Adsorption Of Organic Molecules Research Articles

Influence of Organic Matter/Bacteria on the Formation and Transformation of Sulfate Green Rust

The corrosion processes of carbon steel immersed in natural seawater are influenced by microorganisms due to important biological activity. An analysis of the corrosion product layers formed on carbon steel coupons in natural or artificial seawater revealed that sulfate green rust GR(SO42−) was favored in natural environments. In this paper, the role of organic matter/bacteria on the formation and transformation of this compound are addressed. GR(SO42−) was precipitated from Fe(II) and Fe(III) salts in the presence of various marine bacterial species not involved in the redox cycle of Fe or S. Abiotic experiments were performed for comparison, first without any organic species and then with sodium acetate added as a small organic ion. The obtained aqueous suspensions were aged at room temperature for 1 week. The number of bacteria (CFU/mL) was followed over time and the solid phases were characterized by XRD. Whatever the fate of the bacteria (no activity, or activity and growth), the formation of GR(SO42−) was favored and its transformation to magnetite completely inhibited. This effect is attributed to the adsorption of organic molecules on the lateral sides of the GR(SO42−) crystals. A similar effect, though less important, was observed with acetate.

Enhanced selective adsorption and photocatalytic of Ag/Bi2O3 heterostructures modified up-conversion nanoparticles

The degradation of organic pollutant by photocatalytic technology is an emerging and effective approach to purify water resources. Herein, we reported a heterostructure with selective adsorption and photocatalysis for the efficient removal of organic pollutant. The photocatalyst was comprised of up-converting nanoparticle (UCNP) coated with Ag/Bi2O3. The specific crystallinity of Bi2O3 facilitated the selective adsorption of organic molecules with negative polarity, Ag nanoparticles loaded on Bi2O3 promoted the visible light absorption, and the up-conversion property of UCNP turned near-infrared light into ultraviolet and visible light improving further light-harvesting efficiency in the whole solar spectrum. The adsorption process for organic pollutants over Ag/UCNP@Bi2O3 obeyed the pseudo-second-order and the Langmuir isotherm models, and the maximum Langmuir adsorption capacity for tetracycline reached to 717.4 mg/g at pH 7. Meanwhile, the photocatalytic degradation rate of Ag/UCNP@Bi2O3 for tetracycline (100 mg/L) achieved to 0.0037 min−1 under Xenon lamp irradiation after the adsorption equilibrium. This study provided a feasible strategy to develop photocatalysts with efficient adsorption and photocatalytic ability for organic pollutant from water.

Organic molecule intercalation sites in Sr2CaCu2Oy superconductor

AbstractThe organic molecule adsorption sites in a Sr2CaCu2Oy (0(Sr)212) half unit cell upon water molecule intercalation were estimated by simulation using Molecular Orbital PACkage (MOPAC) program. For water molecules, the unit cell was elongated with increasing the number of molecules. Upon four water molecules intercalated between the two SrO layers, the upper Sr atom moved along the c‐axis by 1.49 Å. This value was smaller than but comparable to the experimentally obtained elongation of half of the c‐parameter. The primary reason of the elongation is the repulsive force between Sr–H atoms in the two SrO layers. For ethanol and acetone molecules, stable intercalation sites were not found in the 0(Sr)212 crystal. These results coincided to the experimental results, which did not show intercalations. It was concluded that MOPAC can reproduce the organic molecule intercalation phenomena in oxide crystals.

Photocatalytic Degradation of Sugarcane Vinasse Using ZnO Photocatalyst: Operating Parameters, Kinetic Studies, Phytotoxicity Assessments, and Reusability.

