Environmental Functional Materials最新文献

Heterogeneous advanced oxidation processes (AOPs) over nanostructured catalysts have been developed as a potential technique for wastewater treatment with the advantages, including high performance, wide operational pH range, and low chemical dosage. However, the surface reaction process and the correlation of catalyst properties and catalytic performance still need to be clarified. In this perspective, we overviewed the heterogeneous catalytic reaction steps of AOPs and summarized the monitoring of catalytic process with molecule-scale insights, and proposed the future challenges and research focuses.

Photocatalytic CO₂ reduction is mainly inspired by natural photosynthesis, which could convert CO₂ into high value-added fuels or chemicals through the role of catalysts. However, the photocatalysis efficiency of the currently developed catalysts is far from meeting the actual needs due to the low efficiency of charge separation and energy transfer, and the poor adsorption and activation of CO₂ by catalyst surface. Single-atom catalysts (SACS) show an excellent activity, selectivity and stability in many important reactions, and exhibit great potential in photocatalytic reduction of CO₂ owing to their high atomic utilization and controllability of active sites. In the current review, recent progresses and challenges on SACs for photocatalytic CO₂ conversion systems are presented. The key fundamental principles and reaction mechanisms focusing on charge separation/transfer and molecular adsorption/activation on single-atom photocatalysts for CO₂ reduction are systemically explored. We outlined how single-atom active sites promote the photogenerated carriers separation/transfer and enhance molecular photoactivation. Besides, we put forward some challenges and prospects for the future development of single-atom photocatalysts in CO₂ reduction.

Herein, Pd supported on UiO-66 as well as its NH₂- and NO₂-functional materials with ultra-low Pd loadings (0.05 ​wt%) were synthesized for toluene oxidation. Pd–U, using UiO-66 as the support, exhibited superb catalytic performance, water resistance, and resistance to SO₂. A series of experiments and characterizations revealed that a high dispersion of small Pd clusters, high Pd⁰/Pd_total proportion, better adsorption for toluene, and the best adsorption and activation capacities of gaseous oxygen species enhanced toluene degradation over Pd–U. Additionally, the catalytic mechanism over the Pd-based catalysts was revealed and discussed. Furthermore, the water-resistance and the SO₂ concentration influence were tested and analyzed. Introducing H₂O suppressed the adsorption and activation of toluene as well as gaseous oxygen species, and decreased catalytic performance over the three catalysts. The mechanism of the different impacts of SO₂ on the three catalysts was investigated and elucidated. This study provides guidance for rationally designing catalysts for removing toluene under in-field operating conditions.

Recently metal-free catalysts become very promising in environmental catalysis own to the nature of being free of metals for avoiding metal leaching-related secondary contamination. Herein, a series of boron and nitrogen co-doped graphene nanotubes were first synthesised by thermal treatment of urea, boric acid, and polyethene glycol (PEG, 2000). The materials fabricated under varied thermal conditions, e.g., different pyrolysis temperature and retention time, were characterised through advanced physiochemical techniques. The as-prepared materials showed outstanding catalytic activity for degradation of 4-hydroxybenzoic acid (HBA) via peroxymonosulfate (PMS) activation, whereas the catalyst pyrolysed at 1100 ​°C for 6 ​h (BNG-1100-6h) was found to be the best candidate for environmental remediation, thanks to its engineered surface, exposed active sites, and well-tuned functional groups. Based on the optimal carbocatalyst, reaction conditions such as catalyst loading, PMS dosage, solution pH, and reaction temperature were thoroughly investigated to make it a cost-effective catalytic system. A thermal regenerative path was adopted to enhance the catalyst stability and reusability. Quenching tests and electron paramagnetic resonance (EPR) spectroscopic analysis further revealed the dominant role of singlet oxygen (¹O₂), a non-radical reactive species, in the degradation of HBA. The current research work will not only provide a facile strategy for development of a carbocatalytic system but also open a new perspective for degradation of emerging contaminants such as HBA via a non-radical route.

Electrochemical decomplexation is a common technique that is widely used in industrial wastewater treatment. Although much research has been conducted to improve the decomplexation efficiency of metal–organic complexes [e.g., Ni-ethylenediaminetetraacetic acid (EDTA)], the effects of the fundamental electrochemical reactor configurations in this technology are often underestimated. This research provides insights into the role of the reactor configuration in electrochemical decomplexation of Ni-EDTA through experiments and simulations. Degradation experiments were conducted at the same current density and flow rate in flow-by (FB) and flow-through (FT) electrochemical reactor configurations. The results show that the FT reactor gives a better removal rate (FB: 35%, FT: 46%) and that its energy consumption is half that of the FB reactor [approximately 207.78 (kW·h)/(kg Ni) less]. Experiments show that the stagnant and back-mixing zones for the FT configuration (D_z ​= ​0.062) are smaller than those for the FB configuration (D_z ​= ​0.205). This promotes mass transport in the reaction environment and decreases problems with the reactor performance. Computational fluid dynamics simulations showed that the velocity and potential distributions were both more even for the FT than for the FB configuration. This increases uniformity of mass transport and the current density distribution, produces less ohmic resistance, and greatly improves energy saving. These experimental and simulation results will enable Ni-EDTA electrochemical decomplexation to be achieved with low energy consumption and high efficiency by using appropriate reactor configurations.

Converting CO₂ to fuel is a promising strategy to mitigate the greenhouse effect and achieve ‘carbon neutrality’. Photothermal catalysis has been widely used for CO₂ reduction because it effectively reduces the apparent activation energy of the reaction and provides milder catalytic conditions as well as higher catalytic efficiency than conventional catalytic methods. In this review, the basic principles of photothermal catalytic CO₂ reduction and the factors used to evaluate photothermal catalytic conversion efficiency are introduced. Then, the common types of Ni-based catalysts and their design strategies are summarized and discussed. Among these catalysts, metal oxides have been extensively studied and developed. Accordingly, they currently achieve product yields up to the mmol/(g·h) level. Strategies such as elemental doping and morphology control are often adopted for the modification of photothermal catalysts as a means to improve catalytic performance. Finally, future trends in the field of photothermal catalytic CO₂ reduction are proposed, including mechanistic studies, practical applications, and coupling with other carbon-neutral technologies.