New Journal of Chemistry最新文献

Vertically aligned WO₃ nanoplate films were synthesized on stainless steel (SS) via a simple hydrothermal method. The prepared WO₃ films were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Results of these analyses reveal that the SS surface was well-covered with compact and vertical WO₃ nanoplates with a monoclinic single-crystalline structure. The film obtained through a 2.5 h hydrothermal reaction exhibited excellent photoelectrochemical performance under visible-light illumination and generated an anodic photocurrent of 0.754 mA cm⁻² at 0.8 V (vs. Ag/AgCl). WO₃ photoelectrodes could degrade 98.9% of methylene blue (MB) within 120 min through a photoelectrocatalytic (PEC) process. The stability of the as-prepared photoelectrode was also studied, and no significant reduction in PEC activity was observed after recycling for 5 times. The supreme PEC activity of the aligned WO₃ nanoplate films can be attributed to the direct charge transport pathway in the 2D structure and the bias potential applied to reduce the recombination of photogenerated electron–hole pairs.

Considering the increasing demand for gold and the scarcity of mineral resources, this study presents a promising avenue for its recovery from secondary resources. In this paper, N1,N1′-(1,4-phenylene)bis(N1-(4-aminophenyl)benzene-1,4-diamine) and 2,3,5,6-tetrafluoro-p-dibenzaldehyde were successfully prepared by the solvothermal method to synthesize a highly fluorinated covalent organic polymer with imine bonds (N-TFACOP), which can be used to recover gold ions from secondary sources. Covalent organic polymer (COP) materials have controllable structures that can be significantly improved by introducing appropriate functional groups into the structural units. The introduction of fluorine atoms with strong electron-absorbing ability into COP materials not only significantly increases the specific surface area of the materials and provides more surface active sites but also improves the chemical and thermal stability of the materials, even in strong acids and bases. The adsorption capacity for gold was further improved. At pH = 4, adsorption time of 720 min, and adsorption temperature of 45 °C, the maximum adsorption capacity of N-TFACOP for gold was as high as 2975.08 mg g⁻¹. There was no significant decrease in the adsorption rate after six cycles, which proved that the adsorption performance for gold was significantly improved by N-TFACOP. Au(III) was reduced to monomeric gold by complexation and redox reaction between the functional atom (N) and Au(III). In summary, we verified the adsorption potential of a novel covalent organic polymer for Au(III), which provides a strong reference for the recycling of the precious gold metal from secondary resources and the protection of environmental resources.

Transition metal sulfides are promising non-noble metal catalysts for hydrogen production through electrochemical water splitting due to their rich redox behaviors, good conductivity and stability. Herein, mesoporous Cu₂MoS₄ nanocubes were rapidly synthesized at room temperature via a novel electron beam irradiation-assisted method. During the electron beam irradiation process, a large number of free radicals were produced. These radicals are highly active and effectively accelerate the rapid formation of Cu₂MoS₄ nanocubes with I-phase. The as-obtained Cu₂MoS₄ nanocubes presented a mesoporous structure, which not only provides abundant electrocatalytic active sites but also facilitates the diffusion of electrolyte and the overflow of H₂ bubbles. As a result, the titled catalyst exhibits good electrocatalytic activity toward the hydrogen evolution reaction (HER) in acidic, neutral and alkaline electrolytes. Specifically, the catalyst with an irradiation dose of 300 kGy exhibited the best HER performance with low overpotentials of 160.2 mV, 256.2 mV and 225 mV to achieve a current density of 10 mA cm⁻² in 0.5 M H₂SO₄, 1 M PBS and 1 M KOH, respectively. This work demonstrates the effectiveness of electron beam-assisted synthesis in producing well-defined nanostructured catalysts for water splitting.