Photocatalytic degradation performance is highly related to optimized operating parameters such as initial concentration, pH value, and catalyst dosage. In this study, the impact of various parameters on the photocatalytic degradation of anaerobically digested vinasse (AnVE) has been determined through decolourization and chemical oxygen demand (COD) reduction efficiency using zinc oxide (ZnO) photocatalyst. In this context, the application of photocatalytic degradation in treating sugarcane vinasse using ZnO is yet to be explored. The COD reduction efficiency and decolourization achieved 83.40% and 99.29%, respectively, under the conditions of 250 mg/L initial COD concentration, pH 10, and 2.0 g/L catalyst dosage. The phytotoxicity assessment was also conducted to determine the toxicity of AnVE before and after treatment using mung bean (Vigna radiata). The reduction of root length and the weight of mung bean indicated that the sugarcane vinasse contains enormous amounts of organic substances that affect the plant's growth. The toxicity reduction in the AnVE solution can be proved by UV–Vis absorption spectra. Furthermore, the catalyst recovery achieved 93% in the reusability test. However, the COD reduction efficiency and decolourization were reduced every cycle. It was due to the depletion of the active sites in the catalyst with the adsorption of organic molecules. Thus, it can be concluded that the photocatalytic degradation in the treatment of AnVE was effective in organic degradation, decolorization, toxicity reduction and can be reused after the recovery process.Graphical abstract

Tuning the carrier type and density of monolayer tin selenide via organic molecular doping

Utilizing first-principles calculations, charge transfer doping process of single layer tin selenide (SL-SnSe) via the surface adsorption of various organic molecules was investigated. Effective p-type SnSe, with carrier concentration exceeding 3.59 × 1013 cm−2, was obtained upon adsorption of tetracyanoquinodimethane or 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane on SL-SnSe due to their lowest unoccupied molecular orbitals acting as shallow acceptor states. While we could not obtain effective n-type SnSe through adsorption of tetrathiafulvalene (TTF) or 1,4,5,8-tetrathianaphthalene on pristine SnSe due to their highest occupied molecular orbitals (HOMO) being far from the conduction band edge of SnSe, this disadvantageous situation can be amended by the introduction of an external electric field perpendicular to the monolayer surface. It is found that Snvac will facilitate charge transfer from TTF to SnSe through introducing an unoccupied gap state just above the HOMO of TTF, thereby partially compensating for the p-type doping effect of Snvac. Our results show that both effective p-type and n-type SnSe can be obtained and tuned by charge transfer doping, which is necessary to promote its applications in nanoelectronics, thermoelectrics and optoelectronics.

A novel covalent organic framework with multiple adsorption sites for removal of Hg2+ and sensitive detection of nitrofural

It is urgent to control serious drug pollution and heavy metal ion pollution. Covalent organic framework (COF) is becoming a promising material for the removal of heavy metal ion and adsorption of organic small molecule because of the designed functional sites, ordered pore channel, high specific surface area and abundant π electrons. Herein, 2,4,6-triformylphloroglucinol (TFP) and benzene-1,3,5-tricarbohydrazide (BTH) was used to design a stable yet efficient beta-ketoenamine COF (COFTFP-BTH) adsorbent, which would provide multiple adsorption sites of Hg2+ by dense acylhydrazine. The maximum adsorption capacity of COFTFP-BTH toward Hg2+ achieved 909 mg g−1, coinciding with Langmuir adsorption and pseudo-second-order adsorption kinetic model, with the h value as high as 71.43 mg g−1 min−1. COFTFP-BTH was also grown on NH2-carbon nanotubes (CNT) to form a novel COFTFP-BTH@NH2-CNT composite for sensitive detection of nitrofural (NF). The NF sensor based on COFTFP-BTH@NH2-CNT showed a low detection limit (3.2 nM) and a wide linear range (9.6 nM-100 μM). The excellent performances were also attributed to the ordered channels of COFTFP-BTH exposing more adsorption sites of Hg2+ and NF, as well as the good stability of beta-ketoenamine COFTFP-BTH.

Mechanisms of soil organic carbon stability and its response to no-till: A global synthesis and perspective.

