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The van der Waals (vdW) heterojunctions of transition metal dichalcogenides (TMDCs) provide an advanced platform for interlayer exciton generation to detect the exceeding cutoff wavelengths of individual TMDCs. Herein, the first demonstration of high‐performance infrared (IR) photodetectors driven by interlayer excitons and based on HfS2/MoS2 vdW heterojunctions grown by chemical vapor deposition is presented. HfS2 exhibits selective growth only on MoS2, establishing a vertical heterojunction that effectively generates interlayer excitons. The synthesized HfS2/MoS2 vertical heterojunction with type‐II band alignment exhibits a low interlayer bandgap and a significantly large interface area, enabling highly efficient IR detection. Moreover, the built‐in potential in HfS2/MoS2 plays a pivotal role in the outstanding photoresponse by suppressing the dark current and providing gradient band bending for the interlayer exciton‐induced photocarriers to drift toward each electrode. The HfS2/MoS2 photodetector exhibits remarkable performance, achieving a detectivity (D*) of ≈7 × 1013 Jones at 1550 nm, D* of ≈2 × 1014 Jones at 980 nm, and fast response time of 60 µs, surpassing previously reported 2D photodetectors. Overall, the successful demonstration of a photodetector based on vdW epitaxial HfS2/MoS2 paves the way for the advancement of large‐scale high‐performance IR sensors. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) provide insight into the taste and aroma of milk. VOCs in milk are typically analyzed using headspace gas chromatography–mass spectrometry (GC‐MS). While static headspace GC‐MS is a simple and widely applicable analytical technique for the analysis of VOCs in various samples, it has not been frequently applied to milk samples. In this study, static headspace GC‐MS was used to compare the VOCs of three different brands of commercial milk. Three components were identified in the samples, that is, acetone, toluene, and 2‐heptanone, where the concentration ranges of acetone, toluene, and 2‐heptanone in the milk samples were 2.284–3.256, 0.028–0.178, and 0.014–0.020 μg/mL, respectively. A literature review found that all three components were previously reported in milk, while toluene and 2‐heptanone were newly identified using headspace GC‐MS in this study. [ABSTRACT FROM AUTHOR]

2D InSe is one of the semimetal chalcogenides that has been recently given attention thanks to its excellent electrical properties, such as high mobility near 1000 cm2 V−1 s−1 and moderate band gap of ≈1.26 eV suitable for IR detection. Here, high‐performance visible to near‐infrared (470–980 nm wavelength (λ)) photodetectors using surface‐doped InSe as a channel and few‐layer graphenes (FLG) as electrodes are reported, where the InSe top region is relatively p‐doped using AuCl3. The surface‐doped InSe photodetectors show outstanding performance, achieving a photoresponsivity (R) of ≈19 300 A W−1 and a detectivity (D*) of ≈3 × 1013 Jones at λ = 470 nm, and R of ≈7870 A W−1 and D* of ≈1.5 × 1013 Jones at λ = 980 nm, superior to previously reported 2D material‐based IR photodetectors operating without an applied gate bias. Surface doping using AuCl3 renders a band bending at the junction between the InSe surface and the top FLG contact, which facilitates electron‐hole pair separation and immediate photodetection. Multiple doped or undoped InSe photodetectors with different device structures are investigated, providing insight into the photodetection mechanism and optimizing performance. Encapsulation with hexagonal boron nitride dielectric also allows for 3‐month stability. [ABSTRACT FROM AUTHOR]

Flexible and transparent hybrid piezoelectric nanogenerators (PENGs) are prepared, based on vertical arrays of shape-modulated ZnO nanorods (ZnO-NRs) placed between two single-layer graphene sheets. A simple transfer printing method using polydimethylsiloxane (PDMS) stamps in conjunction with polyethylene terephthalate (PET) enables the fabrication of flexible stacked structures of ZnO-NRs/graphene/PDMS/PET, and the morphology of the ZnO-NRs is controlled by metallic additives during their hydrothermal synthesis. The hybrid PENGs are transparent and generated electrical power upon bending; the power output performance is dependent on the nanorod morphology with a net volume power density of 0.0513 mW mm-3 for Cd-doped ZnO-NRs, which is comparable to that of today's energy storage devices. The variation in output power is ascribed to the differences in the deformation modes of ZnO-NRs on bending because of the differences in their aspect ratios that are, in turn, controlled by the metallic additives; this suggests the possibility of customizing the power generation characteristics within a single material system. [ABSTRACT FROM AUTHOR]