A new series of β-functionalized meso-tetraphenylporphyrins bearing 4-methoxyphenyl, 3,5-dimethoxyphenyl and 3,4,5-trimethoxyphenyl groups appended selectively to the single pyrrole unit of the porphyrin macrocycle, H₂TPPR₂ (where R = p-CH₃O-Ph, m-CH₃O-Ph and m,p-CH₃O-Ph), and their Co(II), Ni(II), Cu(II) and Zn(II) metal complexes were synthesized, characterized and meticulously examined for their adjustable electronic spectral, electrochemical and structural attributes. A gradual bathochromic shift of absorption bands (Δλ_max = 5–8 nm) was observed in these porphyrins relative to the unsubstituted parent porphyrin, H₂TPP. A progressive cathodic shift in the first ring oxidation potential was observed in the series. Among all free base porphyrins, H₂TPP(p-CH₃O-Ph)₂ showed the maximum red shifted absorption and the largest cathodic shift in the first ring oxidation, unveiling the effective electron donation via the +R effect of methoxy groups placed at the para position of β-phenyl rings. Within this framework, fine-tuning of the HOMO–LUMO gap accompanied by a gradual reduction in energy was observed which followed the trend H₂TPP(m,p-CH₃O-Ph)₂ (2.22 V) > H₂TPP(m-CH₃O-Ph)₂ (2.13 V) > H₂TPP(p-CH₃O-Ph)₂ (2.08 V). Single crystal X-ray analyses of H₂TPP(p-CH₃O-Ph)₂, ZnTPP(m-CH₃O-Ph)₂ and CuTPP(m-CH₃O-Ph)₂ unfolded planar, quasi-planar and saddle conformations respectively. Hirshfeld surface and 2D fingerprint plot analysis were also performed to see the significant intermolecular interactions. Further, DFT and TDDFT calculations were performed to gain a deeper understanding of the observed experimental results.

Atrazine, a human-made herbicide, is infamous for its endocrine-disrupting properties, with adverse consequences on the immune, reproductive, and nervous systems. Consequently, effective recognition of atrazine in various environments, such as water, is critically important. This work presents a precise and efficient method for detecting atrazine across various environments, utilizing a well-established electrochemical technique. A metal organic framework (MOF) ZIF-67 has been synthesized and employed as a catalyst for the electrochemical detection of the triazine herbicide atrazine. Structural, morphological, and chemical analyses were conducted to evaluate the sensing material and to elucidate the interactions between the sensor and the analyte. The ZIF-67 was then integrated on the surface of the working electrode (carbon paste electrode (CPE)) to form a ZIF-67 modified-CPE (ZIF-67/MCPE). The ZIF-67/MCPE was utilized to detect atrazine by electrochemical techniques including differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The sensor demonstrated excellent sensitivity and was effective in detecting atrazine. The modified sensor demonstrated a lower limit of detection (LLOD) of 3.7 μM within a linear concentration range of 4–44 μM and exhibited a strong linear correlation efficiency of 0.97. Computational results corroborated the experimental findings, revealing that the combination of ZIF-67 with atrazine forms minor triangular structures and exhibits enhanced dynamics compared to the pristine MOF. This improvement in the crystallinity of the ZIF-67 MOF with atrazine is attributed to the negative binding energy and reduced energy gap at the interface between the MOF and atrazine. Additionally, the sensor's practical application was evaluated by testing it on sewage water and fresh liquid milk. The sensor demonstrated an exceptional ability to detect atrazine, with a recovery rate ranging from 96% to 99%. This approach holds promise for developing electrochemical or solid-state devices for real-time atrazine monitoring.

This study investigates the modification of graphene oxide (GO) with ethylenediamine (EDA) to enhance its interlayer spacing to 1.04 nm and increase water flux to 879.2 L m⁻² h⁻¹. Subsequently, gallic acid (GA) was employed for secondary modification of the ethylenediamine-modified graphene oxide (EGO). Cellulose acetate (CA) served as the substrate for membrane fabrication, with the GA–EGO membrane prepared via a vacuum filtration method. The fundamental properties of the GA–EGO membrane were characterized using various analytical techniques, including water contact angle measurements and Fourier transform infrared spectroscopy (FTIR). The results indicated that the optimal concentration of GA in the GA–EGO membrane was 1 mg. Under these conditions, significant alterations to the membrane surface were observed, achieving a water contact angle of 0°, which corresponds to a superhydrophilic state. The GA–EGO membrane demonstrated an increased water flux of 1058.2 L m⁻² h⁻¹ and exhibited excellent emulsion separation capabilities, achieving a separation efficiency of 95.3% for coal–oil emulsions. Notably, after ten cycles of use, the GA–EGO membrane retained its operational efficiency. Furthermore, it maintained a separation efficiency exceeding 90% for emulsions derived from various oils, underscoring its promising potential for practical applications.

