Electron-rich Surface Research Articles

Surface curvature-driven adsorption-reduction mechanism over hollow N-doped carbon enhances recovery of precious metal ions from wastewater.

The recovery of precious metal ions (PMI) from wastewater has great significances from both economic and environmental perspectives. However, current recovery methods face limitations, including low efficiency and selectivity, as well as challenges in practical applications. In this study, hollow N-doped carbon spheres (HNC) are proved to be promising for improving anionic AuCl4- and PdCl42- recovery via the curvature effect, outperforming non-curved carbon (commercial active carbon and carbon nanosheet) due to their unique curvature effect. The maximum recovery capacities of HNC for AuCl4- and PdCl42- reach as high as 304.90 mg·g -1 and 84.31 mg·g -1 (calculated as metallic elements), far exceeding those of activated carbon (175.9 mg·g -1 for Au and 46.87 mg·g -1 for Pd) and carbon nanosheet (33.92 mg·g -1 for Au and 4.33 mg·g -1 for Pd). The recovery processes of HNC could reach equilibrium within 1 h, exhibiting a rapid recovery kinetic process. The superior recovery performance of HNC can be attributed to the adsorption-reduction mechanism. The convex surface of HNC concentrates a lot of electrons due to the curvature effect, facilitating the electron transfer from HNC to PMI. The key reduction process is thus induced on the electron-rich outer surface of the sphere. Remarkably, the increased curvatures significantly boost the PMI recovery, further confirming the importance of curvature effect. In addition, HNC materials exhibit superior anti-interference ability against co-existing ions and potential practicability. Therefore, innovative adsorption-reduction mechanism and curvature effect are proposed, which offer a new prospect in developing cost-effective recovery technology of precious metals and environmental remediation.

Highly Tension-Strained Copper Concentrates Diluted Cations for Selective Proton-Exchange Membrane CO2 Electrolysis.

Electrolysis of carbon dioxide (CO2) in acid offers a promising route to overcome CO2 loss in alkaline and neutral electrolytes, but requires concentrated alkali cations (typical ≥3 M) to mitigate the trade-off between low pH and high hydrogen evolution reaction (HER) rate, causing salt precipitation. Here we report a strategy to resolve this problem by introducing tensile strain in a copper (Cu) catalyst, which can selectively reduce CO2 to valuable multicarbon products, particularly ethylene, in a pH 1 electrolyte with 1 M potassium ions. We find that the tension-strained Cu creates an electron-rich surface that concentrates diluted potassium ions, contributing to CO2 activation and HER suppression. With this catalyst, we show constant ethylene Faradaic efficiency (FE) of 44.3% over 100 hours at 400 mA cm-2 and a cell voltage of 3.1 volts in a proton-exchange membrane electrolyser. Moreover, selective electrosynthesis of ethylene oxide using the as-produced ethylene was demonstrated in an integrated system.

Direct synthesis of PtNi coated with Ni3B for efficient electrochemical hydrogen evolution from seawater.

The design of a protective electron-rich surface is an ideal route to enhance the performance of catalysts. Due to the higher work function of Ni3B, facile-directed electron transport occurs from PtNi to Ni3B to enrich electron density on the surface of the Ni3B shell. This process increases hydrogen adsorption-desorption kinetics and mitigates Cl- corrosion.

Surface chemical and electronic properties of functionalized Fe3O4 nanoparticles influencing their cytotoxicity

Physico-chemical, electronic and magnetic properties of bare Fe3O4 nanoparticles (NPs) and functionalized NPs (f-NPs) with doxorubicin, tannic acid, curcumin, polyethylene glycol and their mixtures were determined using DLS, XRD, XPS and AES. The cytotoxicity of bare and f-NPs for various cell lines such as normal HEK-293 and cancer HeLa, MDA-MB-231, and MCF-7 was studied by MTT (3–(4,5–Dimethylthiazol–2–yl)–2,5–Diphenyltetrazolium Bromide) assay. Bare and f-NPs exhibited different cytotoxicity dependent on molecules bonding at the surface. Cytotoxicity increases with decreasing hydrodynamic diameter and increasing Zeta potential, increasing content of lattice and adsorbed O2−, carboxyl groups and C vacancies, NH4+ groups, decreasing overlayer thickness, electron charge transfer to oxygen and more nucleophilic character of electron rich surface oxygen. The strongest correlation was observed for hydrodynamic diameter, Fe surface content, overlayer thickness, Zeta-potential, Auger parameters indicating that surface processes and electron charge transfer leading to nucleophilic oxygen contribute mostly to cytotoxicity. Nucleophilic biomolecules may form a variety of covalent modifications with electrophilic adducts and hydrogen bonds with nucleophiles and the suspected predominant mechanism of biomolecule damage can be attributed to electron rich nucleophilic oxygen leading to a very selective C–H bonds cleavage resulting in oxidation of organic chains of biomolecule.

