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The stabilization of transition metals as isolated centres with high areal density on suitably tailored carriers is crucial for maximizing the industrial potential of single-atom heterogeneous catalysts. However, achieving single-atom dispersions at metal contents above 2 wt% remains challenging. Here we introduce a versatile approach combining impregnation and two-step annealing to synthesize ultra-high-density single-atom catalysts with metal contents up to 23 wt% for 15 metals on chemically distinct carriers. Translation to a standardized, automated protocol demonstrates the robustness of our method and provides a path to explore virtually unlimited libraries of mono- or multimetallic catalysts. At the molecular level, characterization of the synthesis mechanism through experiments and simulations shows that controlling the bonding of metal precursors with the carrier via stepwise ligand removal prevents their thermally induced aggregation into nanoparticles. The drastically enhanced reactivity with increasing metal content exemplifies the need to optimize the surface metal density for a given application. Moreover, the loading-dependent site-specific activity observed in three distinct catalytic systems reflects the well-known complexity in heterogeneous catalyst design, which now can be tackled with a library of single-atom catalysts with widely tunable metal loadings. A general versatile approach combining wet-chemistry impregnation and two-step annealing is devised for the scalable synthesis of a library of ultra-high-density single-atom catalysts with drastically enhanced reactivity.

Magnetic pore fabrics (MPF) are an efficient way to characterize pore space anisotropy, i.e., the average pore shape and orientation. They are determined by impregnating rocks with ferrofluid and then measuring their magnetic anisotropy. Obtaining even impregnation of the entire pore space is key for reliable results, and a major challenge in MPF studies. Here, impregnation efficiency and its spatial variability are systematically tested for natural (wood, rock) and synthetic (gel) samples, using oil- and water-based ferrofluids, and comparing various impregnation methods: percolation, standard vacuum impregnation, flowthrough vacuum impregnation, immersion, diffusion, and diffusion assisted by magnetic forcing. Seemingly best impregnation was achieved by standard vacuum impregnation and oil-based ferrofluid (76%), and percolation (53%) on rock samples; however, sub-sampling revealed inhomogeneous distribution of the fluid within the samples. Flowthrough vacuum impregnation yielded slightly lower bulk impregnation efficiencies, but more homogeneous distribution of the fluid. Magnetically assisted diffusion led to faster impregnation in gel samples, but appeared to be hindered in rocks by particle aggregation. This suggests that processes other than the mechanical transport of nanoparticles in the pore space need to be taken into account, including potential interactions between the ferrofluid and rock, particle aggregation and filtering. Our results indicate that bulk measurements are not sufficient to assess impregnation efficiency. Since spatial variation of impregnation efficiency may affect MPF orientation, degree and shape, impregnation efficiency should be tested on sub-samples prior to MPF interpretation. Article Highlights Even ferrofluid impregnation is a key prerequisite for reliable pore fabric characterization by magnetic methods Spatial variability of impregnation efficiency on sub-samples suggests that flow-through methods provide homogeneous impregnation Successful impregnation depends on pore size, wettability, existing pore fluid, impregnation method, and ferrofluid-sample interactions

This study aimed to determine the amount of flame retardant for semi-combustible performance required to comply with the Ministry of Land, Infrastructure, and Transport Notice 2023-24 for hinoki cypress (Chamaecyparis obtusa) plywood, which is commonly used as a building material. A cone calorimeter was used to observe the changes in the total heat release (THR) depending on the solid content of the flame-retardant impregnation (SCFI). The relationship between the SCFI and THR was expressed as an exponential function. The solid content of the flame-retardant impregnation required to meet the prescribed standard of 8.0 MJ/m² was 108 kg/m³ (semi-combustible performance standards) for hinoki cypress plywood.

In this paper, a wood-SiO2 composite material was prepared via in-situ polymerization using vacuum/pressure impregnation technology using commercial scale nano silica sol and Chinese Fir (Cunninghamia lanceolate (Lamb.) Hook.). Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG), and water contact angle were used to study the changes in the microstructure and physical and mechanical properties of this composite. The results showed that silica sol can penetrate and distribute into the wood cell cavities and surface of cell walls and hence combine with the substances of wood materials. FTIR results indicated that the –OH groups of wood can polycondense in-situ with silica sol to form Si–O–C covalent bonds, and amorphous SiO2 formed from Si–O–Si bonds between the –OH groups of silica sol did not change the crystalline structure of wood cell walls. This in-situ formulating composite significantly improved the compact microstructure, thermal and mechanical properties, and hydrophobicity of the composites.

One of the most significant disadvantages of wood materials is increased combustibility. Therefore, the problem of reducing the combustibility of wood materials is relevant. The article describes an experimental study of impregnation of wood using biopiren MIG-09, which is a hybrid composition on a salt basis with the addition of functional substances of non-salt nature, at different temperature regimes. Two stages of the study were chosen for the experiment. The optimum temperature regimes for different methods of applying the composition to increase the fire resistance of wood were established experimentally. Also fire tests were carried out to analyze the degree of penetration of the solution.