The oxidation of glycerol to dihydroxyacetone (DHA) represents an efficient and economical process route. Although preparing Au/CuO catalysts from plant constituents has emerged as a novel approach for synthesizing biocompatible products, the complexity of plant constituents means that the active components still need to be clarified, making it challenging to control catalytic activity. In this study, we effectively separated and identified the active components of Syringa oblata Lindl. (SoL) leaf using column chromatography, and synthesized a series of Au/CuO catalysts from the different separated samples. Glycerol catalytic evaluation experiments showed that the S3 fraction, mainly consisting of phenolic substances, exhibited the highest catalytic activity, with a glycerol conversion rate of 86.6% and DHA selectivity of 82.0%, exceeding the activity of most current catalysts. A series of experiments and characterizations demonstrated the differences in reducibility and protective ability among the separated samples, and the preparation and glycerol reaction conditions for optimal performance are systematically optimized. This work provides in-depth insights into the preparation of catalysts using plant-based methods.

Both the use of renewable natural sources to prepare catalytic materials and the Meerwein–Ponndorf–Verley (MPV) reduction of carbonyl compounds are very attractive topics in catalysis. Neohesperidin (NES) with rich oxygen-containing groups can bind to various metal ions. In this work, NES has been used as the ligand to coordinate Zr(IV) for the synthesis of a porous coordination polymer (Zr-NES). Various characterization studies demonstrated the formation of robust porous inorganic–organic frameworks and strong Lewis acid–base sites in Zr-NES. Due to the presence of coordinatively unsaturated Zr sites, Zr-NES had highly active Lewis acid sites, so it can efficiently catalyze the hydrogenation of 5-hydroxymethylfurfural (HMF) to prepare 2,5-bis-(hydroxymethyl)furan (BHMF). After 2 h at a mild temperature of 120 °C, a BHMF yield of 99.0% with turnover frequency (TOF) of 8.5 h⁻¹ could be obtained. This robust bifunctional acid–base Zr-NES was also demonstrated to be effective in one-step reductive etherification of 5-HMF to 5-[(1-methylethoxy)methyl]-2-furanmethanol (MEFA), a potential biomass-derived fuel additive, with 90% yield. Kinetic studies revealed that the activation energy for CTH of 5-HMF was 44.73 kJ mol⁻¹, accounting for the high reaction rate. Due to the strong interactions between Zr⁴⁺ and oxygen-containing groups, Zr-NES was highly stable and could be reused without a significant decline in activity.

Here we report the synthesis of series of bipyridine-based porous polymers as macroligands for molecular copper complexes. The resulting Cu@N-POP solids efficiently catalyze the dehydrogenative N–N coupling of di-p-tolylamine into the corresponding hydrazine using oxygen as the oxidant. The heterogenization of the Cu-based catalyst within porous macroligands improved the catalytic activity with regard to previously reported Cu-based molecular homogeneous systems. Increasing the availability of the bipyridine sites to Cu coordination led to enhanced catalytic performances.

Herein, a heterostructured design strategy involving Ag nanoparticles (Ag NPs) stabilized with 5-(2-mercaptoethyl)tetrazole and immobilized on titania nanotubes for the oxygen reduction reaction (ORR) is reported. Bare titania nanotubular layers were annealed in air (TNT) or in a hydrogen atmosphere (hTNT), and their composites with tetrazole-stabilized Ag NPs (tz-Ag NPs) were evaluated for their ORR performance in alkaline media. The activity of the tz-Ag NP/TNT composites was shown to correlate with TNT doping level, which can be controlled by varying the annealing conditions. In all cases, the tz-Ag NP/hTNT composite shows more positive ORR onset and half-wave potentials (E_1/2) than the tz-Ag NP/TNT composite. An increase in tz-Ag NP loading onto the TNT and hTNT matrix leads to a decrease in the overpotential of O₂ reduction. The hTNT electrocatalyst loaded with a high amount of tz-Ag NPs (24 μg cm⁻²) exhibits superior ORR activity over a bare Ag electrode in terms of ORR onset and half-wave potentials. Ag NPs stabilized with tetrazole demonstrate an improved ORR performance in alkaline media compared to Ag NPs capped with citrate. The TNT electrodes loaded with tz-Ag NPs have shown high electrocatalytic activity toward the ORR indicating their suitability as cathode materials in alkaline fuel cells.