Size-Dependent Copper Nanoparticles Supported on Carbon Nanotubes with Balanced Cu+ and Cu0 Dual Sites for the Selective Hydrogenation of Ethylene Carbonate.

Cyclic carbonate hydrogenation offers an alternative for the efficient indirect CO2 utilization. In this study, a series of carbon nanotubes (CNTs) supported xCu/CNTs catalysts with different Cu loadings were fabricated using a convenient impregnation method, and exhibited excellent catalytic activity for the hydrogenation of ethylene carbonate to methanol and ethylene glycol. The structural and physicochemical properties revealed that acid treatment of CNTs resulted in plentiful oxygen-containing functional groups, providing sufficient anchoring sites for copper species. The calcination process conducted under an inert atmosphere resulted in the formation of ternary CuO, Cu2O, and Cu composites, enhancing the metal-support interaction and facilitating the formation of balanced Cu0 and Cu+ dual sites as well as high active surface area after reduction. Contributed to the synergetic effect of balanced Cu+ and Cu0 species proved by density functional theory calculation and the electron-rich CNTs surface, the 40Cu/CNTs catalyst achieved strengthened catalytic performance with methanol yield of 83 %, ethylene glycol yield of 99 % at ethylene carbonate conversion of >99 %, and 150 h of long-term running stability. Consequently, CNTs supported Cu serve as efficient non-silica based catalyst for ester hydrogenation.

Alkali metal cation adsorption–induced surface polarization in polymeric carbon nitride for enhanced photocatalytic hydrogen peroxide production

Photocatalytic hydrogen peroxide (H2O2) generation on the catalyst surface from oxygen is an electron-demanding process, making the construction of an electron-rich surface highly advantageous. In this study, a localized electric field was observed on the surface of polymeric carbon nitride (g-C3N4) when alkali metal cations were adsorbed onto it. These fields effectively inhibited surface carrier recombination and extended their lifespan, thereby enhancing H2O2 production. As a result, g-C3N4 achieved a superior H2O2 yield of 2.25 mM after 1 h in a 0.25 M K+ solution, which was 2.06 times greater than that (1.09 mM) achieved in a pure solvent. Notably, the increase in photocatalytic efficiency showed a remarkable dependence on ion species. At low concentrations, H2O2 generation efficiency was in the order of Li+ < Na+ < K+ < Rb+ < Cs+. However, after optimizing the ion concentration, the highest H2O2 production was achieved in a solution containing K+ instead of Cs+. Molecular dynamics simulations and temperature-dependent photocatalysis experiments revealed that the synergistic interaction between adsorption energy and adsorption distance was crucial in governing the extent to which alkali metal cation adsorption enhanced g-C3N4 photocatalytic H2O2 production. This study provides theoretical insights for the design of materials for electron-demanding photocatalysis and aids in understanding variations in photocatalytic behavior in natural waters.

Enhanced paracetamol degradation via strong covalent coupling of Mo[sbnd]O[sbnd]C bonds in C/MoS2 nanocomposites for piezoelectric activation of peroxymonosulfate: Electron bridge and enrichment

