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Toxic acetone gas emissions and leakage are a potential threat to the environment and human health. Gas sensors founded on metal oxide semiconductors (MOS) have become an effective strategy for toxic gas detection with their mature process. In the present work, an efficient acetone gas sensor based on Au-modified ZnO porous nanofoam (Au/ZnO) is synthesized by polyvinylpyrrolidone-blowing followed by a calcination method. XRD and XPS spectra were utilized to investigate its structure, while SEM and TEM characterized its morphology. The gas sensitivity of the Au/ZnO sensors was investigated in a static test system. The results reveal that the gas-sensitive performance of porous ZnO toward the acetone can be enhanced by adjusting the loading ratio of noble Au nanoparticles. Specifically, the Au/ZnO sensor prepared by the Au loading ratio of 3.0% (Au/ZnO-3.0%) achieved a 100 ppm acetone gas response of 20.02 at the optimum working temperature of 275 °C. Additionally, a portable electronic device used a STM32 primary control chip to integrate the Au/ZnO-3.0% gas sensor with other modules to achieve the function of detecting and alarming toxic acetone gas. This work is of great significance for efficiently detecting and reducing acetone emissions. [ABSTRACT FROM AUTHOR]

The all-trans conformation (β -phase) possesses a significant impact on the piezoelectric polymer polyvinylidene fluoride (PVDF). Inducing more molecular chain [−CH2−CF2−] n to form all-trans conformation is one of the biggest obstacles for manufacturing high-performance piezoelectric sensing devices. Herein, the continuous vacuum technology is used to modulate the polarity of binary solvents by the proportion of the lower solvent. The regulated solvent forms a high dipole moment, an interaction between the dipole of β -phase and the dipole moment makes the phase reversal in PVDF. Fourier transform infrared spectroscopy, piezoelectric constant test and other characterization results show that when the weakly polar acetone and the strongly polar solvent DMF reach a ratio of 4:6, the pure PVDF film possesses high piezoelectricity (d 33 ∼ −44.8 pC N−1) and strong self-polarization. Additionally, the A4D6 device exhibits high sensitivity (S 1 = 0.182 V/N, 0.5 N ∼ 30 N), driven capability (0.49 mW m−2), and reliability during the electrical tests as a pressure device. This work provides an effective and cost-effective route of optimizing the solvent's polarity to improve the piezoelectric characteristics of the polymer. [ABSTRACT FROM AUTHOR]

Developing highly efficient, stable, and inexpensive electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is the premise of achieving large-scale water splitting. Here, NixFe1−xB prepared by a facile borothermal reduction in molten salt is a robust bifunctional electrocatalyst for overall water splitting. The NixFe1−xB electrocatalyst achieves a current density of 10 mA cm−2 at overpotentials of 63.5 mV for the HER and 282 mV for the OER in 1 M KOH electrolyte, respectively. Density functional theory (DFT) calculations suggest that the NixFe1−xB possesses a lower absolute value of H* adsorption free energy (‖ΔGH*‖) than the primitive FeB and NiB, which is beneficial to improve the HER activity. Two identical NixFe1−xB electrodes are combined to form an alkaline electrolyzer, which achieves a current density of 10 mA cm−2 at 1.57 V for overall water splitting. This work provides a strategy to develop highly efficient transition metal boride catalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

A series of silver nanoparticle-modified graphitic carbon nitride/N-doped TiO hybrids (Ag/g-CN/N-TiO or ACTs) were prepared by one-step in situ calcination process at 550 °C for 3 h in air atmosphere. The morphology, structure, and optical properties of ACTs with different Ag contents were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectra, and UV-vis diffuse reflectance spectroscopy. Ag nanoparticles with grain size of about 5 nm are anchored on the surface of ACTs. In UV-vis absorption test, a red-shift of light absorption edge and more visible light absorption (compared to N-TiO and g-CN/N-TiO) are observed for ACTs. Moreover, the dependence of photocatalytic activity on Ag contents was investigated, and ACTs-3 presents the highest photocatalytic activity as the optimal Ag content under visible light irradiation. Remarkably enhanced UV-visible light photoelectrochemical response was also confirmed for ACTs compared with TiO, N-TiO, and g-CN/N-TiO. Ag-decorated g-CN/N-TiO composites result in enhanced light absorption capacity and improved transfer of charge carriers, which prominently contribute to the improvement of photoactivity. This work demonstrates that Ag/g-CN/N-TiO is a promising photocatalytic material for organic pollutant degradation under visible light irradiation. [ABSTRACT FROM AUTHOR]

Herein, we report the successful formation of graphitic carbon nitride coated titanium oxide nanotube array thin films (g-C3N4/TiO2) via the facile thermal treatment of anodized Ti sheets over melamine. The proportion of C3N4 and TiO2 in the composite can be adjusted by changing the initial addition mass of melamine. The as-prepared samples are characterized by several techniques in order to understand the morphological, structural, compositional and optical properties. UV-vis absorption studies exhibit a remarkable red shift for the g-C3N4/TiO2 thin films as compared to the pristine TiO2 nanotubes. Importantly, the prepared composites exhibit an enhanced photocurrent and photo-potential under both UV-vis and visible light irradiation. Moreover, the observed maximum photo-conversion efficiency of the prepared composites is 1.59 times higher than that of the pristine TiO2 nanotubes. The optical and electrochemical impedance spectra analysis reveals that the better photo-electrochemical performance of the g-C3N4/TiO2 nanotubes is mainly due to the wider light absorption and reduced impedance compared to the bare TiO2 nanotube electrode. The presented work demonstrates a facile and simple method to fabricate g-C3N4/TiO2 nanotubes and clearly revealed that the introduction of g-C3N4 is a new and innovative approach to improve the photocurrent and photo-potential efficiencies of TiO2. [ABSTRACT FROM AUTHOR]