Hierarchical 2D/1D MOFs/electrospun ZIF-67 modified carbon nanofibers heterostructure electrode for high-performance asymmetric supercapacitor

In this paper, a 2 dimensional (2D) metal-organic frameworks (MOFs) nanosheets grown on 1D ZIF-67 modified carbon nanofibers (CNFs) was designed and fabricated with a hierarchical heterostructure. The hierarchical 2D/1D MOFs/CCNF offers rich electrochemical active sites and favorable ion/electron diffusion pathways. The synergistic effect of Co, CNFs and MOFs from heterostructures contributes to superb electrochemical activities. Benefiting from the hierarchical heterostructures optimized by the mass ratio of ZIF-67/PAN and CCNF/NiMOF as well as the type of substrates, CCNF-20@MOF showed a specific capacity of 361.50 C g-1 at 0.5 A g-1, whose charge storage mechanism is dominated by diffusion control. Meanwhile, a bamboo-derived carbon material (BBC) was designed in the solid-state asymmetric supercapacitor (CCNF-20@MOF//BBC). The device exhibited an energy density of 38.89 Wh kg-1 at the power density of 800.02 W kg-1 and excellent cycling stability, that exceed many MOFs based devices. Moreover, it could be successfully used for LED light-emitting, demonstrating a good application prospect. This work provides a feasible strategy for the improved performance of MOFs and CNFs based materials in the field of energy storage.

Self-Powered Nitrogen Dioxide Sensor Based on Pd-Decorated ZnO/MoSe2 Nanocomposite Driven by Triboelectric Nanogenerator

This paper introduces a high-performance self-powered nitrogen dioxide gas sensor based on Pd-modified ZnO/MoSe₂ nanocomposites. Poly(vinyl alcohol) (PVA) nanofibers were prepared by high-voltage electrospinning and tribological nanogenerators (TENGs) were designed. The output voltage of TENG and the performance of the generator at different frequencies were measured. The absolute value of the maximum positive and negative voltage exceeds 200 V. Then, the output voltage of a single ZnO thin-film sensor, Pd@ZnO thin-film sensor and Pd@ZnO/MoSe₂ thin-film sensor was tested by using the energy generated by TENG at 5 Hz, when the thin-film sensor was exposed to 1-50 ppm NO₂ gas. The experimental results showed that the sensing response of the Pd@ZnO/MoSe₂ thin-film sensor was higher than that of the single ZnO film sensor and Pd@ZnO thin-film sensor. The TENG-driven response rate of the Pd@ZnO/MoSe₂ sensor on exposure to 50 ppm NO₂ gas was 13.8. At the same time, the sensor had good repeatability and selectivity. The synthetic Pd@ZnO/MoSe₂ ternary nanocomposite was an ideal material for the NO₂ sensor, with excellent structure and performance.

UV-light-enhanced room temperature NO2 gas-sensing performances based on sulfur-doped graphitic carbon nitride nanoflakes

Two-dimensional graphitic carbon nitride (g-C3N4) has generated tremendous attention in room temperature (RT) gas-sensing applications because of its physicochemical characteristics.

Olivine-type cadmium germanate: a new sensing semiconductor for the detection of formaldehyde at the ppb level

In this study, for the first time, olivine-structured Cd2GeO4 was identified as an excellent formaldehyde sensing material, with a low detection limit of 60 ppb.

Sputtered SnO2/ZnO Heterostructures for Improved NO2 Gas Sensing Properties

A highly sensitive and selective NO2 gas sensor dependent on SnO2/ZnO heterostructures was fabricated using a sputtering process. The SnO2/ZnO heterostructure thin film samples were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Sensors fabricated with heterostructures attained higher gas response (S = 66.9) and quicker response-recovery (20 s, 45 s) characteristics at 100 °C operating temperature towards 100 ppm NO2 gas efficiently in comparison to sensors based on their mono-counterparts. The selectivity and stability of SnO2/ZnO heterostructures were studied. The more desirable sensing mechanism of SnO2/ZnO heterostructures towards NO2 was described in detail.

Construction of Ag3PO4/SnO2 Heterojunction on Carbon Cloth with Enhanced Visible Light Photocatalytic Degradation

In this study, the Ag3PO4/SnO2 heterojunction on carbon cloth (Ag3PO4/SnO2/CC) was successfully fabricated via a facile two-step process. The results showed that the Ag3PO4/SnO2/CC heterojunction exhibited a remarkable photocatalytic performance for the degradation of Rhodamine B (RhB) and methylene blue (MB), under visible light irradiation. The calculated k values for the degradation of RhB and MB over Ag3PO4/SnO2/CC are 0.04716 min−1 and 0.04916 min−1, which are higher than those calculated for the reactions over Ag3PO4/SnO2, Ag3PO4/CC and SnO2/CC, respectively. The enhanced photocatalytic activity could mainly be attributed to the improved separation efficiency of photogenerated electron-hole pairs, after the formation of the Ag3PO4/SnO2/CC heterojunction. Moreover, carbon cloth with a large specific surface area and excellent conductivity was used as the substrate, which helped to increase the contact area of dye solution with photocatalysts and the rapid transfer of photogenerated electrons. Notably, when compared with the powder catalyst, the catalysts supported on carbon cloth are easier to quickly recycle from the pollutant solution, thereby reducing the probability of recontamination.

Enhanced NO2 sensing performance of S-doped biomorphic SnO2 with increased active sites and charge transfer at room temperature

S-Doped biomorphic SnO₂ with active S-terminations and S–Sn–O chemical bonds has significantly improved gas sensing performance to NO₂ at room temperature.