Paracetamol (PCM) has been frequently detected in natural water bodies, posing potential threats to human health and the natural environment. In this work, we developed a strong covalent coupling system of MoOC within carbon doped MoS2 (C/MoS2) material to piezoelectrically activate peroxymonosulfate (PMS) for PCM degradation. The C/MoS2 was synthesized successfully using one-step hydrothermal method and exhibited 91.8 % of PCM degradation efficiency and 0.04042 min−1 of rate constant (3.29 times of pristine MoS2) within 60 min under ultrasonic vibration. According to characterization and theoretical computational results, the Mo atoms near sulfur vacancies exhibited unsaturation, enabling them to bond with oxygen atoms on carbon substrate, forming a strong covalent coupling structure primarily driven by MoOC bonds. MoOC bonds served as “electron bridges” that efficiently transported electrons from the piezoelectrically excited electron reservoir of MoS2 to the active sites at heterogeneous interfaces, creating electron-rich surface regions and simultaneously inhibiting the recombination of piezoelectric charge carriers, thereby essentially enhancing the intrinsic conductivity of MoS2. Furthermore, as active adsorption sites, MoOC bonds initially strongly adsorbed PMS, activating it into reactive oxygen species (ROS), subsequently absorbing O2 to realize the enrichment of oxides and further promote the PCM decomposition. This work offered new perspectives on the interface modification and development of efficient MoS2-based piezoelectric catalysts for water purification.

Sabatier phenomenon in chemoselective gas-sensing reactions induced by Ag cluster coordination

The Sabatier principle in heterogeneous catalysis provides guidance for designing optimal catalysts with the highest activity. We report a new Sabatier phenomenon induced by nanoclusters on different atomic scales in gas-sensitive reactions. We prepared a series of Ag nanocluster catalysts with coordination structures ranging from Ag0 to Ag13 through a surface coordination strategy. When used as catalysts for gas-sensitive reactions, a volcano-type relationship between the coordination number of Ag nanoclusters and gas-sensitive activity emerges, with a summit at a moderate coordination of Ag5. Mechanistic studies show that the efficient adsorption of activated *C2H6O on electron-rich Ag5 clusters is a key factor for the Sabatier phenomenon (adsorption energy from −0.322 eV to −0.663 eV), which leads to highly selective sensing. We found that the catalyst electron-rich surface layer induced by Ag5 clusters serves as a descriptor to explain the structure–activity relationship. Furthermore, due to the well-defined geometric and electronic structures in the Ag5 clusters, the optimized catalyst achieves both maximum activity and selectivity in chemoselective sensing reactions. This study reveals the Sabatier principle and provides insightful guidance for the rational design of more efficient and practical nanocluster catalysts for heterogeneous catalysis.

Engineering an organic electron-rich surface passivation layer for efficient and stable perovskite solar cells

Engineering an organic electron-rich surface passivation layer for efficient and stable perovskite solar cells

0D/2D Bi2MoO6 quantum dots /rGO heterojunction boosting full solar spectrum-driven photothermal catalytic CO2 reduction to solar fuels

The photothermal-catalyzed CO2 reduction is severely limited by the low carrier transport capacity. In this paper, the in-situ construction of 0D/2D Bi2MoO6 (BMO)/reduced Graphene Oxide (rGO) heterojunction was synthesized. The excellent photothermal conversion ability of rGO promotes the high dispersion of BMO quantum dots (QDs). The size of synthesized BMO QDs is about 4.26 nm and the temperature of the catalysts can quickly rise to 68.0 °C. XPS results show that the C–O–Bi interfacial electronic bridge between surface oxygen-containing groups and BMO QDs was successfully induced by modulating the degree of GO reduction. Electrons generated by BMO QDs migrate to the rGO surface rapidly, inducing rGO as a new electron-rich surface for rapid activation of CO2. The 1:5 BMO/rGO (NaBH4) CO yield reaches 186.87 μmol/g, which is 4.64 times as much as BMO QDs.

Affinity Measurement of Non-covalent Interactions of the Covalent KRAS G12C GDP Inhibitor MRTX849 to RAS Isoforms Using Surface Plasmon Resonance.

Surface plasmon resonance (SPR) is an optical effect at an electron-rich surface that enables affinity measurements of biomolecules in real time. It is label free and versatile, not limited to proteins, nucleic acids, and small molecules. SPR is a widely accepted method to measure not only affinity of molecular interactions but also association and dissociation rates of such interactions. In this chapter, we describe a general method to measure the affinity of a small molecule drug, MRTX849, to GDP bound HRAS, KRAS, and NRAS.

Tuning the electronic structure of Pd by the surface configuration of Al2O3 for hydrogenation reactions.

