Journal of Colloid and Interface Science最新文献

The development of advanced bifunctional oxygen electrocatalysts for the oxygen reduction reactions (ORR) and oxygen evolution reactions (OER) is crucial for the practical application of zinc-air batteries (ZABs). Herein, porous carbon nanosheets integrated with abundant graphene-wrapped CoO and CoNx (CoO/CoNx-C) were successfully fabricated through a simple one-step pyrolysis. With convenient porous channel and large accessible surface, abundant CoO/CoNx species and graphene wrapping structure, CoO/CoNx-C exhibited a half-wave potential of 0.844 V in ORR and an overpotential of 384 mV (@10 mA cm^-2) in OER in the alkaline environment and presented a negative shift of 9 mV in ORR after 8000 cycles and positive shift of 19 mV in OER after 2000 cycles. Electrochemical acid-washing and comparison analysis revealed that the ORR activity mainly originated from CoO nanoparticles, while CoNx species were greatly responsible for OER catalysis. Furthermore, the as-prepared CoO/CoNx-C endowed the rechargeable liquid and solid ZABs with superior power density (161 mW cm^-2 for liquid ZABs and 137 mW cm^-2 for solid ZABs) and long-term stability (stable in 1000 h charge/discharge tests) compared to commercial catalysts. This work provides a feasible strategy for cobalt/carbon hybrid materials as advanced bifunctional electrocatalysts for ZABs.

Photocatalytic reduction of CO₂ to valuable chemicals is an effective strategy to address the environmental problems and energy crisis. Covalent organic frameworks (COFs) are emerging materials known for their excellent diverse properties, albeit limited by special synthetic methods, including high temperature (120 °C) and the necessity of inert gas atmosphere. Herein, a novel synthesis method under room temperature and air was optimized to form TpPa-COF (TP-COF) by p-phenylenediamine (Pa) and 2,4,6-triformyl phloroglucinol (Tp) through electrostatic self-assembly. To further expand the application scope of TP-COF, a heterojunction structure was constructed by in-situ growth of TP-COF onto TiO₂ to form TiO₂@TP-COF. In the photocatalytic CO₂ reaction of TiO₂@TP-COF composites, TiO₂ acts as a reduction site to reduce CO₂ to CO, and triethanolamine (TEOA) acts as a hole-sacrificing reagent. It was demonstrated by in situ X-ray photoelectron spectroscopy (XPS) that the direction of electron transfer in the TiO₂@TP-COF composites flowed from TP-COF to TiO₂. Meanwhile, TEOA on TP-COF was oxidized to consume holes and produce protons for the reduction of CO₂. Combining the advantages of organic and inorganic semiconductors, the heterojunction structure effectively improves the photocatalytic properties of TiO₂@TP-COF under visible light irradiation. TiO₂@TP-COF demonstrates a remarkable photocatalytic CO₂ reduction rate of 133.37 μmol/g/h at λ = 420 nm, which is 3.19 and 2.88 times higher than that of TP-COF and TiO₂, respectively, while exhibiting a selectivity of 73 % for CO. This convenient method of synthesizing TiO₂@TP-COF catalysts will open up new perspectives for future COF-based materials.

Emerging contaminants (ECs) pose great challenges to water treatment technology due to their complexity and high harm. In this paper, the method of dielectric barrier discharge (DBD) plasma coupled with iron-based catalyst (FeNC) activating periodate (PI) was first designed for ECs removal. The ingenious introduction of FeNC not only promotes the Fenton-like reaction of DBD system but also reduces the PI activation energy barrier and accelerates the electron shuttle between PI and pollutants. Based on the parameters evaluation of machine learning (ML), the calcination temperature of 575 ℃ and 17 % N addition were determined for best catalytic performance. XRD, Raman spectroscopy, XPS and density functional theory (DFT) analysis show that optimized catalyst has better electron shuttle characteristics and PI activation ability. Compared to DBD (78 %) and DBD/PI (94 %), DBD/FeNC/PI could achieve 100 % degradation efficiency of sulfadiazine (SDZ) in 12 min with high reaction rate. In addition to the effects of ROSs (¹O₂, OH and O₂^-), the efficient electron transfer mediated by FeNC and PI is the key to promoting the degradation of pollutants. The progressive dissociation of pyrimidine ring under the action of OH and electron transfer is the main pathway of SDZ degradation. The toxicity of intermediate products produced by the system is generally lower than that of SDZ. The system still has a high SDZ removal efficiency in actual water and has a good removal effect for other types of ECs, which also makes the system have a better practical prospect.