Mechanisms of soil organic carbon (SOC) stabilization have been widely studied due to their relevance in the global carbon cycle. No-till (NT) has been frequently adopted to sequester SOC; however, limited information is available regarding whether sequestered SOC will be stabilized for long term. Thus, we reviewed the mechanisms affecting SOC stability in NT systems, including the priming effects (PE), molecular structure of SOC, aggregate protection, association with soil minerals, microbial properties, and environmental effects. Although a more steady-state molecular structure of SOC is observed in NT compared with conventional tillage (CT), SOC stability may depend more on physical and chemical protection. On average, NT improves macro-aggregation by 32.7%, and lowers SOC mineralization in macro-aggregates compared with CT. Chemical protection is also important due to the direct adsorption of organic molecules and the enhancement of aggregation by soil minerals. Higher microbial activity in NT could also produce binding agents to promote aggregation and the formation of metal-oxidant organic complexes. Thus, microbial residues could be stabilized in soils over the long term through their attachment to mineral surfaces and entrapment of aggregates under NT. On average, NT reduces SOC mineralization by 18.8% and PE intensities after fresh carbon inputs by 21.0% compared with CT (p<.05). Although higher temperature sensitivity (Q10 ) is observed in NT due to greater Q10 in macro-aggregates, an increase of soil moisture regime in NT could potentially constrain the improvement of Q10 . This review improves process-based understanding of the physical and chemical mechanism of protection that can act, independently or interactively, to enhance SOC preservation. It is concluded that SOC sequestered in NT systems is likely to be stabilized over the long term.

Tailoring Competitive Adsorption Sites by Oxygen-Vacancy on Cobalt Oxides to Enhance the Electrooxidation of Biomass.

The electrooxidation of 5-hydroxymethylfurfural (HMF) offers a promising green route to attain high-value chemicals from biomass. The HMF electrooxidation reaction (HMFOR) is a complicated process involving the combined adsorption and coupling of organic molecules and OH- on the electrode surface. An in-depth understanding of these adsorption sites and reaction processes on electrocatalysts is fundamentally important. Herein, the adsorption behavior of HMF and OH- , and the role of oxygen vacancy on Co3 O4 are initially unraveled. Correspondingly, instead of the competitive adsorption of OH- and HMF on the metal sites, it is observed that the OH- can fill into oxygen vacancy (Vo) prior to couple with organic molecules through lattice oxygen oxidation reaction process, which could accelerate the rate-determining step of the dehydrogenation of 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) intermediates. With the modulated adsorption sites, the as-designed Vo-Co3 O4 shows excellent activity for HMFOR with the earlier potential of 90 and 120mV at 10mA cm-2 in 1 m KOH and 1 m PBS solution. This work sheds insight on the catalytic mechanism of oxygen vacancy, which benefits designing a novel electrocatalysts to modulate the multi-molecules combined adsorption behaviors.

Performance and poisoning analysis of organic sulfur resistance of Pd-Ce catalyst in catalytic oxidation of VOCs

In this paper, the effect of organic sulfur on the catalytic oxidation of toluene was explored. It was found that the low concentration of organic sulfur could cause rapid deactivation of the catalyst, and the activity of the catalyst could be restored to 100% after stopping the application of sulfur. The sulfation modification could significantly improve the organic sulfur resistance of the catalyst by changing the support and the sulfation modification of the support. There was a large amount of carbon deposition and a small amount of S-containing substances on the catalyst surface after the introduction of organic sulfur through the methods of TG, BET, FTIR, SEM (Mapping) and XPS. Then, through in-situ DRIFT and CH3SH-TPD, it was found that sulfation modification could inhibit the adsorption of organic sulfur on the catalyst surface and reduce the competitive adsorption. The decrease of catalyst efficiency due to the presence of organic sulfur in the reaction gas during VOCs catalytic oxidation is mainly due to the competitive adsorption of organic sulfur and VOCs molecules, and the temperature of VOCs catalytic oxidation of organic sulfur. Some polyhydrocarbons, ethyl sulfide, dimethyl sulfoxide and other substances were produced by incomplete oxidation, which covered the surface of the catalyst due to adsorption or deposition, resulting in catalyst poisoning.

Electrocatalytic Hydrogenation of unsaturated Aldehydes – Influence of External Electric Potential and Promotor Species on Carbonyl Group Activation

