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Research on high‐efficiency and cost‐efficient catalysts for oxygen reduction reaction (ORR) is still a vital but challenging issue for commercializing metal–air batteries. Herein, a single‐molecule/atom hybrid catalyst is developed to boost the ORR, in which iron phthalocyanine molecules containing molecular Fe─N4 moieties couple with atomic Co─N4 sites on the surface of polyhedral carbon. Density functional theory calculations reveal that face‐to‐face laminated construction of Fe─N4 and Co─N4 in the hybrid catalyst can effectively modulate the electronic structure of active iron atoms and reduce the energy barrier of the rate‐determining step for ORR. As a result, this hybrid catalyst demonstrates excellent ORR performance, featuring a half‐wave potential of 0.904 V, a peak power density of 238.3 mW cm−2 for zinc–air battery, and outstanding electrocatalytic stability. This work offers a distinctive and robust molecular/atomic engineering approach to creating efficient electrocatalysts, advancing the fields of metal–air batteries. [ABSTRACT FROM AUTHOR]

Remote limb conditioning (RLC), performed by intermittent interruption of blood flow to a limb, triggers endogenous tolerance mechanisms and improves stroke outcomes. The underlying mechanism for the protective effect involves a shift of circulating monocytes to a Ly6CHigh proinflammatory subset in normal metabolic conditions. The current study investigates the effect of RLC on stroke outcomes in subjects with obesity, a vascular comorbidity. Compared to lean mice, obese stroke mice displayed significantly higher circulating monocytes (monocytosis), increased CD45High monocytes/macrophages infiltration to the injured brain, worse acute outcomes, and delayed recovery. Unlike lean mice, obese mice with RLC at 2 hours post-stroke failed to shift circulating monocytes to pro-inflammatory status and nullified RLC-induced functional benefit. The absence of the monocyte shift was also observed in splenocytes incubated with RLC serum from obese mice, while the shift was observed in the cultures with RLC serum from lean mice. These results showed that the alteration of monocytosis and subsets underlies negating RLC benefits in obese mice and suggest careful considerations of comorbidities at the time of RLC application for stroke therapy. [ABSTRACT FROM AUTHOR]

Chemiresistive gas sensors based on semiconducting metal oxides typically rely on noble metal catalysts to enhance their sensitivity and selectivity. However, noble metal catalysts have several drawbacks for practical utilization, including their high cost, their propensity for spontaneous agglomeration, and poisoning effects with certain types of gases. As such, in the interest of commercializing the chemiresistive gas sensor technology, we propose an alternative design for a noble-metal-free sensing material through the case study of Co-doped ceria (Co-CeO 2 ) catalysts embedded in a SnO 2 matrix. In this investigation, we utilized electrospinning and subsequent calcination to prepare Co-CeO 2 catalyst nanoparticles integrated with SnO 2 nanofibers (NFs) with uniform particle distribution and particle size regulation down to the sub-2 nm regime. The resulting Co-CeO 2 @SnO 2 NFs exhibited superior gas sensing characteristics toward isoprene (C 5 H 8 ) gas, a significant biomarker for monitoring the onset of various diseases through breath diagnostics. In particular, we identified that the Co-CeO 2 catalysts, owing to the transition metal doping, facilitated the spillover of chemisorbed oxygen species to the SnO 2 sensing body. This resulting in the sensor having a 27.4-fold higher response toward 5 ppm of C 5 H 8 (compared to pristine SnO 2 ), exceptionally high selectivity, and a low detection limit of 100 ppb. The sensor also exhibited high stability for prolonged response-recovery cycles, attesting to the strong anchoring of Co-CeO 2 catalysts in the SnO 2 matrix. Based on our findings, the transition metal-doped metal oxide catalysts, such as Co-CeO 2 , demonstrate strong potential to completely replace noble metal catalysts, thereby advancing the development of the commercially viable chemiresistive gas sensors free from noble metals, capable of detecting target gases at sub-ppm levels.

Light-activated chemiresistors offer a powerful approach to achieving lower-temperature gas sensing with unprecedented sensitivities. However, an incomplete understanding of how photoexcited charge carriers enhance sensitivity obstructs the rational design of high-performance sensors, impeding the practical utilization under commonly accessible light sources instead of ultraviolet or higher-energy sources. Here, a rational approach is presented to modulate the electronic properties of the parent metal oxide phase, exemplified by this model system of Bi-doped In 2 O 3 nanofibers decorated with Au nanoparticles (NPs) that exhibit superior NO 2 sensing performance. Bi doping introduces mid-gap energy levels into In 2 O 3 , promoting photoactivation even under visible blue light. Additionally, green-absorbing plasmonic Au NPs facilitate electron transfer across the heterojunction, extending the photoactive region toward the green light. It is revealed that the direct involvement of photogenerated charge carriers in gas adsorption and desorption processes is pivotal for enhancing gas sensing performance. Owing to the synergistic interplay between the Bi dopants and the Au NPs, the Au-Bi x In 2-x O 3 (x = 0.04) sensing layers attain impressive response values (R g /R a  = 104 at 0.6 ppm NO 2 ) under green light illumination and demonstrate practical viability through evaluation under simulated mixed-light conditions, all of which significantly outperforms previously reported visible light-activated NO 2 sensors., (© 2024 Wiley‐VCH GmbH.)