Vibration-driven Reduction of CO2 to Acetate with 100 % Selectivity by SnS Nanobelt Piezocatalysts

Converting CO₂ into high-value C2 chemicals such as acetate with high selectivity and efficiency is a critical issue in renewable energy storage. Herein, for the first time we present a vibration-driven piezocatalysis with tin(II) monosulfide (SnS) nanobelts for conversion of CO₂ to acetate with 100 % selectivity, and the highest production rate (2.21 mM h⁻¹) compared with reported catalysts. Mechanism analysis reveal that the polarized charges triggered by periodic mechanical vibration promote the adsorption and activation of CO₂. The electron transfer can be facilitated due to built-in electric field, decreased band gap and work function of SnS under stress. Remarkably, reduced distance between active sites leads to charge enrichment on Sn sites, promoting the C−C coupling, reducing the energy barriers of the rate determining step. It puts forward a bran-new strategy for converting CO₂ into high-value C2 products with efficient, low-cost and environment-friendly piezocatalysis utilizing mechanical energy.     

Construction of Asymmetrical Dual Jahn–Teller Sites for Photocatalytic CO2 Reduction

Photocatalytic CO₂ reduction (PCR) expresses great attraction to convert useless greenhouse gas into valuable chemical feedstock. However, the weak interactions between catalytic sites and PCR intermediates constrains the PCR activity and selectivity. Herein, we proposed a new strategy to match the intermediates due to the maximum orbital overlap of catalytic sites and C₁ intermediates by establishing dual Jahn–Teller (J–T) sites, in which, the strongly asymmetric J–T sites can break the nonpolar CO₂ molecules and self-adapt the different structure of C₁ intermediates. Taking cobalt carbonate hydroxide as an example, the weakly symmetric dual cobalt (Co₂) dual J–T sites, weakly asymmetric Fe&Co sites and strongly asymmetric Cu&Co sites were assembled. After illumination, the interaction between dual J–T sites and the CO₂ molecules enhances J–T distortion, which further modulates the PCR activity and selectivity. As a result, the Cu&Co sites exhibited CO yield of 8137.9 μmol g⁻¹, about 2.3-fold and 4.2-fold higher than that of the Fe&Co and Co₂ sites within 5-hour photoreaction, respectively. In addition, the selectivity achieved as high as 92.62 % than Fe&Co (88.67 %) and Co₂ sites (55.33 %). This work provides a novel design concept for the construction of dual J–T sites to regulate the catalytic activity and selectivity.     

Decrypting the Controlled Product Selectivity over Ag−Cu Bimetallic Surface Alloys for Electrochemical CO2 Reduction

Electrochemical CO₂ reduction reaction (ECO₂RR) with controlled product selectivity is realized on Ag−Cu bimetallic surface alloys, with high selectivity towards C2 hydrocarbons/alcohols (≈60 % faradaic efficiency, FE), C1 hydrocarbons/alcohols (≈41 % FE) and CO (≈74 % FE) achieved by tuning surface compositions and applied potentials. In situ spectral investigations and theoretical calculations reveal that surface-composition-dependent d-band center could tune *CO binding strengths, regulating the *CO subsequent reaction pathways and then the product selectivity. Further adjusting the applied potentials will alter the energy of participated electrons, which leads to controlled ECO₂RR selectivity towards desired products. A predominant region map, with an indicator proposed to evaluate the thermodynamic predominance of the *CO subsequent reactions, is then provided as a reliable theoretical guidance for the controllable ECO₂RR product selectivity over bimetallic alloys.     

Rational Synthesis of Amorphous Iron-Nickel Phosphonates for Highly Efficient Photocatalytic Water Oxidation with Almost 100 % Yield

A simple solvent ligation effect was successfully used to disrupt the growth of a model compound, Fe[(OH)(O₃P(CH₂)₂CO₂H)]⋅H₂O (MIL-37), into an extended 2D structure by replacing water with dimethylformamide (DMF) as the solvent during the synthesis. Owing to the lack of −OH group, which provides the corner-sharing (binding) oxygen atoms for the octahedra, an amorphous and porous structure is formed. When Fe³⁺ is partially replaced by Ni²⁺, the amorphous structure remains and the resultant binary metal catalyst displays excellent photocatalytic oxygen evolution activity with almost 100 % yield achieved under visible light irradiation using [Ru(bpy)₃]²⁺ as the photosensitizer. This study opens up new possibilities of using the simple solvent effect to synthesize high surface area metal phosphonates for catalytic and other applications.     

