The design of active, selective, and stable CO2 reduction electrocatalysts is still challenging. A series of atomically dispersed Co catalysts with different nitrogen coordination numbers were ...prepared and their CO2 electroreduction catalytic performance was explored. The best catalyst, atomically dispersed Co with two‐coordinate nitrogen atoms, achieves both high selectivity and superior activity with 94 % CO formation Faradaic efficiency and a current density of 18.1 mA cm−2 at an overpotential of 520 mV. The CO formation turnover frequency reaches a record value of 18 200 h−1, surpassing most reported metal‐based catalysts under comparable conditions. Our experimental and theoretical results demonstrate that lower a coordination number facilitates activation of CO2 to the CO2.− intermediate and hence enhances CO2 electroreduction activity.
A remarkable carbon dioxide electroreduction catalytic performance with superior activity and high selectivity was achieved on atomically dispersed Co sites through coordination environment regulating. First step in picture: C–N fragments, 1000 °C; second step: NH3 treatment.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Single-atom catalysts often exhibit unexpected catalytic activity for many important chemical reactions because of their unique electronic and geometric structures with respect to their bulk ...counterparts. Herein we adopt metal–organic frameworks (MOFs) to assist the preparation of a catalyst containing single Ni sites for efficient electroreduction of CO2. The synthesis is based on ionic exchange between Zn nodes and adsorbed Ni ions within the cavities of the MOF. This single-atom catalyst exhibited an excellent turnover frequency for electroreduction of CO2 (5273 h–1), with a Faradaic efficiency for CO production of over 71.9% and a current density of 10.48 mA cm–2 at an overpotential of 0.89 V. Our findings present some guidelines for the rational design and accurate modulation of nanostructured catalysts at the atomic scale.
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IJS, KILJ, NUK, PNG, UL, UM
Single-atom metal catalysts have sparked tremendous attention, but direct transformation of cheap and easily obtainable bulk metal oxide into single atoms is still a great challenge. Here we report a ...facile and versatile gas-transport strategy to synthesize isolated single-atom copper sites (Cu ISAS/NC) catalyst at gram levels. Commercial copper (I) oxide powder is sublimated as mobile vapor at nearly melting temperature (1500 K) and subsequently can be trapped and reduced by the defect-rich nitrogen-doped carbon (NC), forming the isolated copper sites catalyst. Strikingly, this thermally stable Cu ISAS/NC, which is obtained above 1270 K, delivers excellent oxygen reduction performance possessing a recorded half-wave potential of 0.92 V vs RHE among other Cu-based electrocatalysts. By varying metal oxide precursors, we demonstrate the universal synthesis of different metal single atoms anchored on NC materials (M ISAS/NC, where M refers to Mo and Sn). This strategy is readily scalable and the as-prepared sintering-resistant M ISAS/NC catalysts hold great potential in high-temperature applications.
Herein, we construct a novel electrocatalyst with Fe–Co dual sites embedded in N-doped carbon nanotubes ((Fe,Co)/CNT), which exhibits inimitable advantages towards the oxygen reduction reaction. The ...electrocatalyst shows state-of-the-art ORR performance with an admirable onset potential (
E
onset
, 1.15 V
vs.
1.05 V) and half-wave potential (
E
1/2
, 0.954 V
vs.
0.842 V), outperforming those of the commercial Pt/C. The ORR test reveals that the performance of the (Fe,Co)/CNT is superior to most of the reported non-precious catalysts in alkaline electrolytes. Furthermore, when employed as a cathode catalyst in a Zn–air battery, the (Fe,Co)/CNT exhibits high voltages of 1.31 V and 1.23 V at discharge current densities of 20 mA cm
−2
and 50 mA cm
−2
, respectively. In addition, the power density and the specific energy density reach 260 mW cm
−2
and 870 W h kg
Zn
−1
. We discover that the Fe–Co dual sites embedded in N-doped porous carbon are beneficial for the activation of oxygen by weakening the OO bonds.
Two‐inch‐sized perovskite crystals, CH3NH3PbX3 (X=I, Br, Cl), with high crystalline quality are prepared by a solution‐grown strategy. The availability of large perovskite crystals is expected to ...transform its broad applications in photovoltaics, optoelectronics, lasers, photodetectors, LEDs, etc., just as crystalline silicon has done in revolutionizing the modern electronics and photovoltaic industries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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•Soil respiration in BSC-dominated areas was suppressed under warmer conditions.•The inhibited soil respiration by warming was greater on the moss than lichen crust.•Soil respiration ...in BSC-dominated areas was significantly induced by rainfall pulses.•Diel hysteresis between soil respiration and temperature was modified by rainfall.