The electronic interaction between a metal and a support modulates the electronic structures of supported metals and plays an important role in manipulating their catalytic performance. However, this interaction is mainly realized in heterogeneous catalysts composed of reducible oxides. Herein, we demonstrate the electronic interaction between γ-Al2O3 and η-Al2O3 with varying acid-base properties and supported Pd nanoparticles (NPs) of 2 nm in size. The strength and number of acid-base sites on the supports and catalysts were systemically characterized by FT-IR spectroscopy and TPD. The supported Pd NPs exhibit electron-rich surface properties by receiving electrons from the electron-donating basic sites on γ-Al2O3, which are beneficial for catalyzing the hydrogenation of nitrobenzene. In contrast, Pd NPs loaded on η-Al2O3 are electron-deficient because of the rich electron-withdrawing acid sites of η-Al2O3. As a result, Pd/η-Al2O3 exhibits higher catalytic activity in phenylacetylene hydrogenation than Pd/γ-Al2O3. Our results suggest a promising route for designing high-performance catalysts by adjusting the acid-base properties of Al2O3 supports to maneuver the electronic structures of metals.

N-Doped Norbornane sp2 Carbon Framework: An Efficient Electrocatalyst for Oxygen Reduction and Hydrogen Evolution Reaction

At present, development of Pt free bifunctional electrocatalyst for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) is necessary for the advancement of sustainable and cost-effective solutions for energy conversion and storage technology. In this direction, herein we report N doped sp2 hybridized carbon framework (N-CF) as a metal-free electrocatalyst for ORR and HER. This work inspects the effect of N doping that converts a hybrid structure of CF {Norbornane or bicyclo [2, 2, 1] heptane structure} into planar N-CF. A series of N-doped CF with different doping concentrations has been prepared using a facile and cost-effective technique. This robust electrocatalysts exhibits a promotional effect in the activity, porosity, thermal and electrochemical stability for the ORR and HER reactions. A rich delocalized electronic density of the sp2 bounded N species helps in modulating antibonding state of molecular oxygen and facilitates the breakage of O=O bond in ORR. It also promotes proton adsorption via bonding between proton and valence electron rich catalyst surface to aid HER. The research sought to investigate the employability of N-CF for fabricating sustainable energy devices with electrocatalyst possessing multiple electrocatalytic activities for ORR and HER. Figure 1

Fabrication of single Co sites in graphitic carbon nitride via the ion exchange to boost aerobic cyclohexane oxidation

Cyclohexane oxidation is an industrial process for manufacturing cyclohexanol, cyclohexanone and adipic acid, while it remains a huge challenge to develop highly efficient catalysts for intensifying this process. Herein, a bottom-up synthesis approach, coupling the one-pot and ion exchange strategy, is developed to fabricate atomically dispersed Co on graphitic carbon nitride (g-C3N4) for the aerobic cyclohexane oxidation. The loading of the single-atom Co on Co/g-C3N4 can be facilely tuned by adjusting the ion exchange extent of Na + on Na/g-C3N4 precursor. Comprehensive characterizations demonstrate the atomical location of Co in sixfold cavities of g-C3N4, accompanied by the electron interaction between Co atoms and g-C3N4. The resulting Co/g–C3N4–1 catalyst possesses the superior oxidation performance with the 28.8 % cyclohexane conversion and 93.0 % overall selectivity toward desired products, and it also exhibits an acceptable universality to the catalytic oxidation of various hydrocarbons. The mechanism study revealed that besides the dissociation of O2 molecules on single-atom Co sites, the electron-rich g-C3N4 surface stemming from atomic Co doping facilitated the cyclohexane adsorption, which synergically boosted the subsequent oxidation reaction following the surface catalytic mechanism. We anticipate that such a concept of fabricating atomically dispersed metals via the ion exchange strategy provides a novel insight and feasible approach for the design of highly efficient single-atom catalysts for the cyclohexane oxidation and beyond.

