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• Efficient supercritical flow process for selective valorisation of CO 2 into methanol. • Catalyst ReO x /TiO 2 composed of rhenium oxide nanoparticles supported on P25. • High pressure, low temperature process which does not require any solvents or additives. • High selectivity towards methanol (98%) at ∼20% conversion of CO 2. • Supercritical CO 2 improved CH 3 OH selectivity, and maintained reaction mixture homogeneous. Methanol plays a crucial role in the novel cycle of carbon capture, recycling and valorisation of anthropogenic carbon dioxide (CO 2). Even though hydrogenation of CO 2 to methanol has favourable thermodynamics, catalyst and processes development is needed for improving stability, reaction rate and selectivity to higher values than of the currently used copper oxide on zinc oxide (CuO/ZnO) catalysts. Here we report an efficient supercritical flow process for the selective valorisation of CO 2 into methanol. At optimized conditions, rhenium oxide on titanium dioxide (ReO x /TiO 2) catalyst converts CO 2 into methanol with 98% selectivity and at 18% CO 2 conversion rate at 200 °C, 100 bar and CO 2 /H 2 ratio of 1/4. A higher conversion of 41% can be achieved at 250 °C, but the selectivity towards methanol decreases to 64%. This strategy has enabled the development of an efficient high-pressure flow process without compromising methanol selectivity. [ABSTRACT FROM AUTHOR]

Abstract A pH-triggered bistable copper(II) complex acts as a molecular machine in which a molecular movement can be driven by the pH and the complex assumes deprotonate [Cu 2 L 2 ]4− (1) or protonate form [Cu 2 (H 2 L) 2 ] (2), where H 2 L = N , N ′‑ 2 , 2 ′‑ethylenediphenylenebis(oxamic acid). 1 and 2 were used as templates during the hydrolysis of TEOS in aqueous medium at pH 12 and 5, respectively, resulting in meso (1 @SiO 2) and microporous (2 @SiO 2) silica-based hybrid materials without using conventional surfactants. The [Cu 2 L 2 ]4− complex species leads to non-organized mesoporous silica nanostructures with specific surface area equal to 106 m2 g−1, while the microporous material 2 @SiO 2 presents surface area almost four times higher (409 m2 g−1). Furthermore, it was possible to reversibly deprotonate the oxamate-based ligand in 2 @SiO 2 , leading to the formation of the tetra-anionic (pH = 12) species inside the microporous silica in a post-synthetic procedure. Both hybrid materials were characterized by FTIR, thermal analyses (TGA/DTA), PXRD, TEM, adsorption/desorption of N 2 , and TXRF in order to stablish a correlation between structure-catalytic activity. Due to its higher surface area, the efficiency of 2 @SiO 2 as heterogeneous catalyst in mild oxidation of benzyl alcohol (BzOH) by using H 2 O 2 was evaluated, as well as its selectivity and recyclability. Graphical abstract Unlabelled Image Highlights • Hybrid porous silica were prepared in mild conditions (40 °C and 1 atm) without using classic surfactants as templates. • A pH-triggered bistable copper(II) complex was pioneered as a template in obtaining hybrid porous silica. • The processing pH controls the porosity leading to mesoporous silica (25 nm; pH = 4) or microporous silica (1.6 nm; pH = 12). • The bistable copper(II) complex creates the microporosity acting as an encapsulated molecular machine. • The microporous hybrid material acts as a pH-dependent heterogeneous catalyst under mild conditions towards the oxidation of BzOH. [ABSTRACT FROM AUTHOR]

The increase in the consumption of fossil fuels led not only to the increase of atmospheric CO 2 level, but also to the increment in sulfur pollutants production, such as SO 2. The electrochemical SO 2 oxidation reaction (SO 2 OR) was already shown to be efficiently catalyzed by Au and, to further develop the technological knowledge in this field, the application of nanostructured Au catalysts is highly desirable. Herein we present a highly dispersed subnanometric Au/TiO 2 catalyst as active material for SO 2 OR. The Tafel analysis revealed a change in the reaction mechanism and a substantial increase of the electrocatalytic reaction activity compared to bulk Au, even at conditions where bulk Au presented low activity, such as H 2 SO 4 electrolyte. Electrochemical impedance spectroscopy (EIS) results led to the conclusion that TiO 2 is also involved in the reaction, since not only the oxide time constant changes with the applied potential but also adsorbed intermediates were observed. This EIS response is probably related to the Au/TiO 2 interface, which reflects on the oxide time constant. [ABSTRACT FROM AUTHOR]

