Highly sensitive detection of H2S gas at low temperature based on ZnCo2O4 microtube sensors

Metal-Organic-Framework Derived Co-Mo Multimetal Oxide Semiconductors: Selective Trace-Level Hydrogen Sulfide Detection

The development of a highly selective and trace-level gas sensing platform for detecting hydrogen sulfide (H2S) remains a formidable challenge. To solve this problem, Co-Mo multimetal oxide semiconductors are rationally tailored by employing metal organic frameworks (MOFs) as self-sacrificial templates. The MOF-derived Co3O4/β-CoMoO4 based gas sensors displays high sensitivity (Rg/Ra = 22) to 10 ppm of H2S and ultralow limit of detection (10 ppb H2S). The formation of p-p heterojunction and multivalence states of Mo play a crucial role in electron transfer and oxygen adsorption. A sensor array constructed from four Co3O4/β-CoMoO4 materials with different Co/Mo ratios demonstrates a superior selective discrimination of H2S from other VOCs and malodorous gases by principal component analysis (PCA). Besides, a H2S gas sensing and alarming platform was designed for monitoring the environment contaminated with H2S. This finding provides a feasible approach for the discovery of highly efficient gas sensors to monitor environmental H2S concentration.

Deep Learning-Assisted Colorimetric/Electrical Dual-Sensing System for Ultrafast Detection of Hydrogen Sulfide

This study presents a colorimetric/electrical dual-sensing system (CEDS) for low-power, high-precision, adaptable, and real-time detection of hydrogen sulfide (H2S) gas. The lead acetate/poly(vinyl alcohol) (Pb(Ac)2/PVA) nanofiber film was transferred onto a polyethylene terephthalate (PET) flexible substrate by electrospinning to obtain colorimetric/electrical sensors. The CEDS was constructed to simultaneously record both the visual and electrical response of the sensor, and the improved Manhattan segmentation algorithm and deep neural network (DNN) were used as its intelligent algorithmic aids to achieve quantitative exposure to H2S. By exploring the mechanism of color change and resistance response of the sensor, a dual-sensitivity mechanism explanation model was proposed to verify that the system, as a dual-mode parallel system, can adequately solve the sensor redundancy problem. The results show that the CEDS can achieve a wide detection range of H2S from 0.1-100 ppm and identify the H2S concentration in 4 s at the fastest. The sensor can be stabilized for 180 days with excellent selectivity and a low limit of detection (LOD) to 0.1 ppm of H2S. In addition, the feasibility of the CEDS for measuring H2S levels in underground waterways was validated. This work provides a new method for adaptable, wide range of applications and low-power, high-precision H2S gas detection.

Waste to treasure: Electrocatalytic upcycling of n-valeraldehyde to octane by Zn-Co bimetallic oxide with atomic level cation defect

n-Valeraldehyde is widely used in organic synthesis field as an important intermediate and feedstock, which makes it a significant class of environmental pollutants. In view of the high poisonous and harmful of n-valeraldehyde to human health and ecological environment, it is important to develop green and sustainable technology to reduce the pollution of n-valeraldehyde. In this work, electrocatalytic n-valeraldehyde oxidation using Zn-Co bimetallic oxides was applied to control n-valeraldehyde contamination and highly valuable octane production. To further improve the performance of Zn-Co bimetallic oxides, atomic level Zn vacancies were created across the Zn-Co bimetallic oxides (dx-ZnCo2O4) by post-etching and oxygen vacancy filling methods. Electrochemical experiments results showed that dx-ZnCo2O4 owned a much higher octane yield (1193.4 µmol g-1 h-1) and octane selectivity (octane/butene ≈10). Theoretical calculations demonstrated that the introduction of atomic level Zn vacancies in Zn-Co bimetallic oxide changed the electronic distribution around O, Co and Zn atoms, resulted in an alteration in n-valeraldehyde adsorption sites from Co to Zn, reduced the formation barrier of key intermediate *C4H9 and facilitated the transfer of n-valeraldehyde to octane. This study provides a new idea for the development of high-performance electrocatalysts for controlling n-valeraldehyde pollution.

Highly Sensitive Room Temperature H2S Gas Sensor Based on the Nanocomposite of MoS2-ZnCo2O4

The stacking 2D materials, such as molybdenum disulfide (MoS2), are among the most promising candidates for detecting H2S gas. Herein, we designed a series of novel nanocomposites consisting of MoS2 and ZnCo2O4. These materials were synthesized via a simple hydrothermal method. The microstructure and morphology of nanocomposites were studied by different characteristics such as X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy. These nanocomposites were used as gas sensors, and the highest response (6.6) toward 10 ppm of H2S was detected by the gas sensor of MZCO-6 (having MoS2 contents 0.060 g) among all other tested sensors. The response value (Ra/Rg) was almost three times that of pure ZnCo2O4 (Ra/Rg = 2). In addition, the sensor of MZCO-6 exposed good selectivity, short response/recovery time (12/28 s), long-term stability (28 days), and a low detection limit (0.5 ppm) toward H2S gas at RT. The excellent performance of MZCO-6 may be attributed to some features of MoS2, such as stack structure, higher BET and surface area and active sites, a synergistic effect, etc. This simple fabrication sensor provides a novel idea for detecting H2S gas at RT.

A Potential Polycarbonyl Polyimide as Anode Material for Lithium-Ion Batteries

Organic polymers have been considered reliable candidates for lithium storage due to their high capacity and lack of volume expansion. Compared with other organic polymers, polyimide has become a very promising electrode material for lithium-ion batteries (LIBs) because of its easy synthesis, customizable structure and structural stability. A large number of studies have confirmed that the benzene ring structure of polyimide has strong lithium storage capacity as an anode material. Hence, we designed and synthesized polyimide organic polymer (PBPAQ) for the first time. The unique spherical flower structure of this material enhances the interaction between the electrode material and the electrolyte by increasing the contact area. The PBPAQ anode has a specific discharge capacity of 738 mAh g-1 after 100 cycles at 0.1 A g-1 . The excellent lithium storage performance of this material laid a foundation for the research of the anode of LIBs in the future.