Discovery of Small‐Molecule Inhibitors Targeting Progranulin‐Sortilin: An in‐silico Approach Using Molecular Docking, Molecular Dynamics Simulations, and DFT Studies

AbstractIntroduction: Reduction in progranulin (PGRN) have been associated with various neurodegenerative diseases. PGRN binds with high affinity to sortilin (SORT), a membrane transporter, resulting in its cellular uptake and eventual degradation in the lysosome. Inhibition of the SORT‐PGRN interaction has the potential to increase PGRN levels up to 2.5‐fold. Methodology: A virtual screening of curated CNS library of &gt;47 K ligands was done with sortilin receptor (6X3L) through virtual screening workflow in Schrodinger suite. Co‐crystallised ligand was used as a positive control. Docking was done through HTVS, then SP and finally XP model followed by binding free energy calculations (MMGBSA). Based on the result analysis of molecular docking, binding free energy and interactions, docked complexes were chosen for molecular dynamics (MD) studies. DFT studies and MEP plotting were carried out for the screened ligands. Drug likeliness and ADMET studies were also carried out. Results: The virtual screening workflow yielded 139 ligands. Two test ligands and a control were selected and further evaluated through molecular dynamics studies. Both the test ligands (1625 &amp; 127) had comparative docking score (−5.96 &amp; −6.46 kcal/mol) as that of control ligand (−6.21 kcal/mol respectively) and but better binding free energy (−54.66, −53.12 &amp; −43.21 kcal/mol respectively). MD simulations confirmed the docking results for all the three ligands where our test ligand 1625 reached equilibrium quickly as compared to the rest. Our test compounds also showed favourable characteristics of a CNS acting drug and favourable ADMET properties. According to DFT studies, the test ligands 127 and 1625 had FMO (HOMO‐LUMO) energy gaps of 8.86 eV and 9.83 eV, respectively, that were lesser than the control ligand (9.89 eV). Additionally, FMO energy gap of the test ligands and the control ligand were in agreement with the results of docking. MEP diagram provided the picture of electron rich, neutral and electron deficient surface of the test ligands and that of the control with respective color code red, green and blue. Conclusion: Our study results showed a promising CNS specific ligand as an inhibitor of PRGN‐SORT interactions and has a potential to be developed as a drug through in‐vitro and in‐vivo studies.

Understanding CO2 reduction via reverse water-gas shift triggered by electromagnetic induction at moderate condition

Electromagnetic induction heating (EMIH) boosted highly selective reduction of CO2 into CO on Fe fiber-based catalysts, via reverse water–gas shift (RWGS) proceeding at milder condition than traditional heating. Doping Ru promoted catalytic performance, and among them the optimal content of nominal Ru loading was 3 %. In system of EMIH-driven RWGS on 3 %Ru/Fe, the demanded temperature of reaction bed for about 40 % CO2 conversion decreased by 100 °C compared to traditional heating-driven RWGS. By employing in-situ characterizations configured with EMIH module, it was found that the alternating electromagnetic field deflected EMIH-induced current eddy causing electron enrichment on surface of catalyst. On the electron-rich surface of catalyst, RWGS reaction driven by EMIH obeyed HCOOH-intermediated mechanism, which faced lower energy barriers than the redox pathway underwent by traditional heating driven-RWGS.

Bridging Effect of Carbon Nitride with More Negative Conduction Potential and Halogens Promotes the Liquid-Phase Oxidation of Aromatic C-H Bonds.

The selective oxidation of benzyl C-H bonds of alkyl aromatic hydrocarbons under solvent-free conditions by using heterogeneous catalysis is a challenging task. In this work, we designed a carbon nitride photocatalyst with a high charge separation efficiency and a directed charge transfer path, which was doped with Ni and Br in the carbon nitride skeleton. Br was deposited directionally onto the electron-rich Ni surface traps to form a bond with Ni, which acted as a charge transfer bridge connecting CN and Br, resulting in a bridging effect. Photogenerated electrons were transferred from Ni target to Br, and electrons were aggregated to form a directional charge transfer path, thereby enhancing the photocatalytic performance of CN. The photocatalyst was utilized for the selective oxidation of ethylbenzene at room temperature, atmospheric pressure, and solvent-free conditions. Under batch conditions simulating solar irradiation, the conversion of ethylbenzene was 43.3% and the selectivity of the product acetophenone was up to 92.0%. With the continuous flow strategy, the conversion of ethylbenzene was increased to 52.4 and 48.1%, respectively, while the selectivity reached 92.7 and 91.0%, and the reaction time was reduced from 24 to 2.1 h. The catalyst was also found to be broadly applicable for the selective oxidation of C-H bonds in the benzyl position of alkyl aromatic hydrocarbons.