Graphitic carbon nitride (g-C₃N₄) has been regarded as highly potential photocatalyst for solar energy utilization. However, the restricted absorption of visible light for pristine g-C₃N₄ significantly limits the solar-light-driven chemical reaction efficiency. Herein, structurally distorted g-C₃N₄ nanosheets with awakened n-π* electron transition were successfully synthesized through hexamethylenetetramine (HMTA)-involved supercritical CO₂ (scCO₂) treatment and following pyrolysis of melamine precursor. ScCO₂ treatment was conductive to homogeneously dissoving melamine precursor and HMTA, and then the modification by HMTA with three-dimensional structure changed the g-C₃N₄ photocatalyst from a symmetrical planar structure to an asymmetrical non-planar structure. The resulting awakened n-π* electron transition in structurally distorted g-C₃N₄ nanosheets greatly extended the photoresponse range of g-C₃N₄ and increased the amount of catalytically active π electrons. Moreover, the unique distorted structure of g-C₃N₄ enhanced photogenerated charge carriers separation and provided sufficient reactive sites for photocatalytic H₂ production. Consequently, the structurally distorted g-C₃N₄ nanosheets exhibited enhanced photocatalytic H₂ production performance, which was up to 6.4 times that of pristine g-C₃N₄. This work presents a promising scCO₂ strategy towards precursor treatment to regulate the microstructure of g-C₃N₄, and provides valuable guidance to obtain efficient g-C₃N₄ photocatalyst by microstructure engineering.

Developing insertion-type anodes is essential for designing high-performance "rocking chair" zinc-ion batteries. BiOCl shows great potential as an insertion-type anode material for Zn²⁺ storage due to its high specific capacity and unique layered structure. However, the development of BiOCl has been significantly hampered by its poor stability and kinetics during cycling. In this study, Br-doped and carbon-coated BiOCl ultrathin nanosheets (Br-BiOCl@NC) are synthesized as high-performance anodes. The ultrathin nanosheet morphology facilitates Zn²⁺/H⁺ transfer and the Br doping reduces the Zn²⁺/H⁺ diffusion barrier. Additionally, the carbon coating enhances the electronic transfer. Furthermore, an insertion-conversion mechanism involving H⁺ and Zn²⁺ storage is revealed by ex-situ tests. Therefore, Br-BiOCl@NC exhibits a high discharge capacity of 174 mA h/g at 500 mA/g without capacity degradation after 1000 cycles. The Br-BiOCl@NC//MnO₂ full cell presents a discharge capacity of ≈ 120 mA h/g at 200 mA/g. This work offers valuable insights for the design of high-performance insertion-type anode materials in zinc-ion batteries.

Porous carbons with large surface area (>3000 m²/g) and heteroatom dopants have shown great promise as electrode materials for zinc ion hybrid capacitors. Centralized mesopores are effective to accelerate kinetics, and edge nitrogen can efficiently enhance pseudocapacitive capability. It is a great challenge to engineer centralized mesopores and edge nitrogen in large-surface-area porous carbons. Herein, a strategy of melamine-boosted K₂CO₃ activation is proposed to prepare edge-nitrogen-doped hierarchical porous carbons (ENHPCs). KOCN generated by K₂CO₃ reacting cyano groups (-CN) couples with K₂CO₃ activation engineers large-surface-area porous carbon. KCN in-situ generated by KOCN etching carbon atoms plays a template role in constructing centralized mesopores. Edge-nitrogen skeleton is formed by g-C₃N₄ losing -CN, and then in-situ integrated into porous carbon skeleton. The efficiency of melamine-boosted K₂CO₃ activation reaches the highest at a melamine/lignin mass ratio of 0.5, where the optimized ENHPCs (ENHPC-0.5) have a large surface area of 3122 m²/g, a mesopore architecture (2.8 nm) with a mesoporosity of 60.5 % and a moderate edge-N content of 1.9 at.%. ENHPC-0.5 cathode displays a high capacitance of 350F/g at 0.1 A/g, an excellent rate capability of 129F/g at 20 A/g and a robust cycling life. This work provides a novel strategy to prepare heteroatom-doped high-surface-area porous carbons for zinc ion hybrid capacitors.

Modern microelectronics industries urgently require dielectric materials with low thermal expansion coefficients, low dielectric constants, and minimal dielectric loss. However, the design principles of materials with low dielectric constants and low thermal expansion are contradictory. In this study, a new diamine monomer containing a dibenzocyclooctadiene unit (DBCOD-NH₂) was designed and synthesized, which was subsequently polymerized with high fluorine content 4,4'-hexafluoroisopr-opylidene diphthalic anhydride and 4,4'-diamino-2,2'-bis(trifleoromethyl)biphenyl to obtain a series of fluorinated polyimides (PIs). Due to the unique conformational transition of the eight-membered carbon ring, the resulting PI can reach a low averaging thermal expansion coefficient (CTE) of only 12.27 ppm/K over 5-150 ℃ with a size change rate of only 0.16 %. Surprisingly, the synergistic effect of DBCOD-NH₂ with the other two monomers enhances the dielectric performance of the PIs. At an electric field frequency of 10 MHz, the dielectric constant (D_k) and the dielectric loss (D_f) can be reduced to as low as 2.61 and 0.00194, respectively. The strategy used herein largely tackles the challenge of balancing low D_k with low CTE. Furthermore, these PI films also exhibit good thermal stability (with 5 wt% weight loss temperatures ranging from 453 to 537 ℃ in N₂, and glass transition temperatures of 305-337 ℃) and robust mechanical properties (with a tensile modulus of 1.88-2.29 GPa and an elongation at break of 6.36-8.11 %). The combination of low thermal expansion and excellent dielectric properties renders these PIs highly promising for applications in the microelectronics and telecommunications industries.

