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Fluoride (iF) is an inorganic element commonly present in groundwater in central Mexico and is considered a health risk when it exceeds the Mexican drinking water standard of 1.5 mg/L. Prolonged exposure to iF can cause various adverse health effects, such as dental fluorosis and neurological effects, particularly in children. A rapid and cost-effective strategy to identify possible areas where the resident population may be at risk of exposure to this contaminant is the health risk estimation methodology of the Pan American Health Organization (PAHO). The aim of this study was to estimate the environmental risk of iF exposure in residents of Jerez, Zacatecas, Mexico, and subsequently construct risk maps to identify areas of the city where there is a higher risk of exposure. Fifty-five tap water samples were collected from households to determine iF concentrations using the ion-selective electrode method. Based on these environmental values, the hazard quotient (HQ) was estimated following the health risk estimation methodology. Subsequently, risk maps were generated from these values to visualize the spatial distribution of high-risk areas within the city. The iF concentrations in tap water ranged from 1.3 to 7.3 mg/L (ppm), with only one sample below the standard of 1.5 mg/L. We estimated HQ values ranging from 0.63 to 3.73. Exposure to iF in tap water is a health problem that must be addressed, necessitating risk communication actions that enable the population to safeguard its health through simple measures, thereby avoiding future health costs. [ABSTRACT FROM AUTHOR]

Simultaneously increasing the activity and stability of the transition metal-based catalysts is critical for nonprecious metal catalysts toward oxygen reduction reaction (ORR). Herein, FeCo alloy nanoparticles encapsulated in nitrogen-doped carbon (NC) materials with surface-dangling M-Nx active sites were fabricated, and the corresponding electrocatalytic performance was carefully investigated toward ORR in both alkaline and acid media. The coexistence of M-Nx active species (Co5.47N or FeN0.0324) and FeCo alloy makes the ORR reactivity strongly enhanced compared to the counterparts with only M-Nx or FeCo species. Density functional theory calculations clearly reveal that the synergistic effect between FeCo, Fe-Nx, and NC can induce the hybridization effect between d orbitals of Fe/Co and p orbitals of N/C atoms, and thus favor the desorption of *OH intermediates. Therefore, the FeN0.0324-FeCo@NC nanocatalyst with abundant mesopores and macropores shows enhanced electrocatalytic performance in both media (E1/2 are 0.86 and 0.74 V, respectively). [ABSTRACT FROM AUTHOR]

Heterostructured non-precious metal phosphides have attracted increasing attention in the development of high-performance catalysts for hydrogen evolution reaction (HER), particularly in acidic media. Herein, a catalyst composed of ternary Ni5P4-NiP2-Ni2P nanocomposites and N-doped carbon nanotubes/carbon particulates (Ni5P4-NiP2-Ni2P/NC) was prepared from a Ni-containing hybrid precursor through approaches of a successive carbonization and phosphating reaction. Benefiting from the synergistic effect from three-component nickel phosphides and the support role of porous carbon network, the Ni5P4-NiP2-Ni2P/N-doped carbon catalyst presents the promising HER performance with overpotentials of 168 and 202 mV at the current density of 10 mA cm−2 and Tafel slopes of 69.0 and 74 mV dec−1 in both acidic and alkaline solutions, respectively, which surpasses the Ni2P/N-doped carbon counterpart. This work provides an effective strategy for the preparation and development of highly efficient HER non-precious metal electrocatalysts by creating heterostructure in acidic and alkaline media. [ABSTRACT FROM AUTHOR]

Abstract: Improving the efficiency of Pt‐based oxygen reduction reaction (ORR) catalysts while also reducing costs remains an important challenge in energy research. To this end, we synthesized highly stable and active carbon‐supported Mo‐doped PtCu (Mo‐PtCu/C) nanoparticles (NPs) from readily available precursors in a facile one‐pot reaction. Mo‐PtCu/C displays two‐to‐fourfold‐higher ORR half‐cell kinetics than reference PtCu/C and Pt/C materials, a trend that was confirmed in proof‐of‐concept experiments by using a H2/O2 microlaminar fuel cell. This Mo‐induced activity increase mirrors observations for Mo‐PtNi/C NPs and possibly suggests an emerging trend. Electrochemical‐accelerated stability tests revealed that dealloying was greatly reduced in Mo‐PtCu/C in contrast to the binary alloys PtCu/C and PtMo/C. Supporting DFT studies suggested that the exceptional stability of Mo‐PtCu could be attributed to oxidative resistance of the Mo‐doped atoms. Furthermore, our calculations revealed that oxygen could induce segregation of Mo to the catalytic surface, at which it effected beneficial changes to the surface oxygen adsorption energetics in the context of the Sabatier principle. [ABSTRACT FROM AUTHOR]

The Pt-M 2 O 3 /C (M = Y and Gd) catalysts were synthesized via carbonyl chemical route, and heat-treated at 300 °C. Both catalysts are nanoparticulated with a face-centered cubic ( fcc ) structure with no secondary phase present as revealed by X-ray diffraction (XRD) patterns similar to Pt/C, generated in the same way. Data analyses of Pt-M 2 O 3 /C XRD patterns via the Williamson–Hall method were performed. The stacking fault, and micro-strain values increased with respect to Pt/C catalyst. The transmission electron microscopy (TEM) further revealed that nano-particles are homogeneously dispersed in both Pt/C and Pt-M 2 O 3 /C (M = Y and Gd). The mean particle size is close, ca. 3.4 nm for Pt/C, ca. 4.1 nm for Pt-Y 2 O 3 /C and ca. 3.6 nm for Pt-Gd 2 O 3 /C sample. Although the surface electrochemical studies (cyclic and CO-stripping voltammograms) showed similar Pt surface behavior, the kinetics of oxygen reduction reaction (ORR) on Pt-M 2 O 3 /C (M = Y and Gd) catalysts was higher than the homemade Pt/C and commercial Pt/C catalysts (20 wt. %, Johnson Matthey). After 6000 potential cycles (0.6–1.0 V vs. RHE) of accelerated stability test (AST), the remaining Pt active surface (based on hydrogen underpotential deposition region) and kinetic current density (at 0.9 V vs. RHE) in Pt-M 2 O 3 /C (M = Y and Gd) catalysts were higher than the reference Pt/C, and commercial Pt/C catalysts. These findings assess the positive effect of M 2 O 3 (M = Y and Gd) in improving the activity and stability of Pt NPs towards ORR. [ABSTRACT FROM AUTHOR]