Engineering iron carbide catalyst with aerophilic and electron-rich surface for improved electrochemical CO2 reduction

Highly efficient electrocatalyst for carbon dioxide reduction (CO2RR) is desirable for converting CO2 into carbon-based chemicals and reducing anthropogenic carbon emission. Regulating catalyst surface to improve the affinity for CO2 and the capability of CO2 activation is the key to high-efficiency CO2RR. In this work, we develop an iron carbide catalyst encapsulated in nitrogenated carbon (SeN-Fe3C) with an aerophilic and electron-rich surface by inducing preferential formation of pyridinic-N species and engineering more negatively charged Fe sites. The SeN-Fe3C exhibits an excellent CO selectivity with a CO Faradaic efficiency (FE) of 92 % at −0.5 V (vs. RHE) and remarkably enhanced CO partial current density as compared to the N-Fe3C catalyst. Our results demonstrate that Se doping reduces the Fe3C particle size and improves the dispersion of Fe3C on nitrogenated carbon. More importantly, the preferential formation of pyridinic-N species induced by Se doping endows the SeN-Fe3C with an aerophilic surface and improves the affinity of the SeN-Fe3C for CO2. Density functional theory (DFT) calculations reveal that the electron-rich surface, which is caused by pyridinic N species and much more negatively charged Fe sites, leads to a high degree of polarization and activation of CO2 molecule, thus conferring a remarkably improved CO2RR activity on the SeN-Fe3C catalyst.

Enhancing electrocatalytic methanol oxidation of Pd-Ir nanoalloy through electron-rich catalytic interface induced by incorporating phosphorus

Incorporating less expensive nonmetal phosphorus (P) into noble metal-based catalysts has become a developing strategy to enhance the catalytic performance of electrocatalysts for methanol electrooxidation reaction (MOR), attributing to the electronic and synergistic structure alteration mechanism. In the work, three-dimensional nitrogen-doped graphene anchoring ternary Pd-Ir-P nanoalloy catalyst (Pd7IrPx/NG) was prepared by co-reduction strategy. As a multi-electron system, elemental P adjusts the outer electron structure of Pd and diminishes the particle size of nanocomposites, which heightens the electrocatalytic activity effectively and accelerate MOR kinetics in alkaline medium. The study reveals that the electron effect and ligand effect induced by P atoms on the hydrophilic and electron-rich surface of Pd7Ir/NG and Pd7IrPx/NG samples can reduce the initial oxidation potential and peak potential of COads, showing significantly enhanced the anti-poisoning ability compared with commercial Pd/C as the benchmark. Meanwhile, the stability of Pd7IrPx/NG is significantly higher than that of commercial Pd/C. The facile synthetic approach provides an economic option and a new vision for the development of electrocatalysts in MOR.

Tailored synthesis of a palladium catalyst supported on nitrogen-doped carbon nanotubes for gas-phase formic acid decomposition: A strong influence of a way of nitrogen doping

Palladium catalysts supported on different nitrogen-containing carbon nanotubes (N-CNTs) were successfully used in the continuous gas-phase formic acid decomposition for hydrogen production. A strong influence of a way of carbon tubes doping by nitrogen on the activity of catalysts comprising metallic nanoparticles of ca. 1 nm in size and single-atom Pd2+ species was found. A key role of the single-atom species, demonstrating excellent stability in various chemically aggressive media, in the catalyst activity was discovered when bamboo-like N-CNTs synthesized by catalytic chemical vapor deposition were used as a support. A substantial increase in the activity of Pd nanoparticles was achieved by the use of N-СNTs prepared by the post-treatment of oxidized multiwalled carbon nanotubes by ammonia resulting in the formation of the dominating surface amine groups. The combination of the electron-rich palladium nanoparticles and surface amine groups leads to an increase in the TOF value by a factor of 7 at 70 °C. The catalyst operates stable at >99 % selectivity to hydrogen with the mass specific performance 200 l H2/gPd ⋅ h.