Photoacoustic spectroscopy (PAS) is an ultrasensitive method for gas sensing, which usually using a capacitive microphone as a signal detector. However, the electric nature of the microphone limits their applications in the circumstances with high temperature, electromagnetic interference (EMI), as well as explosive environments. Due to the uncharged and high-sensitivity characteristics, optical acoustic sensor is an ideal substitute in the circumstances above. Thus, all-optical PAS can get better applications in a harsh environment. In this paper, a brief review of all-optical PAS used in gas sensing with different optical acoustic sensing technologies is presented, such as intensity-modulated technology, fiber Bragg grating (FBG)-based technology, and interferometer-based technology. Besides, using a fiber-optic photoacoustic (PA) sensor would allow the realization of remote detection, in-situ detection, real-time monitoring, and multiplexed multi-point detection within a fiber-optic network. Finally, the advantages and limitations of these different technologies are discussed.

Hierarchical flower-like ZnO nanorods, net-like ZnO nanofibers and ZnO nanobulks have been successfully synthesized via a surfactant assisted hydrothemal method. The synthesized products were characterized by X-ray powder diffraction and field emission scanning electron microscopy, respectively. A possible growth mechanism of the various hierarchical ZnO nanostructures is discussed in detail. Gas sensors based on the as-prepared ZnO nanostructures were fabricated by screen-printing on a flat ceramic substrate. Furthermore, their gas sensing characteristics towards methane were systematically investigated. Methane is an important characteristic hydrocarbon contaminant found dissolved in power transformer oil as a result of faults. We find that the hierarchical flower-like ZnO nanorods and net-like ZnO nanofibers samples show higher gas response and lower operating temperature with rapid response-recovery time compared to those of sensors based on ZnO nanobulks. These results present a feasible way of exploring high performance sensing materials for on-site detection of characteristic fault gases dissolved in transformer oil.

The detection of partial discharge and analysis of the composition and content of sulfur hexafluoride SF₆ gas components are important to evaluate the operating state and insulation level of gas-insulated switchgear (GIS) equipment. This paper reported a novel sensing material made of pure ZnO and NiO-decorated ZnO nanoflowers which were synthesized by a facile and environment friendly hydrothermal process for the detection of SF₆ decomposition byproducts. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structural and morphological properties of the prepared gas-sensitive materials. Planar-type chemical gas sensors were fabricated and their gas sensing performances toward the SF₆ decomposition byproducts SO₂, SO₂F₂, and SOF₂ were systemically investigated. Interestingly, the sensing behaviors of the fabricated ZnO nanoflowers-based sensor to SO₂, SO₂F₂, and SOF₂ gases can be obviously enhanced in terms of lower optimal operating temperature, higher gas response and shorter response-recovery time by introducing NiO. Finally, a possible gas sensing mechanism for the formation of the p–n junctions between NiO and ZnO is proposed to explain the enhanced gas response. All results demonstrate a promising approach to fabricate high-performance gas sensors to detect SF₆ decomposition byproducts.

Raman spectroscopy is a powerful method for gas sensing but is limited by the inherently weak Raman effect. Due to the increase in intracavity laser power or improvement in spontaneous emission, cavity-enhanced technology is a useful enhancement method for the improvement of the limits of detection, which permits Raman spectroscopy to get better applications in gas sensing. In this article, a brief review of several cavity-enhanced technologies used in gas sensing by Raman spectroscopy is presented, the enhanced-cavities including multiple-pass cavities, Fabry–Perot cavities, laser cavities, and microcavities. Finally, the advantages and limitations of these different technologies are discussed.

The feasibility of aqueous zinc‐ion batteries for large‐scale energy storage is hindered by the inherent challenges of Zn anode. Drawing inspiration from cellular mechanisms governing metal ion and nutrient transport, erythritol is introduced, a zincophilic additive, into the ZnSO₄ electrolyte. This innovation stabilizes the Zn anode via chelation interactions between polysaccharides and Zn²⁺. Experimental tests in conjunction with theoretical calculation results verified that the erythritol additive can simultaneously regulate the solvation structure of hydrated Zn²⁺ and reconstruct the hydrogen bond network within the solution environment. Additionally, erythritol molecules preferentially adsorb onto the Zn anode, forming a dynamic protective layer. These modifications significantly mitigate undesirable side reactions, thus enhancing the Zn²⁺ transport and deposition behavior. Consequently, there is a notable increase in cumulative capacity, reaching 6000 mA h cm⁻² at a current density of 5 mA cm⁻². Specifically, a high average coulombic efficiency of 99.72% and long cycling stability of >500 cycles are obtained at 2 mA cm⁻² and 1 mA h cm⁻². Furthermore, full batteries comprised of MnO₂ cathode and Zn anode in an erythritol‐containing electrolyte deliver superior capacity retention. This work provides a strategy to promote the performance of Zn anodes toward practical applications.