RESUMEN
The past decade has witnessed the great potential of Fe-based single-atom electrocatalysis in catalyzing oxygen reduction reaction (ORR). However, it remains a grand challenge to substantially improve their intrinsic activity and long-term stability in acidic electrolytes. Herein, we report a facile chemical vapor deposition strategy, by which high-density Fe atoms (3.97â wt%) are coordinated with square-planar para-positioned nitrogen and phosphorus atoms in a hierarchical carbon framework. The as-crafted atomically dispersed Fe catalyst (denoted Fe-SA/PNC) manifests an outstanding activity towards ORR over the entire pH range. Specifically, the half-wave potential of 0.92â V, 0.83â V, and 0.86â V vs. reversible hydrogen electrode (RHE) are attained in alkaline, neutral, and acidic electrolytes, respectively, representing the high performance among reported catalysts to date. Furthermore, after 30,000 durability cycles, the Fe-SA/PNC remains to be stable with no visible performance decay when tested in 0.1â M KOH and 0.5â M H2 SO4 , and only a minor negative shift of 40â mV detected in 0.1â M HClO4 , significantly outperforming commercial Pt/C counterpart. The coordination motif of Fe-SA/PNC is validated by density functional theory (DFT) calculations. This work provides atomic-level insight into improving the activity and stability of non-noble metal ORR catalysts, opening up an avenue to craft the desired single-atom electrocatalysts.
RESUMEN
The performance optimization of isolated atomically dispersed metal active sites is critical but challenging. Here, TiO2@Fe species-N-C catalysts with Fe atomic clusters (ACs) and satellite Fe-N4 active sites were fabricated to initiate peroxymonosulfate (PMS) oxidation reaction. The AC-induced charge redistribution of single atoms (SAs) was verified, thus strengthening the interaction between SAs and PMS. In detail, the incorporation of ACs optimized the HSO5- oxidation and SO5·- desorption steps, accelerating the reaction progress. As a result, the Vis/TiFeAS/PMS system rapidly eliminated 90.81% of 45 mg/L tetracycline (TC) in 10 min. The reaction process characterization suggested that PMS as an electron donor would transfer electron to Fe species in TiFeAS, generating 1O2. Subsequently, the hVB+ can induce the generation of electron-deficient Fe species, promoting the reaction circulation. This work provides a strategy to construct catalysts with multiple atom assembly-enabled composite active sites for high-efficiency PMS-based advanced oxidation processes (AOPs).
RESUMEN
Solid-state ionic conductors are compelling alternatives to liquid electrolytes in clean energy-harvesting and -storage technologies. The development of novel ionic conducting materials is one of the most critical challenges for next-generation energy technologies. Several advancements in design strategies, synthetic approaches, conducting properties, and underlying mechanisms for ionic conducting metal-organic frameworks (MOFs) have been made over the past five years; however, despite the recent, considerable expansion of related research fields, there remains a lack of systematic overviews. Here, an extensive introduction to ionic conducting performance for MOFs with different design strategies is provided, focusing primarily on ion mobility with the aid of hydrogen-bonding networks or solvated ionic charge. Furthermore, current theories on ion conducting mechanisms in different regimes are comprehensively summarized to provide an understanding of the underlying working principles in complex, realistic systems. Finally, challenges and future research directions at the forefront of ionic conducting MOF technologies are outlined.
RESUMEN
In this study, sulfamethoxazole served as the electron donor for microbial electrolysis cells. After 6â¯months of operation, the removal efficiencies of sulfamethoxazole in three microbial electrolysis cells were 77.60%, 87.55%, and 92.53% for a 3-day period and were directly proportional to the initial added concentrations. However, the removal efficiencies in the microbial electrolysis cells with open circuits and without microorganisms were only 51% and 8%, respectively. Higher sulfamethoxazole concentrations and sustained electrical stimulation caused faster bioelectrochemical reactions, thereby enhancing sulfamethoxazole degradation. Bacterial community analysis revealed that Proteobacteria and Synergistetes, which are the main functional phyla, proliferated with increased antibiotic concentrations. The qPCR results indicated that the copy numbers of antibiotic resistance genes and integrons in microbial electrolysis cell biofilms and effluents were distinctly lower than those in traditional biological treatment systems. Thus, the generation and dissemination of antibiotic resistance genes might be a diminished challenge in microbial electrolysis cells.
Asunto(s)
Antibacterianos , Sulfametoxazol , Bacterias , Farmacorresistencia Microbiana , Electrólisis , Aguas ResidualesRESUMEN
In this study, more than 85.1% of sulfamethoxazole (SMX) could be degraded within 60â¯h. The strengthening of microbial metabolisms and the sustainment of electrical stimulation contributed to the rapid removal of SMX in microbial fuel cells (MFCs). High-performance liquid chromatography identified that SMX could be thoroughly degraded into less harmful alcohols and methane after the MFC processing. In addition, the major role of Shewanella sp. and Geobacteria sp. in power generation, and the promotion of Alcaligenes, Pseudomonas and Achromobacter in SMX degradation have been demonstrated. Moreover, this study further proved that the copy numbers of targeted antibiotic resistance genes and integrons produced in MFCs were much lower than those found in conventional wastewater treatment plants; MFCs seem to be a promising alternative to reduce antibiotics in wastewater treatment and water purification.
Asunto(s)
Fuentes de Energía Bioeléctrica , Sulfametoxazol , Antibacterianos , Farmacorresistencia Microbiana , Aguas ResidualesRESUMEN
Objective To investigate the effect of laparoscopic ultrasonography assistance in minimally invasive surgery for uterine leiomyoma patients and provide scientific basis for reducing the recurrence rate of uterine leiomyoma. Methods 156 cases of uterine leiomyoma from January 2011 to June 2014 were divided into control group and observation group according to the digital table method, 78 cases in each. The control group were treated with conventional laparoscopic surgery, while the observation group with laparoscopic ultrasonography assistance, then compare the postoperative residue, recurrence in 12 months at different time points and the number of fibroids diameter, analyze the relationship between number of uterine muscle tumor and residual recurrence. Results There were no significant differences in operation time, blood loss, length of hospital stay and anal exhaust time between the two groups. The proportion of patients in the observation group and the recurrence rate within 12 months were significantly lower than those in the control group, the number of uterine leiomyomas in the observation group was significantly lower than that in the control group at 3 months, 6 months, 9 months and 12 months after operation. The patients in the two groups were followed up for 3 months and 6 months the maximum diameter of uterine leiomyoma was not statistically significant, the observation group 9 months and 12 months after the maximum diameter of uterine fibroids was significantly lower than the control group, and the difference was statistically significant; with the patient's uterine muscle the number of residual tumor and the recurrence rate were significantly increased. When the number of uterine leiomyomas was 10 or more, the residual rate was 100.0% and the recurrence rate was 80.0%. Conclusion Laparoscopic ultrasonography assistance in minimally invasive surgery for patients with uterine fibroids can effectively reduce the postoperative residual rate and recurrence rate, worthy of clinical promotion.