Investigation on Mechanism for Separation of Alkali, Alkaline Metal and Ammonium Cations in Nonaqueous Capillary Electrophoresis

Capillary electrophoresis ( CE ) has rapidly gained great interests among researchers in many different fields. One of these areas is the separation of small ions such as inorganic cations, anions, and low Mr organic molecules However, as the separation of ions     

Investigation on Mechanism for Separation of Alkali, Alkaline Metal and Ammonium Cations in Nonaqueous Capillary Electrophoresis

Capillary electrophoresis (CE )hasrapidlygainedgreatinterestsamongresearchersinmanydifferentfields .Oneoftheseareasistheseparationofsmallionssuchasinorganiccations[1- 9] ,an ions[10 - 16 ] ,andlowMr organicmolecules[17- 2 0 ] .However ,astheseparationofio…     

Formation of Hierarchical FeCoS2–CoS2 Double-Shelled Nanotubes with Enhanced Performance for Photocatalytic Reduction of CO2

Hierarchical FeCoS₂–CoS₂ double-shelled nanotubes have been rationally designed and constructed for efficient photocatalytic CO₂ reduction under visible light. The synthetic strategy, engaging the two-step cation-exchange reactions, precisely integrates two metal sulfides into a double-shelled tubular heterostructure with both of the shells assembled from ultrathin two-dimensional (2D) nanosheets. Benefiting from the distinctive structure and composition, the FeCoS₂–CoS₂ hybrid can reduce bulk-to-surface diffusion length of photoexcited charge carriers to facilitate their separation. Furthermore, this hybrid structure can expose abundant active sites for enhancing CO₂ adsorption and surface-dependent redox reactions, and harvest incident solar irradiation more efficiently by light scattering in the complex interior. As a result, these hierarchical FeCoS₂–CoS₂ double-shelled nanotubes exhibit superior activity and high stability for photosensitized deoxygenative CO₂ reduction, affording a high CO-generating rate of 28.1 μmol h⁻¹ (per 0.5 mg of catalyst).     

Photochemical In Situ Exfoliation of Metal–Organic Frameworks for Enhanced Visible-Light-Driven CO2 Reduction

Two novel two-dimensional metal–organic frameworks (2D MOFs), 2D-M₂TCPE (M=Co or Ni, TCPE=1,1,2,2-tetra(4-carboxylphenyl)ethylene), which are composed of staggered (4,4)-grid layers based on paddlewheel-shaped dimers, serve as heterogeneous photocatalysts for efficient reduction of CO₂ to CO. During the visible-light-driven catalysis, these structures undergo in situ exfoliation to form nanosheets, which exhibit excellent stability and improved catalytic activity. The exfoliated 2D-M₂TCPE nanosheets display a high CO evolution rate of 4174 μmol g⁻¹ h⁻¹ and high selectivity of 97.3 % for M=Co and Ni, and thus are superior to most reported MOFs. The performance differences and photocatalytic mechanisms have been studied with theoretical calculations and photoelectric experiments. This study provides new insight for the controllable synthesis of effective crystalline photocatalysts based on structural and morphological coregulation.     

Complexation of Calix[4]arene With Alkali Metal Cations: Conformational Binding Selectivity and Cation-π Driven Inclusion

Hartree-Fock, second order Møller-Plesset perturbation theory, and density functional theory calculations were carried out to analyse the complexation of calix[4]arene with cationic species including H + and the alkali metal cations (Li + , Na + , K + , Rb + , and Cs + ). Special emphasis has been placed on conformational binding selectivity, and on the structural characterization of the complexes. Li + and Na + cations are located in the calix[4]arene lower rim. The larger cations (K + , Rb + , and Cs + ) complex preferentially with the calix[4]arene cone conformer, and their endo (inclusive) complexation is driven by cation- ~ interactions, leading in the case of K + to a structure that reflects a preferential interaction with two phenol rings. The endo complexation of Cs + with calix[4]arene is in agreement with X-ray diffraction data.     