The production of chemicals and fuels via transformation of biomass-derived feedstock requires the hydrodeoxygenation of oxygenated intermediates (e.g. carboxylic acids, aldehydes or phenolic compounds).[1] Usually, this step is done by thermal hydrogenation at elevated temperatures and high pressures, in which the reacting hydrogen is still supplied from reforming of non-sustainable fossil resources. These drawbacks make the hydrogenation of oxygen-containing intermediates the most energy- and capital-intensive step during the biomass upgrading process.[2] Electrocatalytic hydrogenation, in contrary, is a promising, sustainable technology for the ambient reduction of organic molecules. The required hydrogen is produced in situ from reduction of hydronium ions or electrolysis of water that is driven by renewable resources.[3] Especially, the selective hydrogenation of α,β-unsaturated aldehydes towards their corresponding unsaturated alcohols has proven difficult in the past, even under thermal conditions (ΔpH2, ΔT).[4] When using common hydrogenation catalysts that are based on noble metals, e.g. Pd, Rh, Ru, hydrogenation of the double bond towards saturated aldehydes is by far more likely than conversion of the carbonyl moiety.[5] Therefore, researchers have put lots of efforts in developing new catalysts that are capable of selectively converting α,β-unsaturated aldehydes towards unsaturated alcohols under thermal conditions. The addition of promotors specifically activating the CO-bond, e.g. metal oxide species, oxophilic metals, is one approach that has proven beneficial in tuning the reaction selectivity.[6] Another approach towards selective hydrogenation of the carbonyl group is the repulsion of the double bond away from the catalyst surface either electrostatically via changing the charge density on the catalyst surface or sterically via particle size effects.[7] The present study investigates the electrocatalytic hydrogenation of trans-pent-2-en-1-al and trans-cinnamaldehyde on transition metal catalysts supported on carbon nanotubes in aqueous phase (Scheme 1). The influence of different noble metals as well as promotor species on the reaction selectivity, especially concerning the formation of α,β-unsaturated alcohols, is analyzed. Furthermore, the impact of an external electric potential on product distribution and reaction kinetics is evaluated. The effect of different metals, promotors as well as the presence of an external electric potential on the kinetic data shall be related to adsorption measurements of organic species on the catalyst surface both via cyclic voltammetry (CV) and UV/VIS-spectroscopy.In a recent study, we have shown that adding phenol to an aqueous electrolyte gradually blocks sites for H adsorption and hence, diminishes the Hupd peaks in CV curves recorded on Pt.[8] Now, we are seeking to correlate these findings with adsorption isotherms measured via UV/VIS absorption spectroscopy in order to answer the question whether different moieties, e.g. double bond, carbonyl group, lead to changes in the adsorption and activation of organic molecules on the electrode surface that can explain the differences in reaction kinetics and product distribution. Furthermore, we want to shed light on the influence of increasing the negative charge density on the electrode during ECH on electrostatic repulsion of electron-rich moieties away from the catalyst surface. First results on the hydrogenation of trans-pent-2-en-1-al showed that in case of ECH the yield of alcohol was increased by two orders of magnitude compared to thermal hydrogenation.[1] Y. Song, O. Y. Gutiérrez, J. Herranz, J. A. Lercher, Applied Catalysis B: Environmental 2016, 182, 236-246.[2] Y. Song, U. Sanyal, D. Pangotra, J. D. Holladay, D. M. Camaioni, O. Y. Gutiérrez, J. A. Lercher, Journal of Catalysis 2018, 359, 68-75.[3] U. Sanyal, J. Lopez-Ruiz, A. B. Padmaperuma, J. D. Holladay, O. Y. Gutiérrez, Organic Process Research & Development 2018, 22, 1590-1598.[4] a) P. Gallezot, D. Richard, Catalysis Reviews 1998, 40, 81-126; b) P. Claus, Topics in Catalysis 1998, 5, 51-62.[5] a) X. Lan, T. Wang, ACS Catalysis 2020, 10, 2764-2790; b) C. Louis, L. Delannoy, in Advances in Catalysis, Vol. 64 (Ed.: C. Song), Academic Press, 2019, pp. 1-88.[6] a) M. Tamura, K. Tokonami, Y. Nakagawa, K. Tomishige, ACS Catalysis 2016, 6, 3600-3609; b) Y. Dai, X. Gao, X. Chu, C. Jiang, Y. Yao, Z. Guo, C. Zhou, C. Wang, H. Wang, Y. Yang, Journal of Catalysis 2018, 364, 192-203; c) N. Mahata, F. Gonçalves, M. F. R. Pereira, J. L. Figueiredo, Applied Catalysis A: General 2008, 339, 159-168.[7] E. Bailón-García, F. J. Maldonado-Hódar, A. F. Pérez-Cadenas, F. Carrasco-Marín, Catalysts 2013, 3.[8] N. Singh, U. Sanyal, J. L. Fulton, O. Y. Gutiérrez, J. A. Lercher, C. T. Campbell, ACS Catalysis 2019. Figure 1

Facile Synthesis of Atomic Fe-N-C Materials and Dual Roles Investigation of Fe-N4 Sites in Fenton-Like Reactions.