Biological soil crusts (BSCs) across desert ecosystems play an important role in modulating terrestrial carbon cycles. Global warming and changes in precipitation patterns are expected to be important triggers for biological activity in BSC-dominated desert ecosystems. Therefore, it is crucial to study the effects of warming and rainfall pulses on soil respiration dynamics at BSC-dominated microsites to predict terrestrial carbon cycling under climate change. In this study, soil respiration rates were monitored continuously during three types of natural precipitation events in lichen-dominated and moss-dominated crusts in both control and warming treatments. Our results revealed that soil respiration was inhibited in BSC-dominated microsites in the warming treatment because of reduced soil water content induced by the warmer conditions, and that the extent of inhibition was lower in the lichen-dominated crusts than in the moss-dominated crusts. During all the precipitation events, soil respiration rates were significantly increased by rainfall pulses and gradually declined thereafter. Over the daily cycle, the clockwise diel hysteresis loop between soil respiration and soil temperature was modified by soil water availability, which was affected by the magnitude of rainfall pulses. Moreover, the effect of photosynthetically active radiation and the mismatch between the depth of carbon dioxide (CO2) production and soil temperature measurement may have contributed to the diel hysteresis pattern. Our results indicated that warming and different types of precipitation events in BSC-dominated desert ecosystems impact soil carbon release through changes in the magnitude of soil respiration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Developing a facile route to access active and well-defined single atom sites catalysts has been a major area of focus for single atoms catalysts (SACs). Herein, we demonstrate a simple approach to ...generate atomically dispersed platinum via a thermal emitting method using bulk Pt metal as a precursor, significantly simplifying synthesis routes and minimizing synthesis costs. The ammonia produced by pyrolysis of Dicyandiamide can coordinate with platinum atoms by strong coordination effect. Then, the volatile Pt(NH3) x can be anchored onto the surface of defective graphene. The as-prepared Pt SAs/DG exhibits high activity for the electrochemical hydrogen evolution reaction and selective oxidation of various organosilanes. This viable thermal emitting strategy can also be applied to other single metal atoms, for example, gold and palladium. Our findings provide an enabling and versatile platform for facile accessing SACs toward many industrial important reactions.
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IJS, KILJ, NUK, PNG, UL, UM
Metal sulfide based materials as photocatalysts for energy conversion are essential to produce value-added chemical fuels, but their intrinsically slow carrier dynamics and low activity are yet to be ...resolved. Herein, we developed a unique heterogeneously nanostructured ZnIn
2
S
4
-CdS heterostructure that involves zero-dimensional (0D) CdS quantum dots uniformly confined on three-dimensional (3D) ZnIn
2
S
4
nanoflowers, which achieves an excellent catalytic performance of CO
2
photoconversion under visible-light irradiation. The obtained hierarchical heterostructure can significantly enhance the light harvesting, shorten the migration distance of carriers, and obviously accelerate the transport of electrons. As evidenced by the ultrafast transient absorption spectroscopy, the formed interface can effectively facilitate charge separation and transport. This work opens up a new avenue to carefully design the elaborate heterostructures for achieving optimal charge separation efficiency by lowering interfacial kinetic barriers and energy losses at the interface.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Electroencephalogram (EEG) based seizure subtype classification is very important in clinical diagnostics. Source-free domain adaptation (SFDA) uses a pre-trained source model, instead of the source ...data, for privacy-preserving transfer learning. SFDA is useful in seizure subtype classification, which can protect the privacy of the source patients, while reducing the amount of labeled calibration data for a new patient. This paper introduces semi-supervised transfer boosting (SS-TrBoosting), a boosting-based SFDA approach for seizure subtype classification. We further extend it to unsupervised transfer boosting (U-TrBoosting) for unsupervised SFDA, i.e., the new patient does not need any labeled EEG data. Experiments on three public seizure datasets demonstrated that SS-TrBoosting and U-TrBoosting outperformed multiple classical and state-of-the-art machine learning approaches in cross-dataset/cross-patient seizure subtype classification.
The impact of statin use on the survival of esophageal cancer patients remains unclear now. The aim of this study was to identify the relationship between statin use and the long-term survival of ...esophageal cancer patients.
The PubMed, EMBASE, and Web of Science databases were searched up to August 20, 2022, for relevant studies. The endpoints included overall survival (OS), cancer-specific survival (CSS), recurrence-free survival, and hazard ratios (HRs) with corresponding 95% confidence intervals (CIs) were pooled to assess the association between statin use and the prognosis of esophageal cancer patients. Subgroup analysis based on the pathological type (adenocarcinoma vs squamous cell carcinoma), dose of statin use and tumor stage (tumor-node-metastasis I-III vs IV) was further performed. All statistical analyses were conducted using STATA 12.0 software.
A total of 7 retrospective studies involving 25,711 participants were included in this meta-analysis. The pooled results indicated that statin use was significantly associated with improved OS (HR = 0.80, 95% CI: 0.74-0.87, P < .001), CSS (HR = 0.77, 95% CI: 0.74-0.89, P < .001), and recurrence-free survival (HR = 0.38, 95% CI: 0.16-0.87, P = .022). Furthermore, subgroup analysis stratified by the pathological type, dose of statin use and tumor stage for OS and CSS showed similar results and indicated the protective role of statin use in the prognosis of esophageal cancer patients.
Statin use is significantly associated with improved long-term survival of esophageal cancer patients and might serve as a promising prognostic indicator in esophageal cancer. However, more prospective high-quality studies are still needed to verify our findings.
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