Latest ArticlesIn this study, through direct pyrolysis of a nitrogen-rich metal-organic framework of Fe-BTT at different temperatures and followed by acid treatment, we prepared a series of Fe–N–CT (T = 800–1000 ℃) composite catalysts with uniform cubic morphology and homogeneously distributed active sites. Acid leaching leads to the removal of excess Fe NPs and the exposure of more pyridinic N and porphyrin-like Fe–Nx sites and creates a higher specific surface area. Structural and electrochemical performance test results showed that Fe–N–C900 catalyst exhibited the highest selectivity for CO product at –1.2 V vs. Ag/AgCl, with 496 mV of overpotential and 86.8% of Faraday efficiency, as well as excellent long-term stability, due to the good inheritance from rich-N Fe–BTT precursor.
Heterogeneous catalysis is a vivid branch of traditional catalysis field, with the advantage of high efficiency and being easily separated from reactants and products after reaction, and have received widespread attentions in large-scale industrial production, especially in the field of energy utilization. Boron has been found to be a key functional component for designing high-performance heterogeneous catalysts. In this review, we cover and categorize the past and recent progress in boron-containing materials and their applications in heterogeneous catalysis particularly in energy‐related fields. The fundamental roles of boron components in the emerging heterogeneous catalysis of construction, regulation and stabilization of active phases/sites are highlighted, with the emphasis on how they regulating structural and electronic properties of host materials. We then categorize boron-containing catalysts into six kinds mainly including intermetallic boride catalysts, metal boride-derived catalysts, boron-doped catalysts, metal boride-decorated catalysts, boron-containing compounds as catalyst supports, and single-boron-site catalysts, as well as try to establish structure-catalytic activity relationship. The catalytic applications of these six boron-containing catalysts are discussed separately, focusing on the energy-related reactions such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR) and nitrogen reduction reaction (NRR). Finally, the opportunities and challenges related to boron-containing compounds in the field of catalysis are prospected.
NH3 plays an essential role in human life since it is an important raw material for fertilizers, plastics and rubbers production. As an NH3 synthesis technology under ambient conditions, electrocatalytic N2 reduction reaction (NRR) has great potential to replace the energy-intensive Haber-Bosch process. The key of electrocatalytic NRR is the exploration of efficient catalysts. Transition metal Mo is promising since it exists naturally in nitrogenase due to the unique Mo-N2 interaction; particularly in the form of 2D material such as MoSe2, the surface area is maximized for more active sites. However, the NRR performance of MoSe2 is still unsatisfactory because Mo is only exposed at the semi-open edge, and the electronegative Se-mantled surface area remains inaccessible to N2. Herein, we propose a simple and effective strategy to create high-concentration Se vacancies in MoSe2 through heteroatom doping induced lattice strain, which effectively enhances the Mo-N2 interaction on the surface area. In result, high NH3 yield (3.04 × 10–10 mol s–1 cm–2) and Faraday efficiency (21.61%) are attained at –0.45 V vs. RHE in 0.1 mol/L Na2SO4.
A novel atmospheric pressure matrix-assisted laser desorption ionization mass spectrometry (AP-MALDI-MS) method was established for the facile detection of pesticides in ambient environment. Four kinds of multi-walled carbon nanotubes (MWCNTs)-based matrix were synthesized and utilized to enhance the ionization efficiency of pesticides. Organophosphorus, anilinopyrimidine, carbamate, triazine, triazole and benzimidazole pesticides were directly desorbed and ionized from MWCNTs-based matrix in ambient environment, showing clear background and good sensitivity. In a comparison, Fe3O4-doped MWCNTs improved the intensity of pesticide ions more than the other three matrices. Moreover, MWCNTs-based matrix exhibited better performance than organic matrix. Quantitative analysis of pesticides using AP-MALDI-MS was validated to be adequate linearity, repeatability and sensitivity. Overall, AP-MALDI-MS combined with MWCNTs-based matrix enables the directly qualitative and quantitative analysis of pesticides in ambient environment.
Photocatalytic selective transform native lignin into valuable chemicals is an attractive but challenging task. Herein, we report a mesoporous sulfur-doped carbon nitride (MSCN-0.5) which is prepared by a facile one-step thermal condensation strategy. It is highly active and selective for the cleavage Cα−Cβ bond in β−O−4 lignin model compound under visible light radiation at room temperature, achieving 99% substrate conversion and 98% Cα−Cβ bond cleavage selectivity. Mechanistic studies revealed that the Cβ−H bond of lignin model compounds activated by holes and generate key Cβ radical intermediates, further induced the Cα−Cβ bond cleavage by superoxide anion radicals (•O2−) to produce aromatic oxygenates. Waste Camellia oleifera shell (WCOS) was taken as a representative to further understand the reaction mechanisms on native lignin. 33.2 mg of monophenolic compounds (Vanillin accounted for 22% and Syringaldehyde for 34%) can be obtained by each gram of WCOS lignin, which is 2.5 times as that of the pristine carbon nitride. The present work offers useful guidance for designing metal-free heterogeneous photocatalysts for Cα−Cβ bond cleavage to harvest monophenolic compounds.