PdZn/TiO 2 catalysts have been investigated for the hydrogenation of CO 2 to methanol. Varying the ratio of Pd and Zn using TiO 2 as a support has a dramatic effect on catalytic performance. Chemical vapour impregnation was used to produce PdZn alloys on TiO 2 and X-ray diffraction, X-ray photoelectron spectroscopy, and scanning transmission electron microscopy revealed changes in the structure at varying total PdZn molar ratios. Compared to monometallic Pd/TiO 2 , introducing a low loading of Zn drastically changes product selectivity. When Pd is alloyed with Zn above a total Zn/Pd = 1 molar ratio, methanol selectivity is improved. Therefore, for enhanced methanol productivity, it is crucial for the Zn loading to be higher than that required for the stoichiometric formation of the 1:1 β-PdZn alloy. Graphical Abstract

This work is scrutinizing the development of metallized biochar as a low-cost bio-sorbent for low temperature CO 2 capture with high adsorption capacity. Accordingly, single-step pyrolysis process was carried out in order to synthesize biochar from rambutan peel (RP) at different temperatures. The biochar product was then subjected to wet impregnation with several magnesium salts including magnesium nitrate, magnesium sulphate, magnesium chloride and magnesium acetate which then subsequently heat-treated with N 2 . The impregnation of magnesium into the biochar structure improved the CO 2 capture performance in the sequence of magnesium nitrate > magnesium sulphate > magnesium chloride > magnesium acetate. There is an enhancement in CO 2 adsorption capacity of metallized biochar (76.80 mg g −1 ) compare with pristine biochar (68.74 mg g −1 ). It can be justified by the synergetic influences of physicochemical characteristics. Gas selectivity study verified the high affinity of biochar for CO 2 capture compared with other gases such as air, methane, and nitrogen. This investigation also revealed a stable performance of the metallized biochar in 25 cycles of CO 2 adsorption and desorption. Avrami kinetic model accurately predicted the dynamic CO 2 adsorption performance for pristine and metallized biochar.

One of the biggest technological problems connected with the production of lightweight concretes made of porous aggregates is their much higher water absorption, which may cause on the one hand workability loss, and on the other hand excess water content in concrete. The aim of this research was to assess the effect of impregnation of lightweight aggregates (LWAs) with cement paste on their properties and to verify its effectiveness in concretes. Three types of lightweight aggregates differing in porosity and pore structure (sintered fly ash Lytag, expanded clay: Leca and Liapor) were selected for the tests. The following parameters were taken into consideration in the research program: LWA type and size, LWA initial moisture content, strength, and rheology of cement pastes. The tests of 22 different aggregates, plain and coated with cement paste, included density, crushing strength, and development of water absorption in time. The research program proved that porous aggregates, due to their impregnation with cement pastes, may be effectively sealed and strengthened. All tested LWAs showed a considerable decrease in water absorption by up to 71%. However, only Lytag aggregate showed a visibly enhanced crushing strength. Verification of effectiveness of aggregate sealing on the enhancement of concrete properties showed both a considerable reduction in water absorption of composites (by up to 52%) and a very high increase in their strength (by up to 107%).

Falcataria moluccana or sengon is one of the fast-growing wood species widely grown in Indonesia. However, its wood is low quality with low density, and poor strength, durability, and dimensional stability. This study determined the effects of impregnation with monoethylene glycol (MEG) and nano-SiO 2 on the characteristics of sengon wood, including its dimensional stability and density. Impregnation with MEG and nano-SiO 2 had a significant effects on dimensional stability in terms of the weight percent gain, anti-swelling efficiency, water uptake, bulking effect, and density. The impregnated wood was examined by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction. The results show that MEG and nano-SiO 2 were distributed homogeneously into cell walls of wood treated with 0.5% MEGSiO 2 .

Activated carbon refers to a wide range of carbonised materials of high degree of porosity and high surface area. Activated carbon has many applications in the environment and industry for the removal, retrieval, separation and modification of various compounds in liquid and gas phases. Selection of the chemical activator agent is a major step controlling the performance and applicability of activated carbon. Here, we review chemical activators used to produce activated carbon. We compare the impregnation method with the physical mixing method used in activating with alkali hydroxides. We selected 81 articles from Google Scholar, PubMed, Scopus, Science Direct, Embase and Medlin databases. Eighteen articles report the activation with potassium hydroxide, 17 with phosphoric acid, 15 with zinc chloride, 11 with potassium carbonate, nine with sodium hydroxide, and 11 with new activating agents. Activation with phosphoric acid is commonly used for lignocellulosic material and at lower temperatures. Zinc chloride generates more surface area than phosphoric acid but is used less due to environmental concerns. Potassium carbonate, in comparison with potassium hydroxide, produces higher yields and a higher surface area for the adsorption of large pollutant molecules such as dyes. Activating with potassium hydroxide in terms of surface area and efficiency shows better results than sodium hydroxide for various applications. Also, the comparison of the physical mixing method and the impregnation method in activation with alkali metals indicates that the activated carbon obtained through physical mixing had a higher porosity than the activated carbon produced by the impregnation method.