Single-Atom Electrocatalysts from Multivariate Metal–Organic Frameworks for Highly Selective Reduction of CO2 at Low Pressures

Single-atom catalysts (SACs) are of great interest because of their ultrahigh activity and selectivity. However, it is difficult to construct model SACs according to a general synthetic method, and therefore, discerning differences in activity of diverse single-atom catalysts is not straightforward. Herein, a general strategy for synthesis of single-atom metals implanted in N-doped carbon (M₁-N-C; M=Fe, Co, Ni and Cu) has been developed starting from multivariate metal–organic frameworks (MOFs). The M₁-N-C catalysts, featuring identical chemical environments and supports, provided an ideal platform for differentiating the activity of single-atom metal species. When employed in electrocatalytic CO₂ reduction, Ni₁-N-C exhibited a very high CO Faradaic efficiency (FE) up to 96.8 % that far surpassed Fe₁-, Co₁- and Cu₁-N-C. Remarkably, the best-performer, Ni₁-N-C, even demonstrated excellent CO FE at low CO₂ pressures, thereby representing a promising opportunity for the direct use of dilute CO₂ feedstock.     

The formation of formic acid upon low-temperature condensation of CO2−H2 and CO−H2O gas mixtures dissociated in electric discharge

The formation of formic acid in the low-temperature condensation of CO₂−H₂ and CO−H₂O gas mixtures dissociated in electric discharge was investigated. The gas-phase concentrations of H^., O^., OH^., and O₂ were measured downstream a microwave discharge in a CO₂−H₂ mixture. Low-temperature (77 K) condensates formed from CO₂−H₂ and CO−H₂O mixtures were studied by ESR. The formation of formic acid in the CO₂−H₂ and CO−H₂O systems was found to be due to the reactions of H^., CO, O^., and O₂ on the condensate surface. A single mechanism of the formation of formic acid in the CO₂−H₂ and CO−H₂O systems was proposed.     

Efficient and Direct Functionalization of Allylic sp3 C−H Bonds with Concomitant CO2 Reduction

Solar-driven CO₂ reduction integrated with C−C/C−X bond-forming organic synthesis represents a substantially untapped opportunity to simultaneously tackle carbon neutrality and create an atom-/redox-economical chemical synthesis. Herein, we demonstrate the first cooperative photoredox catalysis of efficient and tunable CO₂ reduction to syngas, paired with direct alkylation/arylation of unactivated allylic sp³ C−H bonds for accessing allylic C−C products, over SiO₂-supported single Ni atoms-decorated CdS quantum dots (QDs). Our protocol not only bypasses additional oxidant/reductant and pre-functionalization of organic substrates, affording a broad of allylic C−C products with moderate to excellent yields, but also produces syngas with tunable CO/H₂ ratios (1 : 2–5 : 1). Such win-win coupling catalysis highlights the high atom-, step- and redox-economy, and good durability, illuminating the tantalizing possibility of a renewable sunlight-driven chemical feedstocks manufacturing industry.     

Ph3P+CF2CO2− as an F− and :CF2 source for trifluoromethylthiolation of alkyl halides

Trifluoromethylthiolation of alkyl halides using Ph₃P⁺CF₂CO₂^- as a fluoride and difluorocarbene source is described. Even though the process involved a cleavage of a C-F bond and the formation of R-S, S C and C-F bonds, the reactions occurred rapidly and were completed within 10 min.     

Explicating the Role of Metal Centers in Porphyrin-Based MOFs of PCN-222（M） for Electrochemical Reduction of CO2

The porphyrin-based MOFs formed by combining Zr₆ clusters and porphyrin carboxylic acids with clear M-N₄ active centers show unique advantages in electrocatalytic reduction of CO₂（CO₂RR）. However, its conductivity is still the bottleneck that limits its catalytic activity due to the electrical insulation of the Zr cluster. Therefore, the porphyrin-based MOFs of PCN-222（M）(M = Mn, Co, Ni, Zn) with explicit M-N₄ coordination were combined with...     

What Role Does the Incident Light Intensity Play in Photocatalytic Conversion of CO2: Attenuation or Intensification?

Artificial photoreduction of CO₂ is vital for the sustainable development of human beings via solar energy storage in stable chemicals. This process involves intricate light-matter interactions, but the role of incident light intensity in photocatalysis remains obscure. Herein, the influence of excitation intensity on charge kinetics and photocatalytic activity is investigated. Model photocatalysts include the pure graphitic carbon nitride (g-C₃N₄) and g-C₃N₄ loaded with noble/non-noble-metal cocatalysts (Ag, TiN, and CuO). It is found that the increase of light intensity does not always improve the electron utilization. Overly high excitation intensities cause charge carrier congestion and changes the recombination mechanism, which is called the light congestion effect. The electron transport channels can be established to mitigate the light-induced effect via the addition of cocatalyst, leading to a nonlinear growth in the reaction rate with increasing light intensity. From experiments and simulations, it is found that the light intensity and active site density should be collectively optimized for increasing the energy conversion efficiency. This work elucidates the effect of light intensity on photocatalytic CO₂ reduction and emphasizes the synergistic relationship of matching the light intensity and the photocatalyst category. The study provides guidance for the design of efficient photocatalysts and the operation of photocatalytic systems.     