Most adsorption experiments are performed under conditions that did not exist on Earth before the life arose on it. Because adsorption is the first step for all other processes (protection against degradation and polymerization), it is important that it is performed under conditions that existed on prebiotic Earth. In this paper, we use an artificial seawater (seawater 4.0 Ga), which contains major cations and anions that could present on the oceans of the prebiotic Earth. In addition, zeolites, with substituted Fe in the framework, and adenine were probably common substances on the prebiotic Earth. Thus, study the interaction between them is an important issue in prebiotic chemistry. There are two main findings described in this paper. Firstly, zeolites with different Si/Fe ratios adsorbed adenine differently. Secondly, XAFS showed that, after treatments with seawater 4.0 Ga and adenine, an increase in the complexity of the system occurred. In general, salts of seawater 4.0 Ga did not affect the adsorption of adenine onto zeolites and adenine adsorbed less onto zeolites with iron isomorphically substituted. The C C and NH 2 groups of adenine interacted with the zeolites. Gypsum, formed from aqueous species dissolved in seawater 4.0 Ga, precipitated onto zeolites. EPR spectra of zeolites showed lines caused by Fe framework and Fe 3+ species. TG curves of zeolites showed events caused by loss of water weakly bound to zeolite (in the 30–140 °C range), water bounded to iron species or cations from seawater 4.0 Ga or located in the cavities of zeolites (157–268 °C) and degradation of adenine adsorbed onto zeolites (360–600 °C). Mass loss follows almost the same order as the amount of adenine adsorbed onto zeolites. The XAFS spectrum showed that Fe 3+ could be substituted into the framework of the Fe 7 -ZSM-5 zeolite. [ABSTRACT FROM AUTHOR]

• [CeO 2 ] 100- x -[S 8 ] x nanohybrids are prepared by a simple and rapid synthetic approach. • The [CeO 2 ] 70 -[S 8 ] 30 nanohybrid presents a capacity of 600 mA h g–1 over 160 cycles. • [CeO 2 ] 70 -[S 8 ] 30 promotes fast redox reactions, making the shuttle effect negligible. • DFT results reveal strong interactions between the CeO 2 surface and sulfur species. An in-depth investigation of the physical and chemical parameters that affect Li-sulfur batteries is imperative to optimize their performances. Here, we report promising [CeO 2 ] 100- x -[S 8 ] x nanohybrids for anchoring lithium polysulfides (LiPSs) that are generated during cycling. The composition of [CeO 2 ] 100- x -[S 8 ] x (x = 30, 50 and 70%) could be simply controlled by varying the CeO 2 /S 8 mass ratio added in each reaction. Our results indicated that the [CeO 2 ] 100- x -[S 8 ] x nanohybrids displayed a crystalline structure composed of both phases (CeO 2 and S 8), indicating an efficient impregnation process of S 8 on the CeO 2 nanowire surface. The surface area of CeO 2 nanowires decreased as the amount of S 8 was increased, and the [CeO 2 ] 70 -[S 8 ] 30 nanohybrid maintained a uniform distribution of S 8 over the entire CeO 2 nanowires. Remarkably, the [CeO 2 ] 70 -[S 8 ] 30 nanohybrid showed the best Li-storage performance, leading to specific capacities of approximately 600 mA h g–1 over 160 cycles and a Coulombic efficiency of approximately 100%. Moreover, this sample showed excellent rate capability performance (even discharging at 10 A g–1). Additionally, the chemical interaction of CeO 2 with LiPS was demonstrated by a visual experiment through the addition of pure CeO 2 in a solution of Li 2 S 6. The solution containing CeO 2 nanowires became completely colorless after 30 min. To further investigate these improvements, density functional theory (DFT) calculations revealed the formation of strong interactions between the CeO 2 nanowire surface and different sulfur species. For instance, the adsorption energies between the CeO 2 nanowires and S 8 , Li 2 S 4 , and Li 4 S 8 were –3.95, –5.84 and –7.31 eV, respectively, suggesting that the [CeO 2 ] 70 -[S 8 ] 30 nanohybrid provided an appropriate surface to anchor LiPS by electrostatic interactions, leading to faster redox kinetics in Li-sulfur battery applications. [Display omitted] [ABSTRACT FROM AUTHOR]