Latest ArticlesDeuterated ethylene is an important building block for manufacturing various deuterated polyolefins and chemicals. However, low-cost and large-scale production of deuterated ethylene still remain a great challenge. Herein, with D2O as the D source, we first propose an electrocatalytic deuteration strategy for continuous production of deuterated ethylene from acetylene under ambient conditions. Specially, Ag nanoparticles exhibit a very high deuterated ethylene Faradic efficiency of up to 99.3% at –0.6 V vs. reversible hydrogen electrode. Meanwhile, Ag nanoparticles achieve a deuterated ethylene production rate of 3.72 × 103 mmol h–1 gcat–1 and an excellent long-term stability with deuterated ethylene Faradaic efficiencies of ~95% in a two-electrode flow cell, which substantially outperform state-of-the-art values for previously reported deuterated alkenes. In-situ electrochemical Infrared absorption and Raman spectroscopies reveal superior acetylene absorption and formation of deuterated ethylene on Ag nanoparticles. This efficient electrocatalytic deuteration strategy opens a new window for continuous and economic production of deuterated alkenes.
Owing to its outstanding photoactivity, ferrioxalate is originally used as an actinometer and subsequent work has discovered that photochemistry of ferrioxalate is also fundamentally or technically important in atmospheric chemistry and water treatment. While the overall products generated from photolysis of ferrioxalate are known to include Fe(Ⅱ), a series of oxidizing (e.g., •OH, O2•−/HO2•−) or reducing (C2O4•−/CO2•−) radicals and H2O2, however, at the molecular level, the primary step of the photoreaction of ferrioxalate remains as an unsolved mystery due to the difficulty in examining such ultrafast processes. Benefiting from the development of time-resolved spectroscopy, this old question has been studied with increasing vigor recently, by means of such ever-more-sophisticated techniques (e.g., flash photolysis, time-resolved X-ray absorption spectroscopy (XAS), femtosecond infrared (IR) absorption spectroscopy, ultrafast photoelectron spectroscopy (PES)). There are two contrary views on the primary reaction mechanism: (1) Intramolecular electron transfer (ET) precedes the cleavage of the metal-ligand bond; (2) The dissociation of C–C or Fe–O bond occurs before intramolecular ET. Thus, this review presents a comprehensive summary about the overall reaction mechanism and molecular level mechanism of ferrioxalates. In chronological order, we have elaborated two predominant but controversial views from the perspectives of different experimental approaches. Some challenges and research opportunities in this active field are also briefly discussed.
Exploring remarkable oxygen reduction reaction (ORR) electrocatalysts for regenerative fuel cells and metal-air batteries is highly essential. Herein, a novel non-noble metal-based heterogeneous electrocatalyst with rich defects were successfully synthesized by liquid-liquid interfacial precipitation (LLIP) of fullerene (C60) and ferrotetraphenylporphyrin (FeTPP) followed by one step pyrolysis. The obtained product annealed at 700 ℃ (C60/FeTPP-700), when employed as ORR electrocatalyst, revealed a positive half-wave potential (E1/2) of 0.877 V vs. reversible hydrogen electrode (RHE), which was superior to that of the commercial 25% Pt/C. Delightfully, the assembled Zn-air battery (ZAB) using C60/FeTPP-700 as an air-electrode catalyst exhibited a high power density of 153 mW/cm2, specific capacity of 668 mAh/g and long-term cycling stability for more than 250 h. Experimental results proved that the excellent electrocatalytic ORR activity of C60/FeTPP-700 would attribute to the synergistic effect between FeNx sites, Fe3C/Fe nanoparticles and the structure defects. This work provides a feasible and simple method to prepare non-noble metal-based ORR electrocatalysts for the application of energy storage and conversion.
