Development of inexpensive and efficient oxygen evolution reaction (OER)catalysts in acidic environment is very challenging, but important for practical proton exchange membrane (PEM) water electrolyzers. Here we develop a molecular iron-nitrogen coordinated carbon nanofiber supported on electrochemically exfoliated graphene (FeN 4 /NF/EG) electrocatalyst through carbonizing the precursor composed of iron ions absorbed on polyaniline-electrodeposited EG. Benefitting from the unique 3D structure, the FeN 4 /NF/EG hybrid exhibits a low overpotential of ~294 mV at 10 mA cm -2 for the OER in This article is protected by copyright. All rights reserved.
5precursor was uniformly electrodeposited on EG surface that was constructed by electrochemical exfoliation of graphite (Figure S1). After soaking in iron nitrate solution, carbonization, and acid etching treatments, the precursor was in situ converted into FeN x /NF/EG catalyst, which is supported by Fourier-transform infrared spectroscopy (FTIR) results (Figure S2). We systematically explored the influence of annealing at different temperatures (800-1000 o C) affecting the OER activity. The optimized carbonization temperature was 900 o C (FeN x /NF/EG), which exhibited the best electrocatalytic performance for OER in acid (Figure S3-S4). Moreover, this synthesis method can be further This article is protected by copyright. All rights reserved. 13 support from U.S. DOE fuel cell technologies Offices. M. Qiu thanks the support of Self-determined Research Funds of CCNU from Colleges' Basic Research and Operation of MOE ( 23020205170456). This research was supported by Dr. Y. Hu (Yongfeng Hu) to provide valuable discussion about the XAS analysis.Received: ((will be filled by the editorial staff))Revised: ((will be filled by the editorial staff))
Carbapenem-resistant Klebsiella pneumoniae (CRKP) is emerging as a worldwide public health concern; however, the longterm molecular epidemiological surveillance of clinical CRKP in China is limited. We conducted a retrospective observational study (2008-2018) to assess the prevalence, susceptibility, risk factors and molecular epidemiology of clinical CRKP isolates. We found the prevalence of CRKP increased from 2.5%, 2008 to 15.8%, 2018. CRKP were significantly more frequent among hospitalized patients from ICU, and it was significantly more likely to be isolated from the capital city (Hangzhou) and the patients aged ≥60 years. Additionally, seasons and specimen types were associated with CRKP infections. The main CRKP sequence type (ST) was ST11, and bla KPC-2 was the most prevalent gene variant. Together these data reveal an increasing incidence and resistance trends among CRKP, especially the ST11-bla KPC-2-CRKP, in Zhejiang, during 2008-2018. Our findings are important for hospitals to limit its dissemination and optimize antibiotic administration.
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