Fenton‐like reactions with persulfates as the oxidants have attracted increasing attentions for the remediation of emerging antibiotic pollutions. However, developing effective activators with outstanding activities and long‐term stabilities remains a great challenge in these reactions. Herein, a novel activator is successfully synthesized with single iron atoms anchored on porous N‐doped carbon (Fe‐N‐PC) by a facile chemical vapor deposition (CVD) method. The single Fe atoms are coordinated with four N atoms according to the XANES, and the Fe‐N4‐PC shows enhanced activity for the activation of peroxymonosulfate (PMS) to degrade sulfamethoxazole (SMX). The experiments and density functional theory (DFT) calculations reveal that the introduction of single Fe atoms will regulate the main active sites from graphite N into Fe‐N4, thus could enhance the stability and tune the PMS activation pathway from non‐radical into radical dominated process. In addition, the N atoms connected with single Fe atoms in the Fe‐N4‐C structure can be used to enhance the adsorption of organic molecules on these materials. Therefore, the Fe‐N4‐C here has dual roles for antibiotics adsorption and PMS activation. The CVD synthesized Fe‐N4‐C shows enhanced performance in persulfates based Fenton‐like reactions, thus has great potential in the environmental remediation field.

Design of 3D Carbon Nanotube Monoliths for Potential-Controlled Adsorption

The design of 3D monoliths provides a promising opportunity to scale the unique properties of singular carbon nanotubes to a macroscopic level. However, the synthesis of carbon nanotube monoliths is often characterized by complex procedures and additives impairing the later macroscopic properties. Here, we present a simple and efficient synthesis protocol leading to the formation of free-standing, stable, and highly conductive 3D carbon nanotube monoliths for later application in potential-controlled adsorption in aqueous systems. We synthesized monoliths displaying high tensile strength, excellent conductivity (up to 140 S m−1), and a large specific surface area (up to 177 m2 g−1). The resulting monoliths were studied as novel electrode materials for the reversible electrosorption of maleic acid. The process principle was investigated using chronoamperometry and cyclic voltammetry in a two-electrode setup. A stable electrochemical behavior was observed, and the synthesized monoliths displayed capacitive and faradaic current responses. At moderate applied overpotentials (± 500 mV vs. open circuit potential), the monolithic electrodes showed a high loading capacity (~20 µmol g−1) and reversible potential-triggered release of the analyte. Our results demonstrate that carbon nanotube monoliths can be used as novel electrode material to control the adsorption of small organic molecules onto charged surfaces.

Rapid fabrication of zwitterionic coating on 316L stainless steel surface for marine biofouling resistance

Zwitterionic polymers are considered as nontoxic fouling-resistant materials, and have been widely studied in recent years. However, the immobilization of zwitterionic polymers on metal surfaces still suffers from the complicated and time-consuming procedures. In this work, a zwitterionic polydopamine/poly(sulfobetaine methacrylate) (PDA/PSB) coating on 316L stainless steel surface was fabricated by simply immersing in a mixed solution of dopamine, sulfobetaine methacrylate (SB) and oxidants for 30 mins. The anti-fouling performance of PDA/PSB coating was evaluated in terms of organic molecules (protein and polysaccharide) adsorption and microbes (Gram-negative bacterium, Gram-positive bacterium and diatom) adhesion. The results showed that the PDA/PSB coating inhibits the adsorption of BSA and sodium alginate, and further reduces the adhesion of Pseudomonas aeruginosa, Bacillus subtilis and Navicula sp. by more than 99% in 24 h. This research provides an important inspiration for the practical application of zwitterionic polymers in the field of marine anti-fouling.

