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Design of composite in form of ultrasmall loading of Ni2+dimers, with DFT modeled active centers, in ZIF-67 serves as general approach promoting electrocatalytic performance of oxygen evolution reaction which follows lattice oxygen mechanism

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.

Here, we report a general strategy for designing a metal/carbon system, via a facile and environmentally friendly one-step approach, from metal acetate as an active electrocatalyst in oxygen evolution reaction (OER) during water decomposition. As a demonstration, a nanostructured Ni/C composite induced from nickel acetate is revealed in great detail. The resulting material is composed of: metallic nickel (Ni), nickel(II) oxide (NiO), and nickel carbide (Ni3C) coated with a graphitic shell and deposited on a carbon platform. Our findings underscore the prominent role of nickel species, including Ni0, Ni2+, and Ni3+, in driving the catalytic activity. Notably, the catalyst exhibits an overpotential of 170 mV, a Tafel slope of 49 mV·dec−1, an electrocatalytic surface area (ECSA) of 964.7 cm2, and a turnover frequency (TOF) value of 52.8 s−1, surpassing RuO2. The Raman spectra also suggest a graphitic "self-healing" phenomenon post-OER, attributed to the reduction of oxygen-containing groups. Carbon in the system (i) facilitates electron transfer, (ii) allows homogeneous distribution of Ni nanoparticles avoiding their agglomeration, and (iii) promotes durability of the electrocatalyst by serving as a protective barrier, shielding the core metal compounds. What is more, density functional theory (DFT) calculations allowed to optimized geometry of the model cluster Ni8O8(OH)8describing two different sites on the β-NiOOH surface (001) and two different intermediates, (i)L-OOH and (ii)L-OOH. This facilitated to propose the reaction mechanisms involving both hydroxide ions and water molecules as reducers. Therefore, the chemisorption of OH−and H2O molecules at the NiOOH active center accompanied by bond breakage and the formation of a lattice hydroperoxide as an important intermediate is presumed. What is more, the proposed fabrication method for electroactive metal/carbon composites was validated with an iron and iron/nickel mixture.

Exploration of efficient, cost-effective, abundant, and environmentally friendly catalysts for generating clean and renewable energy resources is currently highly needed. Here, we designed a photocatalyst based on nickel oxide(II) nanoparticles embedded in a carbon matrix for the photocatalytic hydrogen evolution reaction (pHER). A super facile fabrication strategy involves using only one nontoxic substrate (nickel acetate) as a simultaneous source of nickel and carbon. The catalyst with tuned morphology (via process time) showed a superior pHER performance yielding 7.4 mmol/h, an effect of synergy between nickel nanoparticles and graphitic carbon. The synergy comes from (i) the conductive properties of carbon, (ii) defects present in the carbon matrix, which act as hydrogen evolution sites, and (iii) NiO nanoparticles, which improve charge carrier separation increasing the H2evolution rate. The mechanism of pHER was proposed based on an ex situstudy of the postprocessed catalyst with electron paramagnetic resonance spectroscopy (EPR), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). What is more, we propose a general and super simple approach to deliver carbon/metal oxide composites from different metal acetates to deliver catalytically active materials with tunable physicochemical properties that can meet the requirements of different processes.