Benzimidazoles are very important chemical materials in the pharmaceutical industry, and the most common synthetic route is cyclization of o-phenylenediamine with carbon sources, in which utilization of inexpensive and abundant CO2 as C1 source is very impressive. Porous aromatic frameworks (PAFs) with highly desired skeletons have attracted great attentions in gas capture and catalysis. Herein, B-based PAF-165 and PAF-166 are designed and synthesized via Friedel-Crafts alkylation reaction, which present high surface areas as well as high stability. Benefiting from the abundant electron-deficient B centers, both PAFs exhibit excellent selective CO2 adsorption abilities. The presence of sterically hindered B units in PAFs can act as Lewis acid active sites for the frustrated Lewis pairs (FLPs) in situ formation with o-phenylenediamine, thus promoting the synthesis of benzimidazole. The optimal reaction conditions for o-phenylenediamine cyclization with PAF catalysts are explored, and the reaction mechanism is also proposed. This work provides feasible ideas for incorporating FLPs within porous materials as reusable heterogeneous catalysts for CO2 capture and conversion.
The dioxygen activation catalyzed by 4-hydorxylphenyl pyruvate dioxygenase (HPPD) were reinvestigated by using hybrid quantum mechanics/molecular mechanics (QM/MM) approaches at the B3LYP/6-311++G(d, p): AMBER level. These studies showed that this reaction consisted of two steps including the dioxygen addition/decarboxylation and hetero OO bond cleavage, where the first step was found to be rate-determining. The former step initially runs on a septet potential energy surface (PES), then switches to a quintet PES after crossing a septet/quintet minimum energy crossing point (MECP) 5-7M2, whereas the rest step runs on the quintet PES. The reliability of our theoretical predictions is supported by the excellent agreement of the calculated free-energy barrier value of 16.9 kcal/mol with available experimental value of 16–17 kcal/mol. The present study challenges the widely accepted view which holds that the O2 activation catalyzed by α-keto glutamate (α-KG) dioxygenase mainly runs on the quintet PES and provides new insight into the catalytic mechanism of α-KG dioxygenase and/or other related Fe(Ⅱ)-dependent oxygenase.
Ultra-low dielectric loss (Df) and low dielectric constant (Dk) materials are urgently required in high-speed and large-capacity transmission, in which the wholly aromatic liquid crystal polymer (LCP) has gained attention due to its excellent dielectric properties. However, the relationship between molecular structure and dielectric properties is still not clear. In this study, two copolyesters containing phenyl or naphthyl structures are synthesized, as well as the effects of benzene and naphthalene mesogens on dielectric properties are investigated. The synthesized copolyesters containing naphthalene structure have good comprehensive properties with high thermal stability (T5% = 479 ℃ and Tg = 195–216 ℃), inherent flame retardance (LOI = 33.0–35.0 and UL-94 V-0 level at 0.8 mm), low Dk (2.9–3.0@10 GHz) and low Df (0.0027–0.0047@10 GHz). Naphthalene mesogen can reduce the dielectric loss more significantly than benzene at high frequency by reducing the density and mobility of polarizable groups, which leads to the effectively limited dipole polarization in copolyesters. Consequently, we proposed a new strategy for designing low Dk and low Df materials.
Design of electrochemical active boron (B) site at solid materials to understand the relationships between the localized structure, charge state at the B site and electrocatalytic activity plays a crucial role in boosting the green electrochemical synthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction (2eORR) pathway. Herein, we demonstrate a carbon (C) and nitrogen (N) localized bonding microenvironment to modulate the charge state of B site at the boron-carbon nitride solid (BCNs) to realize the efficient selective electrocatalytic H2O2 production. The localized chemical structure of N-B-N, N-B-C and C-B-C bonds at B site can be regulated through solid-state reaction between boron nitride (BN) and porous carbon (C) at variable temperatures. The optimized BCN-1100 achieves an outstanding H2O2 selectivity of 89% and electron transfer number of 2.2 (at 0.55 V vs. RHE), with the production of 10.55 mmol/L during 2.5 h and the catalytic stability duration for 15000 cycles. Further first-principles calculations identified the dependency of localized bonding microenvironment on the OOH* adsorption energies and relevant charge states at the boron site. The localized structure of B site with BNC2-Gr configuration is predicted to be the highest 2eORR activity.