Momentum and energy dissipation of hot electrons in a Pb/Ag(111) quantum well system

The band structure of multilayer systems plays a crucial role for the ultrafast hot carrier dynamics at interfaces. Here, we study the energy- and momentum-dependent quasiparticle lifetimes of excited electrons in a highly ordered Pb monolayer film on Ag(111) prior and after the adsorption of a monolayer of 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA). Using time-resolved two-photon momentum microscopy with femtosecond visible light pulses, we show that the electron dynamics of the Pb/Ag(111) quantum well system is largely dominated by two types of scattering processes: (i) isotropic intraband scattering processes within the quantum well state (QWS) and (ii) isotropic interband scattering processes from the ${p}_{z}$-like QWS into the Pb ${p}_{x/y}$ band. In the latter case, the Pb QWS acts as an electron source for the momentum space refilling process of the Pb ${p}_{x/y}$ band. This conclusion is confirmed by the modification of the band structure and the quasiparticle dynamics of the Pb/Ag(111) bilayer film after the adsorption of PTCDA. We find both an adsorption-induced suppression of the QWS itself as well as of the refilling process into the Pb ${p}_{x/y}$ band. Our study hence demonstrates the isotropic nature of the momentum-dependent scattering processes of metallic bilayer systems and uncovers a new possibility to selectively tune and control scattering processes occurring in quantum (well) materials by the adsorption of organic molecules.

Reply to comments on: Synthesis and characterization of a novel nickel pillared-clay catalyst: In-situ carbon nanotube–clay hybrid nanofiller from Ni-PILC

A key question for the investigation of the origins of life is to understand the interaction between complex organic molecules and minerals. In this general frame, the present study investigated the nature of the interactions at the molecular level between a ribonucleic acid and ion-exchanged montmorillonites. We observed that the formation of RNA/clay mineral complexes was strongly pH-dependent. In a sufficiently acidic medium, the RNA molecules were intercalated in the interlayer space, in a flat-lying conformation, with a large contribution of electrostatic interactions that may be complemented by hydrogen bonds. The secondary structure of the RNA strands was strongly affected. The presence of different cations such as Na+, Ca2+, Mg2+, and Sr2+ influenced the adsorption of organic molecules. Apparently, metal cations directly took part in the formation of bridges between the negative charges on the mineral surface and the phosphate groups of the biomolecule.

When RNA meets montmorillonite: Influence of the pH and divalent cations

A key question for the investigation of the origins of life is to understand the interaction between complex organic molecules and minerals. In this general frame, the present study investigated the nature of the interactions at the molecular level between a ribonucleic acid and ion-exchanged montmorillonites. We observed that the formation of RNA/clay mineral complexes was strongly pH-dependent. In a sufficiently acidic medium, the RNA molecules were intercalated in the interlayer space, in a flat-lying conformation, with a large contribution of electrostatic interactions that may be complemented by hydrogen bonds. The secondary structure of the RNA strands was strongly affected. The presence of different cations such as Na+, Ca2+, Mg2+, and Sr2+ influenced the adsorption of organic molecules. Apparently, metal cations directly took part in the formation of bridges between the negative charges on the mineral surface and the phosphate groups of the biomolecule.

Br-Doped CuO Multilamellar Mesoporous Nanosheets with Oxygen Vacancies and Cetyltrimethyl Ammonium Cations Adsorption for Optimizing Intermediate Species and Their Adsorption Behaviors toward CO2 Electroreduction to Ethanol with a High Faradaic Efficiency.

It is a prospective tactic to actualize the carbon cycle via CO2 electroreduction reaction (CO2ER) into ethanol, where the crucial point is to design highly active and selective electrocatalysts. In this work, Br-doped CuO multilamellar mesoporous nanosheets with oxygen vacancies and cetyltrimethyl ammonium (CTA+) cations adsorption were synthesized on Cu foam by one-step liquid-phase method at room temperature. The nanosheets with numerous mesopores and rough edges provided abundant active sites for the adsorption of CO2 molecules and brought about a long retention time for intermediates. The dopant of Br- ions induced copious oxygen vacancies on CuO lattices, thereby reducing the activation energy of CO2 molecules and optimizing intermediate species and their adsorption behaviors, while adsorbed CTA+ cations modulated the O affinity of the Cu sites, favoring *OCH2CH3 intermediate converting to ethanol. The optimized Br1.95%-CuO can effectively catalyze CO2ER to C2H5OH in 0.1 M KHCO3. The faradaic efficiency of C2H5OH reached 53.3% with the partial current density of 7.1 mA cm-2 at a low potential of -0.6 V. In addition, after 14 h CO2ER test at -0.6 V, the current density and faradaic efficiency of C2H5OH on Br1.95%-CuO retained 99.6 and 93.9% of their original values, respectively, indicating its prominent catalytic stability. This work provided a novel strategy for designing a CuO catalyst by nonmetal doping and long-chain organic molecules adsorption with multiple active sites for optimizing intermediate species and their adsorption behaviors toward CO2ER to ethanol.

