTRACT FROM AUTHOR]

The potential of nitrogen‐doped carbon nanofibers with encapsulated Ni nanoparticles as a bifunctional catalyst in H2 and O2 evolution reactions (HER and OER, respectively) was studied. The proposed heterostructure is fabricated via a facile chemical vapor deposition on Ni supported on graphitic carbon nitride (GCN) as a precursor. HER was an effect of photocatalytic water splitting and catalytic dehydrogenation of lactic acid used as sacrificial electron donor. However, photocatalysis played the dominant role in the acceleration of the reaction rate which was 17 times and 330 times higher in respect to the sample prior the CVD and to pristine GCN, respectively. The catalyst exhibited boosted electrocatalytic activity in OER and outstanding stability in respect to RuO2 in alkaline medium. The overpotentials calculated from linear sweep voltammetry at 10 mA cm−2 is ∼383 mV for the fabricated electrocatalyst in respect to 490 mV for the RuO2 and Tafel slope is calculated to be 106 mV dec−1 in comparison to 136 mV dec−1 for the reference which is above the state‐of the‐art bifunctional catalysts reported to date. The results reveal that the catalytic processes were boosted due to several key effects such as enhanced visible light absorption, better charge carriers transfer and separation, increased free charge carrier concentration and higher reducing ability of electrons. [ABSTRACT FROM AUTHOR]

This study reveals a simple approach to recycle wasted coffee grounds into highly valuable carbon material with superior electrochemical performance. Activated carbon prepared from wasted coffee grounds has been formed via hydrothermal acidic hydrolysis followed by a KOH chemical activation at 800 ∘ C . To understand the electrochemical properties of the sample, a set of characterization tools has been utilized: N2 and CO2 adsorption–desorption isotherms, thermal gravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy and scanning electron microscopy. The specific surface area obtained from a Brunner–Emmett–Teller (BET) analysis reached 2906 ± 19 m 2 g − 1 . Prepared sample (designated as ACG-800KOH) was tested as electrode material in an electric double layer capacitor (EDLC) device with ionic liquid PYR13-TFSI as an electrolyte. The EDLC test was conducted at temperatures ranging from 20 to 120 ∘ C . The specific material capacitance reached 178 F g − 1 measured at 20 ∘ C and 50 A g − 1 and was in the range 182 to 285 F g − 1 at the 20 to 120 ∘ C temperature range. [ABSTRACT FROM AUTHOR]

The renewable energy technologies require electrocatalysts for reactions, such as the oxygen and/or hydrogen evolution reaction (OER/HER). They are complex electrochemical reactions that take place through the direct transfer of electrons. However, mostly they have high over-potentials and slow kinetics, that is why they require electrocatalysts to lower the over-potential of the reactions and enhance the reaction rate. The commercially used catalysts (e.g., ruthenium nanoparticles—Ru, iridium nanoparticles—Ir, and their oxides: RuO2, IrO2, platinum—Pt) contain metals that have poor stability, and are not economically worthwhile for widespread application. Here, we propose the spinel structure of nickel-cobalt oxide (NiCo2O4) fabricated to serve as electrocatalyst for OER. These structures were obtained by a facile two-step method: (1) One-pot solvothermal reaction and subsequently (2) pyrolysis or carbonization, respectively. This material exhibits novel rod-like morphology formed by tiny spheres. The presence of transition metal particles such as Co and Ni due to their conductivity and electron configurations provides a great number of active sites, which brings superior electrochemical performance in oxygen evolution and good stability in long-term tests. Therefore, it is believed that we propose interesting low-cost material that can act as a super stable catalyst in OER. [ABSTRACT FROM AUTHOR]

In this study, the catalytic performance of Ti 3 C 2 MXene materials in the reaction of α-pinene isomerization was demonstrated. The influence of etching agents (HF, HF/H 2 SO 4, and HF/HCl; weight ratios of mixed acids: 1 : 3, 1 : 4, and 1 : 5) on removing Al atoms from MAX phase, creation of an accordion-like structure typical for MXenes and catalytic activity of the produced samples have been revealed. The MXene HF obtained by MAX phase HF treatment exhibited the highest activity (conversion of α-pinene 74.65 mol%), while materials produced with the mixed acids (HF/H 2 SO 4 and HF/HCl) showed a significant reduction in the conversion of α-pinene (on average about 28-fold). However, these last samples displayed an increase of about 10 mol% in the selectivity to the most desirable product-camphene. The high activity of MXene HF is a result of a high concentration of acid sites (11.62 mmol g -1 ) - the concentration of acid sites in the samples obtained by MAX phase mixed acids treatment was about 2.5-5.5 times smaller. This work proposes possible mechanisms for the α-pinene isomerization reaction on the MXene HF and on the MXene HF/H 2 SO 4 X  :  Y and MXene HF/HCl X  :  Y in connection with their structure., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)