One-Step Spraying Strategy for Fabricating Bioinspired, Graphene-Based, and Multifunctional-Integrated Coatings on Structural Steel with Good Water Repellency, Fireproofing, Anticorrosion, and Durability.

Traditionally, many coatings were merely concentrated on settling the inherent fire protection problem of steel structures, while surface contamination and corrosion susceptibility should also be considered. Concurrently addressing these problems in fireproof efficiency and surface multifunctionality has become an issue of great significance in further expanding the application value in industrial and daily scenarios. Based on this condition, ecofriendly, graphene-based, and superhydrophobic coatings with multifunctional integration were constructed on steel via a one-step spraying method. The as-prepared coatings mainly consist of epoxy resin (EP), silicone resin (SR), a cyclodextrin-based flame retardant (MCDPM), expandable graphite (EG), and multilayered graphene (MG). The results demonstrate that the water contact angle (WCA) and water sliding angle (WSA) of as-prepared coatings can reach 156.8 ± 1.6 and 5.8 ± 0.7°, respectively, revealing good water repellency and self-cleaning properties. The coatings can also exhibit adequate adaptability for various substrates including wood, polyurethane foam, and cotton fabrics. Besides, good durability and robustness of coatings have been also verified via acid/alkali immersion, outdoor exposure, O2/plasma etching, and linear abrasion tests. Simultaneously, the coatings can exhibit excellent anticorrosion capacity for steel materials via a double barrier effect. Most importantly, the coatings have exhibited the lowest backside temperature (234.5 °C) during fire impact tests, suggesting excellent fireproof and heat insulation performance. This fact can be ascribed to the conjunct action between the physical/chemical charring process of flame retardants and the remarkable thermal stability of graphene. Consequently, this article can be expected to further promote the development and application of multifunctional-integrated coatings for steel structures in more fields.

Repairable body-centered cubic Fe0 anchoring on porous hollow nitrogen-doped carbon spheres with adjusting electron distribution for efficient electrocatalytic ammonia synthesis.

Electrocatalytic nitrogen reduction reaction (ENRR) is a promising and efficient method for ammonia production. However, ENRR is restricted by the adsorption and activation of N2. Herein, an efficient nitrogen reduction reaction (NRR) electrocatalyst loaded with zero valent iron (ZVI) particles onto porous nitrogen-doped carbon (NC) hollow spheres is reported. The optimal Fe@10N3C-950 exhibits excellent performance with high ammonia (NH3) yield (152.28 µg h-1 mgcat-1) and Faradaic efficiency (FE, 54.55 %) at - 0.3 V (versus reversible hydrogen electrode, vs. RHE). Bader charge shows that the adsorbed N2 acquires more electrons from Fe sites with body-centered cubic (BCC) structure to better activate N2. Moreover, i-t experiments are performed before electrocatalytic NH3 production to effectively eliminate the effect of oxidation on ZVI and thus, maintain high ENRR activity for Fe@10N3C-950. Theoretical calculations indicate that nitrogen doping not only reduces the Gibbs free energy of rate determining step (RDS), but the BCC-structured Fe can also decrease the energy barriers of N2 activation and RDS.

Fabrication of cellulose-based halogen-free flame retardant and its synergistic effect with expandable graphite in polypropylene.

In this paper, a mono-component, cellulose-based and intumescent halogen-free flame retardant (HECPM) was prepared by introducing phosphate groups and melamine groups onto the structure of cellulose. And the chemical structure and surface morphology of HECPM was confirmed by FTIR, EDS and SEM, respectively. The thermal degradation tests demonstrate HECPM possesses great expansion property during the inducement of heat and the char residue of HECPM is higher than 43% at 600 °C. Moreover, the synergistic effect of HECPM and EG in flame-retarding polypropylene (PP) was also verified. When 30% HECPM/EG in ratio of 1/3 were introduced into PP, the LOI value reaches 31.5% and it can obtain UL-94 V-0 rating. The conjunct action of HECPM and EG in promoting the char-forming process was also achieved in comparison with the calculated and experimental TGA curves. Along with the investigation on the residue, a potential condensed-phase flame retardant mechanism was primarily proposed.

Fabrication of a Novel and High-Performance Mesoporous Ethylene Tar-Based Solid Acid Catalyst for the Dehydration of Fructose into 5-Hydroxymethylfurfural.

In this article, a novel and high-performance mesoporous carbon-based solid acid catalyst was prepared using ethylene tar (ET) as a precursor, which is a byproduct of ethylene production. First, ET was carbonized at 550 °C by using magnesium acetate as the template. After that, the mesoporous ET-based solid acid catalyst was obtained by a one-step sulfonation process that removes the templates simultaneously. On the basis of these facts, the maximum yield of 5-hydroxymethylfurfural (5-HMF) in the presence of an ET catalyst during the dehydration of fructose can reach 87.8%. This effective catalytic activity is mainly attributed to the large specific surface area and high density of sulfonic acid groups existing in the ET catalyst. Moreover, no distinct activity drop was observed during five recycling runs that confirmed good recyclability and thermal stability of the ET catalyst. This research provides a novel and promising method for the utilization of ET as a low-cost, recyclable, and high-performance catalyst.