In the present work, a stable two-dimensional (2D) P2Si monolayer was predicted. The monolayer is semimetallic/metallic under the PBE/HSE06 functional and is mechanically isotropic. The stability of the P2Si monolayer has been proved via cohesive energy, mechanical criteria, molecular dynamics simulation, and phonon dispersion respectively, and the monolayer possesses high carrier mobility which is three times that of MoS2. On the other hand, the catalytic performance of the P2Si monolayer modified with a single transition metals (M = Sc-Cu) atom for the electrochemical reduction of CO2 was investigated, and the monolayer can catalyze CO2 with three constraints: stable molecular dynamics, high migration potential of metal atoms, and suitable band gap for electrocatalyst after metal doping exhibiting excellent catalytic stabilization activity and CRR selectivity. In addition, the reduction product of V@P2Si is HCOOH with an overpotential as low as 0.75 V, and the most suitable reaction path is *CO2 → *CHOO → O*CHOH → * + HCOOH with the final reduction product HCOOH obtained. As a whole, the above results endow the P2Si monolayer to be a good 2D material holding great promises for applications in nanoelectronics and CO2 reduction catalysts.
Pyrochlore-structured polyantimonic acid (PAA) is a potential high-capacity electrode material, but its innately poor electroconductivity (~10−10 S/cm) seriously impairs its electrochemical reversibility for lithium-ion storage. Herein, we report design and synthesis of a novel V-substituted PAA (PAA-V), where V5+ are introduced to partially replace Sb5+. Owing to identical valence and close ionic radius relative to Sb5+, the V5+ cation can constitute the covalent VO6 octahedra framework without changing the pyrochlore crystal structure of PAA. As a result, the V5+-substitution is capable to modulate the electronic structure of PAA with significantly improved electrical conductivity (~10−6 S/cm for PAA-V) and meanwhile decreases the size of crystals with reduced diffusion length for Li+-ions. With varying the ratio of V5+-substitution, the PAA-V with optimized substitution molar ratio (18%) exhibits the best lithium-ion storage performance, delivering a long cycling life with high reversible capacity (731 mAh/g after 1200 cycles at 1 A/g) and outstanding rate capability (279 mAh/g at 15 A/g). More importantly, by pairing the PAA-V as anode and commercial LiFePO4 as cathode, the full cell with a limited negative/positive capacity ratio of 1.2 exhibits decent cycling stability at 1 C after 150 cycles with 85.5% capacity retention.
More and more antibiotics that are difficult to biodegrade have been detected in water environments threatening ecosystems and human health. Therefore, it is urgent to develop efficient water treatment methods to degrade antibiotics. In this work, Co-Fe Prussian blue analogues (PBAs) with different molar ratios were synthesized for peroxymonosulfate (PMS) activation to degrade sulfacetamide (SAM, 10 mg/L). By increasing Co molar ratio, the PMS activation capability and electrochemical properties of PBAs were enhanced. Due to its excellent reactivity (degradation efficiency of 84.2% and mineralization efficiency of 52.79%), cost benefit (electrical energy per order, 0.01019 kWh/L) and lower metal leaching ([Co] = 0.259 mg/L, [Fe] = 0.128 mg/L), PBA-1, the as-prepared catalyst with a molar ratio of cobalt to iron of 1:1, was selected for further study. The radical scavenging experiments and an electron paramagnetic resonance (EPR) trapping experiments were performed and revealed that PBA-1 addition was required to produced •OH and SO4•− from PMS activation. Accordingly, we proposed a PMS activation mechanism and SAM decomposition pathways for PBA-1/PMS reaction system. Besides, a PBA-1@polyvinylidene fluoride (PVDF) catalytic membrane was further prepared to expand the application potential of PBA nanoparticles. The PBA-1@PVDF catalytic membrane was highly effective and exhibited a great reusability; thus, it could be considered for applications in actual water treatment processes.
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62199257
qkjq@cast.org.cn
Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House