Acidic open-cage solution containing basic cage-confined nanospaces for multipurpose catalysis.

The nanoscale chemical spaces inherent in porous organic/coordination cages or solid/liquid materials have been continuously explored for their nanoconfinement effect on selective adsorption and reaction of small gas or organic molecules. Herein, we aim to rationalize the unconventional chemical reactivities motivated by the cage-confined nanospaces in aqueous solutions, where the robust yet permeable nanospaces defined by the open cages facilitate dynamic guest exchange and unusual chemical reactions. The high positive charges on [(Pd/Pt)6(RuL3)8]28+ nanocages drive imidazole–proton equilibrium to display a significantly perturbed pKa shift, creating cage-defined nanospaces in solution with distinct intrinsic basicity and extrinsic acidity. The supramolecular cage effect plays pivotal roles in elaborating robust solution nanospaces, controlling ingress-and-egress molecular processes through open-cage portals and endowing nanocages with transition-state stabilization, amphoteric reactivities and the phase transfer of insoluble molecules, thus promoting chemical transformations in unconventional ways. Consequently, a wide range of application of cage-confined catalysis with anomalous reactivities may be expected based on this kind of open-cage solution medium, which combines cage nanocavity, solution heterogeneity and liquid-phase fluidity to benefit various potential mass transfer and molecular process options.

Molecular insights from theoretical calculations explain the differences in affinity and diffusion of airborne contaminants on surfaces of hBN and graphene

Exposed surfaces of two-dimensional (2D) materials are susceptible to the adsorption of various molecules including airborne contaminants, which can affect their performance in real applications. Hexagonal boron nitride (hBN) is structurally the closest relative to graphite and its single layer form to graphene. The adsorption of organic molecules to graphene was subject of extensive research, however, little is known about interaction ofadsorbates to hBN surface. We studied the affinity of organic molecules to the surface of hBN by inverse gas chromatography. The adsorption enthalpies of polar molecules including acetonitrile, nitromethane, ethanol, and acetone exhibited strong coverage dependency up to 20 % of a monolayer. Density functional theory and molecular dynamics calculations were employed to understand and interpret experimentally measured adsorption enthalpies. The calculations revealed that the strong affinity of polar molecules at low coverage was due to adsorption on steps and edges of hBN. The calculated surface diffusion barriers of all molecules were rather low, i.e., below 0.5 kcal/mol (except for benzene and cyclohexane), and molecules adsorbed on the surface behaved like a 2D gas. The results demonstrated that coupling inverse gas chromatography with computer simulations can provide vital insights into the mechanism of adsorption at the molecular level.

Spontaneous Adsorption-Induced Salvinia-like Micropillars with High Adhesion.

Superhydrophobic surfaces with high adhesion provide high potential for underwater applications. Inspired by Salvinia leaf, here, we have reported a simple method for fabricating adhesive Salvinia-like micropillars via photolithography and spontaneous adsorption of organic molecules from the atmosphere. With continuous hydrocarbon adsorption on sputtered cerium dioxide (CeO2) films, the surface gradually evolved and eventually became chemically heterogeneous. Huge wetting contrast from superhydrophilic to superhydrophobic over exposure time was observed; meanwhile, the wetting mode changed from the Wenzel (W) state to Cassie-Baxter (C-B) state. As a result, hydrophobic hydrocarbons (C-C/C-H) and trapped air between adjacent pillars contributed to the high apparent contact angle (CA), while the hydrophilic domains of C-O/O═C-O and CeO2 on the top layer made the surface highly adhesive with water droplets. In comparison with traditional fluorinated superhydrophobic surfaces, CeO2-coated surfaces showed high adhesive force with water droplets and can be used as a "mechanical hand" for water droplet transport. The adsorption-induced Salvinia-like micropillars with high adhesion may find many other droplet-based applications in microfluidic fields.