Boron/nitrogen-co-doped carbon (BCN) nanosheets decorated with Fe2O3 nanocrystals (Fe2O3–BCN) were cast on a glassy carbon electrode (GCE) and applied as an electrochemical sensor to effectively detect paraquat (PQ), a toxic herbicide, in aqueous environments. A linear experiment performed using square wave voltammetry (SWV) under optimized experimental conditions produced a decent linear relationship and a low detection limit (LOD) of 2.74 nmol/L (S/N = 3). Repeatability, reproducibility, stability, and interference experiments confirmed that the Fe2O3–BCN/GCE system exhibited decent electrochemical sensing performance for PQ molecules. Notably, the designed sensor showed high selectivity and a decent linear relationship with PQ concentration in natural water samples. To the best of our knowledge, this is the first study on the preparation of Fe2O3–BCN nanosheets for PQ detection. The proposed sensor can be employed as an effective alternative tool for distinguishing and processing PQ.
Oxygen vacancy induced photothermal effect is of great significant but lack of adequate attentions for environmental remediation. In this paper, green recyclable ZnO/ZnFe2O4 with oxygen vacancy was prepared by a solvothermal-calcination method. The UV-vis light capture ability of ZnO/ZnFe2O4 microspheres is improved with the multiple light reflections due to the yolk-shell structure, and the oxygen vacancy expands the absorption range of photocatalyst and enhances photothermal conversion. The optimized photocatalyst can heat the solution from room temperature to 70 ℃ within 60 min of visible light illumination, and the light to heat conversion efficiency is achieved by 61.3%. Compared with the degradation efficiency at 20 ℃, photothermal catalysis achieves a stable degradation in 80 min, and the degradation efficiency is increased by 41.5%. This can be attributed to the fact that light induced thermal energy accelerates the migration of electrons and holes, and promotes the diffusion of free radicals by heating active centers in situ. The active species contributing to the degradation, in order of importance, are the superoxide radical, hydroxyl radical, hole and electron. The light-to-thermal assisted photocatalysis with ZnO/ZnFe2O4 provides a new sight for the pollution control in the future practical applications.
Graphene oxide (GO) with one-atom-thick exhibit remarkable molecule sieving properties, but its low permeance flux renders it difficult to be applied in practice as a high-permeance separation membrane. In this study, we design complex membrane from covalently crosslinked GO, polydopamine (PDA), and 3-aminopropytriethoxysilane (APTES) as building blocks to fabricate the high-permeance GO-based membrane via the vacuum filtration method. A branched crosslinking product (PDA/APTES) working as a clamp grasped the hydrophilic functional groups (hydroxyl, epoxy, carboxyl) on GO for improving the GO membrane flux. The interlayer structure of the GO membrane was optimized according to the crosslinker concentration, reaction time, initial pH, and temperature for RGO/PDA/APTES (RGPA) in this study. At the optimized reaction conditions including the crosslinker concentration of 1.4 mL/L, the temperature of 80 ℃, the time of 16 h, and the initial pH of 8.5 for RGPA mixture, the interlayer gallery of RGPA membrane was effectively tunes, endowing high flux ranging from 11.98 L m−2 h−1 to 1823.97 L m−2 h−1. Besides, the RGPA membrane ensured the high rejections to dye solutions such as methylene blue (MB) (> 99%) and congo red (CR) (> 90%). Meanwhile, the superior reusable performance of the RGPA membrane was achieved, together with the rejections for MB and CR to 96.32% and 93.1% after 4 cycles, respectively. Also, the RGPA membrane possessed superior anti-fouling performances for bovine serum albumin (BSA) aqueous solution and excellent stabilities in harsh conditions (pH 3, 7 and 11). Grafting the crosslinker onto GO nanosheets exhibits the distinct advantages of achieving the high flux, high rejections to dyes, and superior reusable performance of membranes, posing a great application potential for membrane separation technology in wastewater treatment.
For circulating tumor cells (CTCs)-based cancer diagnosis and monitoring, effective enrichment and specific analysis of CTCs present significant challenges. The biomembrane interfaces can enhance the high-affinity interactions between various receptors and ligands in life activities by mediating the rearrangement and positioning of membrane-bound components through its fluidity. Inspired by this, we have constructed a multivalent membrane nano-interface using aptamer-linked liposomes for the efficient capture of CTCs. Furthermore, the subsequent introduction of rolling circle amplification (RCA) reaction has increased the number of aptamers and extended them to the surrounding space to improve the affinity of the membrane nano-interface for CTCs. After CTCs are enriched, alkaline phosphatase overexpressed on the surface of tumor cells is used as endogenous enzyme-mediated signal amplification by catalyzing 4-nitrophenyl phosphate (pNPP) with color change, achieving the analysis of CTCs. Finally, the enrichment and visual analysis of human hepatocellular carcinoma (HepG2) with a detection limit of 10 cells/mL can be obtained by integrating the multivalent membrane nano-interface and endogenous enzyme signal amplification. The detection of the target in the serum proved this method has the potential for further clinical application and provides a potential method for studying the correlation between alkaline phosphatase dimer and cancer progression.
Heteroatom doped porous carbon materials have emerged as essential cathode material for metal-air battery systems in the context of soaring demands for clean energy conversion and storage. Herein, a three-dimensional nitrogen-doped carbon self-supported electrode (TNCSE) is fabricated through thermal treatment and acid activation of raw wood. The resulting TNCSE retains the hierarchical porous architecture of parent raw lumber and holds substantial defect sites and doped N sites in the carbon skeleton. Assembled as a cathode in the rechargeable zinc-air battery, the TNCSE exhibits a superior peak power density of 134.02 mW/cm2 and an energy density of 835.92 mAh/g, significantly exceeding the ones reference commercial 20% Pt/C does. More strikingly, a limited performance decay of 1.47% after an ultra long-period (500 h) cycle is also achieved on the TNCSE. This work could offer a green and cost-save approach for rationally converting biomass into a robust self-supporting cathode material for a rechargeable zinc-air battery.