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Food safety, particularly concerning foods contaminated by toxic chemicals, has emerged as a pervasive societal concern. The prevalence of food contaminants has spurred both scientific communities and industries to develop highly sensitive and selective sensors for rapid and precise food authentication. Noble metal nanoparticles (NPs) have garnered significant attention in this regard due to their exceptional properties, including high sensitivity, selectivity, stability, target binding affinity, and versatility for modification to detect specific contaminants. Moreover, the readout of such sensors is relatively straightforward, as their resulting color change can be observed with the naked eye. This Review aims to delve into the current strategies involving various noble metal NPs as colorimetric nanosensors in food safety monitoring applications. It begins by elucidating their working principles, encompassing localized surface plasmon resonance (LSPR), enzyme-based approaches, and other methodologies. Subsequently, the material properties of commonly utilized noble metal NPs, including those of gold, silver, palladium, platinum, and copper, are meticulously examined, providing comprehensive overviews of the benefits and drawbacks associated with each material. Furthermore, this Review summarizes the latest use cases of noble metal NPs in diverse food safety monitoring applications, ranging from the detection of heavy metal contaminants to veterinary and pesticide drug residues and foodborne pathogens. Lastly, it addresses the remaining challenges in this field and proposes feasible solutions, offering insights into future research directions. [ABSTRACT FROM AUTHOR]

Discovering sources of transition metals, such as Ni, Co, and Mn, has become crucial due to their broad applicability, particularly as electrocatalysts for the oxygen evolution reaction (OER). Upcycled spent batteries have emerged as alternatives for transition metal sources for the OER electrocatalysts. In this work, Ni–Co–Mn oxalates were extracted from the spent LiNixCoyMnzO2 (NCM) cathode of lithium-ion batteries. The extracted oxalates were further processed via ball milling as a rapid and scalable mechanochemical route to engineer their structures. After calcination, Ni–Co–Mn oxides with nanosized granules on the surface that mainly consist of MnCo2O4 were obtained. With a correlation of morphology and trimetallic oxide formation with the OER catalytic performance, Ni–Co–Mn oxides exhibit OER overpotentials of 367 and 732 mV in alkaline and neutral media, respectively, showing OER catalytic activity in a wide pH range. The results indicate that ball milling can induce particle size reduction and bond formation between metals to facilitate mixed-metal oxide formation. Furthermore, the resulting material is also applicable as the catalyst in the air cathode of Zn-air batteries, where the battery achieved a power density of 85.42 mW cm–2 and 100 h of cycling stability, showing comparability with a battery with a Pt/C–Ir/C catalyst. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2), a promising two‐dimensional photothermal material, possesses the capability to convert solar irradiation into thermal energy. This conversion is beneficial for processes like wastewater treatment and seawater desalination. Nevertheless, the influence of the surface chemical properties of MoS2, particularly its wettability, on the evaporation rate of water confined to the surface remains unexplored. In our study, we demonstrate that the wettability degree of MoS2 significantly influences its water evaporation rate performance. Interestingly, this parameter can be simply and accurately modulated by altering the synthesis time of MoS2. We synthesized MoS2 via a simple hydrothermal method at three different durations: 16, 20, and 24 h, at 200°C. Subsequently, we impregnated the resultant MoS2 onto air‐laid paper (ALP), forming a solar‐driven evaporator system. We found that the MoS2 nanosheets synthesized within the shortest duration (MoS2‐16 h) exhibited the highest evaporation rate of 1.77 kg m−2 h−1, along with 92% energy efficiency. MoS2‐16 h resulted in MoS2 rich in defects, featuring the largest surface area and the smallest contact angle. The hydrophilic areas of MoS2‐16 h facilitated the continuous diffusion of water molecules through defect sites, treating them as contact lines. Additionally, the expansive surface area introduced a larger region for light absorption, enhancing water‐solid interactions. The presence of molybdenum oxide on the surface of the nanosheet system also contributed to superior wettability behavior. Notably, all the tested MoS2/ALP systems in this study displayed excellent performance in salt rejection and heavy metal ion concentration reduction. [ABSTRACT FROM AUTHOR]

ZnO-based photoanodes absorb a limited spectrum of light, and their photogenerated electrons and holes combine easily. Such features limit their photoelectrochemical activity. Herein, we report the synthesis of ternary heterostructures comprising ZnO nanorods (NRs) and ZnS nanoparticles wrapped in MoS2 nanosheets (ZnO/ZnS/MoS2, ZSM) directly grown on a substrate by a low-cost hydrothermal route and their performance as anodes for photoelectrochemical water splitting. The ZSM heterostructures exhibit a sixfold photocurrent density of 0.72 mA cm–2, a fourfold maximum applied bias photon-to-current efficiency of 0.28% compared to bare ZnO NRs, and excellent photostability. These improvements in the overall photoelectrochemical activity are due to enhanced light absorption in the visible light range, higher surface active sites, and efficient charge separation enabled by the introduction of a ZnS/MOS2 coating. Our study demonstrates an alternative architecture design of ternary heterostructures with increased photoelectrochemical activity. In general, this approach of constructing a double heterojunction can also be extended to other materials with similar architectures. [ABSTRACT FROM AUTHOR]

Nanoplasmonic sensors typically comprise arrangements of noble metal nanoparticles on a dielectric support. Thus, they are intrinsically characterized by surface topography with corrugations at the 10-100 nm length scale. While irrelevant in some bio- and chemosensing applications, it is also to be expected that the surface topography significantly influences the interaction between solids, fluids, nanoparticles and (bio)molecules, and the nanoplasmonic sensor surface. To address this issue, we present a wafer-scale nanolithography-based fabrication approach for high-temperature compatible, chemically inert, topographically flat, and laterally homogeneous nanoplasmonic sensor chips. We demonstrate their sensing performance on three different examples, for which we also carry out a direct comparison with a traditional nanoplasmonic sensor with representative surface corrugation. Specifically, we (i) quantify the film-thickness dependence of the glass transition temperature in poly(methyl metacrylate) thin films, (ii) characterize the adsorption and specific binding kinetics of the avidin-biotinylated bovine serum albumin protein system, and (iii) analyze supported lipid bilayer formation on SiO 2 surfaces.