High-Valent Metal–Oxo Species at the Nodes of Metal–Triazolate Frameworks: The Effects of Ligand Exchange and Two-State Reactivity for C−H Bond Activation

Through quantum-chemical calculations, we investigate a family of metal–organic frameworks (MOFs) containing triazolate linkers, M₂X₂(BBTA) (M=metal, X=bridging anion, H₂BBTA=1H,5H-benzo(1,2-d:4,5-d′)bistriazole), for their ability to form terminal metal–oxo sites and subsequently activate the C−H bond of methane. By varying the metal and bridging anion in the framework, we show how to significantly tune the reactivity of this series of MOFs. The electronic structure of the metal–oxo active site is analyzed for each combination of metal and bridging ligand, and we find that spin density localized on the oxo ligand is not an inherent requirement for low C−H activation barriers. For the Mn- and Fe-containing frameworks, a transition from ferromagnetic to antiferromagnetic coupling between the metal binding site and terminal oxo ligand during the C−H activation process can greatly reduce the kinetic barrier, a unique case of two-state reactivity without a change in the net spin multiplicity.     

The π-hole tetrel bond between X2TO and CO2: Substituent effects and its potential adsorptivity for CO2

Quantum chemical calculations are applied to study the complexes between X₂TO (X = H, F, Cl, Br, CH₃; T = C, Si, Ge, Sn) and CO₂. The carbon atom of CO₂ as a Lewis acid participates in the C···O carbon bond, whereas its oxygen atom as a base engages in the O···T tetrel bond with X₂TO. Most of complexes are stabilized by a combination of both C···O and O···T interactions. The interaction energy increases in the T = C < Ge < Sn < Si sequence for most complexes. Both the electron-withdrawing halogen group and the electron-donating methyl group increase the interaction energy, up to 51 kJ/mol in F₂SiO···CO₂. One F₂SiO molecule can bind with different numbers of CO₂ molecules (1–4); as the number of CO₂ molecules increases, the average interaction energy for each CO₂ decreases and each CO₂ molecule can contribute with at least 27 kJ/mol. Therefore, silicon-containing molecules are good absorbents for CO₂.     

Metal–Organic Frameworks and Other Crystalline Materials for Ultrahigh Superprotonic Conductivities of 10−2 S cm−1 or Higher

Proton-conducting materials in the solid state have received immense attention for their role as electrolytes in proton-exchange membrane fuel cells. Recently, crystalline materials—metal–organic frameworks (MOFs), hydrogen-bonded organic frameworks (HOFs), covalent organic frameworks (COFs), polyoxometalates (POMs), and porous organic crystals—have become an exciting research topic in the field of proton-conducting materials. For a better electrolyte, a high proton conductivity on the order of 10⁻² S cm⁻¹ or higher is preferred as efficient proton transport between the electrodes is ultimately necessary. With an emphasis on design principles, this Concept will focus on MOFs and other crystalline solid-based proton-conducting platforms that exhibit “ultrahigh superprotonic” conductivities with values in excess of 10⁻² S cm⁻¹. While only a handful of MOFs exhibit such an ultrahigh conductivity, this quality in other systems is even rarer. In addition to interpreting the structural–functional correlation by taking advantage of their crystalline nature, we address the challenges and promising directions for future research.     

Retracted: The Effect of Air on the Oxidation Decomposition of Cationic Exchange Resins in a Ternary Li2CO3−Na2CO3−K2CO3 Molten-Salt System

The molten-salt oxidation method (MSO) can be applied for disposal of spent cationic exchange resins (CERs) after the treatment of nuclear industry wastewater. In this work, the oxidation decomposition of resins in carbonate molten salt in N₂ and air atmospheres was investigated. The SEM morphology and FTIR spectrograms indicated that the addition of air obviously prompted the oxidation decomposition of the benzene ring, S−O bond and S−C bond in residues and the decomposition efficiency of resins reached 98.69 % at 800 °C. The XPS analysis showed the conversion of sulfur species in residues. The peroxide and superoxide ions in carbonate molten salt prompted the decomposition of thiophene sulfur and resulted in the formation of sulfate. The retention rate of sulfur in spent salt was 84.36 % at 800 °C. This work provided more theoretical guidance for the treatment of resins and technical support for the sustainable development of nuclear industry.