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NO 2 – detection based on Au-Ni-Rh/LIG electrochemical sensor. [Display omitted] • Au, NiO, and Rh nanoparticles were deposited onto LIG by one-step electrodeposition. • DFT calculation confirmed the enhanced adsorption energy and electron transfer. • Three metals promoted the detection of nitrite in terms of catalysis and adsorption. • The developed sensor obtained a very low detection limit of 0.3 μM for nitrite. • This sensor can be used for portable determination of NO 2 – in real water samples. In this study, we employed a straightforward and rapid one-step electrodeposition method to enhance modify an Au/NiO/Rh composite on laser-induced graphene (LIG) for nitrite (NO 2 –) detection. We extensively characterized and tested the morphological composition and electrochemical properties of the electrode using scanning electron microscopy and other characterization techniques. To compare the electrochemical active surface areas of the electrode before and after modification, we conducted cyclic voltammetry experiments. Additionally, we confirmed the changes in electron transfer performance and adsorption energy of the modified electrode through by density functional theory calculations. The experimental results demonstrate that the combined modification of LIG with rhodium nanoparticles (RhNPs) and gold nanoparticles (AuNPs) improves electron transport ability at the electrode interface and enhances the electrode's electrocatalytic performance. The incorporation of nickel oxide (NiO) also provides a larger reaction area and more active sites for NO 2 – detection. The synergistic effects of these three modified components significantly enhance NO 2 – detection at the electrode, surpassing the performance of the bimetallic modified electrode. Under optimized experimental conditions, the sensor exhibits a linear range of 1 μmol/L to 1 mmol/L and a detection limit of 0.3 μmol/L. Furthermore, the sensor demonstrates excellent anti-interference and repeatability properties. We successfully applied the sensor for determination of NO 2 – in tap water, yielding satisfactory results. This research presents a promising strategy for the portable, sensitive, and in-situ detection of NO 2 – in water environments using metal-based electrochemical sensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The MoS 2 nanosheets grown on M@NDC (M = Co, Fe or CoFe alloy) by hydrothermal method. • The as-prepared M@NDC@MoS 2 hybrids display improved HER performance. • The CoFe@NDC@MoS 2 hybrid shows excellent performance and durability for HER. • The enhanced HER properties was explained by characterizations and DFT calculations. The design and synthesis of a highly active noble metal-free electrocatalyst for hydrogen evolution reaction (HER) from water splitting are crucial for renewable energy technologies. Herein, we report the growth of molybdenum disulfide (MoS 2) on N-doped carbon encapsulated metal particles (M@NDC@MoS 2 , where M = Co, Fe or CoFe alloy) as a highly active electrocatalyst for HER. The hierarchical MoS 2 nanosheets are grown on M@NDC using the hydrothermal method. Our results show that CoFe@NDC@MoS 2 hybrid spheres exhibit excellent HER performance with an overpotential of 64 mV at a current density of 10 mA cm−2 and a small Tafel slope of 45 mV dec-1. In addition, CoFe@NDC@MoS 2 hybrid spheres have good long-term stability and durability in acidic conditions. Besides, density functional theory (DFT) simulations of the proposed catalysts are performed and suggest that the superior catalytic activity of CoFe@NDC@MoS 2 is due to the optimal electron transfer from CoFe@NDC nanoparticles to MoS 2 nanosheets. This electron transfer facilitates H+ interaction and adsorption, leading to a decreased Gibbs free energy (ΔG H* ≈ 0.08 eV) and local work function on the surface, which consequently enhances the HER performance. [ABSTRACT FROM AUTHOR]