The simultaneous generation of hydrogen (H₂) and the oxidative transformation of organic molecules through photocatalytic processes represents a highly promising dual-purpose strategy. This approach obviates the necessity for sacrificial agents while augmenting catalytic efficiency, thereby facilitating the integrated production of high-value chemicals and renewable energy carriers. Polymeric carbon nitride (PCN) has emerged as a leading candidate among coupled photocatalysts. Nevertheless, PCN's efficacy is constrained by the inefficient separation of charges and the functional limitations of its active sites. Herein, the incorporation of P-N₃ groups into PCN introduces active sites with pronounced charge asymmetry, resulting in strong local charge polarization. This asymmetric charge distribution, mediated by the P-N₃ groups, significantly enhances exciton dissociation. Remarkably, the P-N₃-modified narrow-dimensional fragmented carbon nitride (P-CNNS) achieves an 85 % conversion rate for 4-MBA with nearly 100 % selectivity, and a hydrogen evolution rate of 27.9 mmol g^-1 (with Pt as a co-catalyst), representing 6.2 times higher than that of bulk carbon nitride (BCN). The charge-polarized sites facilitate the transfer of electrons, which is a pivotal process in the activation of 4-methoxybenzyl alcohol (4-MBA). Additionally, these sites serve as adsorption sites, facilitating the oxidation of 4-MBA into anisaldehyde (AA). This work underscores the potential of non-metallic site catalysts for a wide range of coupled photocatalytic applications.

Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) has been widely used as the hole transport layers (HTLs) for perovskite solar cells (PSCs), especially in all-perovskite tandems. However, the energy-level mismatch between PEDOT:PSS and perovskite leads to large voltage deficit in PSCs, and the dopant PSS with high acidity and hygroscopicity conspicuously deteriorates the device stability. Herein, a powerful strategy for constructing self-assembled polymer HTLs is developed by in-situ polymerization of functionalized 3,4-ethylenedioxythiophene with carboxylic acids as side groups. This strategy facilitates the formation of a self-assembled polymer monolayer to be strongly anchored on the glass substrate, and enables the elimination of the dependence of PSS doping for traditional PEDOT. The obtained polymer HTL PEDOT-l-COOH (PTLC) exhibits an appropriate energy-level alignment with the perovskite, which enhances the charge carrier collection at the interfaces. Besides, the self-assembled PTLC with high structural ordering favors the heterogeneous nucleation of perovskite, resulting in the formation of high-quality perovskite films with superior buried interfaces. Consequently, the inverted PSCs based on PTLC demonstrate a champion conversion efficiency of 20.30 % with a high open-circuit voltage of 1.03 V which are much higher than that of PEDOT:PSS-based devices (14.47 %, 0.79 V). More encouragingly, the unsealed devices with PTLC deliver outstanding operational stability by maintaining 90 % of initial efficiency for 950 h under ambient condition with a relative humidity of 30 % ± 5 %. This work opens a new avenue for developing self-assembled PEDOT-based HTLs for optoelectronic devices, and paves the way for further improving the performance of inverted PSCs.

Rational regulation of interface structure in photocatalysts is a promising strategy to improve the photocatalytic performance of carbon dioxide (CO₂) reduction. However, it remains a challenge to modulate the interface structure of multi-component heterojunctions. Herein, a strategy integrating heterojunction with facet engineering is developed to modulate the interface structure of metal-organic frameworks (MOF)-based heterojunctions. A series of core-shell UiO-66 (Zr-MOF)-loaded MIL-125 (Ti-MOF) heterojunctions with exposed specific facets were prepared to enhance the separation efficiency of photogenerated electrons-holes in CO₂ photoreduction. Impressively, MIL-125_to@UiO-66 with exposed {1 1 1} facet exhibits an excellent CO production rate (56.4 μmol g^-1 h^-1) and selectivity (99 %) under visible light irradiation without any photosensitizers/sacrificial agents, being 1.4 and 11.3 times higher than individual MIL-125_to and UiO-66, respectively. The type-II heterojunction significantly enhances the separation of photogenerated electrons-holes in physical space. The photogenerated electrons migrate from Zr in UiO-66 to Ti in MIL-125_to, promoting a spatial synergy between CO₂ reduction on MIL-125_to and H₂O oxidation on UiO-66. Compared with MIL-125_rd@UiO-66 with exposed {1 1 0} facet and MIL-125_ds@UiO-66 with exposed {0 0 1} facet, MIL-125_to@UiO-66 with exposed {1 1 1} facet improves the exposure of surface-active Ti sites, thereby enhancing the adsorption/activation of CO₂ to generate the *COOH intermediate. This work provides an effective strategy for designing MOF-based heterojunction photocatalysts to improve photocatalytic performance.