Optimizing Photodetectors in Two-Dimensional Metal-Metalloporphyrinic Framework Thin Films

S-scheme heterojunction Cu-porphyrin/TiO2 nanosheets with highly efficient photocatalytic reduction of CO2 in ambient air

Directly capturing CO2 in ambient air and converting it into value-added fuels using photocatalysis is a potentially valuable technology. In this study, Cu-porphyrin (tetrakis-carboxyphenyl porphyrin copper, CuTCPP) was innovatively anchored on the surface of TiO2 (titanium dioxide) nanosheets to form an S-scheme heterojunction. Based on this, a photocatalytic reaction system for stably converting CO2 in ambient air into value-added fuels at the gas-solid interface was constructed without addition of sacrificial agents and alkaline liquids. Under the illumination of visible light and sunlight, the evolution rate of CO is 56 μmol·g-1·h-1 and 73 μmol·g-1·h-1, respectively, with a potential CO2 conversion rate of 35.8 % and 50.4 %. The enhanced of photocatalytic performance is attributed to the introduction of CuTCPP, which provides additional active sites, significantly improves capture capacity of CO2 and the utilization of electrons. Additionally, the formation of S-scheme heterojunction expands the redox range and improves the separation efficiency of photo-generated charges.

Interface-Engineered 2D Heterojunction with Photoelectric Dual Gain: Mxene@MOF-Enhanced SPR Spectroscopy for Direct Sensing of Exosomes

MXene is widely used in the construction of optoelectronic interfaces due to its excellent properties. However, the hydrophilicity and metastable surface of MXene lead to its oxidation behavior, resulting in the degradation of its various properties, which seriously limits its practical application. In this work, a 2D metal-organic framework (2D MOF) with matching 2D morphology, excellent stability performance, and outstanding optoelectronic performance is grown in situ on the MXene surface through heterojunction engineering to suppress the direct contact between reactive molecules and the inner layer material without affecting the original advantages of MXene. The photoelectric dual gain MXene@MOF heterojunction is confirmed. As a photoelectric material, its properties are highly suitable for the demand of interface sensitization layer materials of surface plasmon resonance (SPR). Therefore, using SPR as a platform for the application of this interface material, the performance of MXene@MOF and its potential mechanism to enhance SPR are analyzed in depth using experiments combined with simulation calculations (FDTD/DFT). Finally, the MXene@MOF/peptides-SPR sensor is constructed for rapid and sensitive detection of the cancer marker exosomes to explore its potential in practical applications. This work offers a forward-looking strategy for the design of interface materials with excellent photoelectric performance.

Excitation generated preferential binding sites for ethane on porous carbon-copper porphyrin sorbents: ethane/ethylene adsorptive separation improved by light

Energy-efficient separation of C2H6/C2H4 is a great challenge, for which adsorptive separation is very promising. C2H6-selective adsorption has big implications, while the design of C2H6-sorbents with ideal adsorption capability, particularly with the C2H6/C2H4-selectivity exceeded 2.0, is still challenging. Instead of the current strategies such as chemical modification or pore space modulation, we propose a new methodology for the design of C2H6-sorbents. With a Cu-TCPP [TCPP = 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin] framework dispersed onto a microporous carbon and a hierarchical-pore carbon, two composite sorbents are fabricated. The composite sorbents exhibit enhanced C2H6-selective adsorption capabilities with visible light, particularly the composite sorbent based on the hierarchical-pore carbon, whose C2H6 and C2H4 adsorption capacities (0 °C, 1 bar) are targetedly increased by 27% and only 1.8% with visible light, and therefore, an C2H6-selectivity (C2H6/C2H4 = 10/90, v/v) of 4.8 can be realized. With visible light, the adsorption force of the C2H6 molecule can be asymmetrically enhanced by the excitation enriched electron density over the adsorption sites formed via the close interaction between the Cu-TCPP and the carbon layer, whereas that of the C2H4 molecule is symmetrically altered and the forces cancelled each other out. This strategy may open up a new route for energy-efficient adsorptive separation of C2H6/C2H4 with light.

2D Metal Porphyrin-Based MOFs and ZIF-8 Composite-Derived Carbon Materials Containing M-Nx Active Sites as Bifunctional Electrocatalysts for Zinc-Air Batteries

The main impediment to the development of zinc-air batteries is the sluggish kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Transition metal N-doped carbon catalysts offer a promising alternative to noble metal catalysts, with metal-organic framework (MOF)-derived carbon material catalysts being particularly noteworthy. Here, we synthesized MxP-Z-C carbon catalysts by combining two-dimensional (2D) metal porphyrin-based MOFs (MxPMFs, x = Fe, Co, Ni, Mn) and three-dimensional zeolitic imidazole framework-8 (ZIF-8) through electrostatic interaction, followed by carbonization. ZIF-8 was inserted between the layers of MxPMFs to prevent its Π-Π stacking, allowing the active sites to become fully exposed. MxP-Z-C demonstrated an impressive catalytic activity for both the ORR and the OER reactions. Among them, FeP-Z-C showed the best catalytic activity. The half-wave potential for ORR was 0.92 V (vs the reversible hydrogen electrode (RHE)), while the overpotential for the OER was 290 mV. In addition, the zinc-air battery assembled by FeP-Z-C exhibited high power density (133.14 mW cm-2) and significant specific capacity (816 mAh gZn-1), indicating considerable potential as a bifunctional catalyst for electronic devices.

Fabrication of Two-Dimensional Homo-Bimetallic Porphyrin Framework Thin Films for Optimizing Nonlinear Optical Limiting

Developing efficient metal-organic framework (MOF) optical devices with tunable third-order nonlinear optical (NLO) properties is an important challenge for scientific research and practical application. Herein, 2D monometallic and hetero/homo-bimetallic porphyrin MOF thin films (ZnTCPP(M) M = H2, Fe, Zn) were fabricated using the liquid-phase epitaxial (LPE) layer-by-layer (LBL) method to investigate the metal substitution dependent third-order NLO behavior. The prepared homo-bimetallic ZnTCPP(Zn) thin film exhibited enhanced third-order NLO performance with a higher third-order nonlinear susceptibility of ∼4.21 × 10-7 esu compared to monometallic and hetero-bimetallic counterparts. Additionally, theoretical calculations were performed to complement the experimental findings and revealed that the enhanced NLO effect of the ZnTCPP(Zn) thin film is mainly attributed to the enhanced local excitation. These findings not only provide a comprehensive understanding of the relationship between metal types and the NLO behavior of porphyrin MOF thin films but also offer valuable insights into the design and optimization of NLO devices.

Solution-Processed Hydrogen-Bonded Organic Framework Nanofilms for High-Performance Resistive Memory Devices

The integration of hydrogen-bonded organic frameworks (HOFs) into electronic devices holds great promise due to their high crystallinity, intrinsic porosity, and easy regeneration. However, despite their potential, the utilization of HOFs in electronic devices remains largely unexplored, primarily due to the challenges associated with fabricating high-quality films. Herein, a controlled synthesis of HOF nanofilms with smooth surface, good crystallinity, and high orientation is achieved using a solution-processed approach. The memristors exhibit outstanding bipolar switching performance with a low set voltage of 0.86 V, excellent retention of 1.64 × 104 s, and operational endurance of 60 cycles. Additionally, these robust memristors display remarkable thermal stability, maintaining their performance even at elevated temperatures of up to 200 °C. More strikingly, scratched HOF films can be readily regenerated through a simple solvent rinsing process, enabling their reuse for the fabrication of new memristors, which is difficult to achieve with traditional resistive switching materials. Additionally, a switching mechanism based on the reversible formation and annihilation of conductive filaments is revealed. This work provides novel and invaluable insights that have a significant impact on advancing the widespread adoption of HOFs as active layers in electronic devices.