While
surface strain engineering in shaped and bimetallic nanostructures
offers additional variables for manoeuvring the catalysis, manipulating
isotropic strain distributions in nanostructures remains a great challenge
to reach higher tiers of the catalyst’s design. Herein, we
report an efficient approach to construct a unique class of core/shell
palladium–lead (Pd–Pb)/Pd nanosheets (NSs) and nanocubes
(NCs) with homogeneous tensile strain along [001] on both the top-Pd
and edge-Pd surfaces for boosting oxygen reduction reaction (ORR).
These core/shell Pd–Pb/Pd NSs and Pd–Pb/Pd NCs exhibit
over 160% and 140% increases in mass activity and over 114% and 98%
increases in specific activity when compared with these unshelled
counterparts, respectively. Especially, the Pd3Pb/Pd NSs
show the ORR mass and specific activities of 0.57 A/mgPd and 1.31 mA/cm2 at 0.90 V versus reversible hydrogen
electrode, which are 8.8 (6.5) and 9.4 (9.8) times higher than those
of the commercial Pd/C (Pt/C), respectively. The valence band photoemission
spectra and first-principles calculations collectively show that the
tensile strained Pd shell results in an upshift of the d-band-center
of Pd, weakening the chemisorption of oxygenated species due to the
contribution of the antibonding orbital. In addition, the Pd3Pb/Pd NSs and NCs with intermetallic core and homogeneous few layers
of Pd shell can sustain at least 20 000 potential cycles with
negligible activity decay and composition changes. The present work
provides a new direction for the design of highly active and stable
catalysts for fuel cells and beyond.
Since photocatalytic N2 to NH3 is
a kinetically complex and multielectron reaction, designing efficient
materials to fix N2 is highly essential. Herein, we reported
that simultaneously introducing oxygen vacancy and doping Fe into
BiOCl nanosheets (NSs) can greatly boost the photocatalytic N2 fixation. BiOCl NSs-Fe-5% exhibit the maximum NH3 generation rate of 1.022 mmol g–1 h–1 and durable stability after successive cycling, being one of the
best photocatalysts for N2 fixation. This work demonstrates
a promising strategy to design efficient photocatalysts for N2 fixation, holding great significance for extensions to other
material systems.
The electroreduction of small molecules to high value‐added chemicals is considered as a promising way toward the capture and utilization of atmospheric small molecules. Discovering cheap and efficient electrocatalysts with simultaneously high activity, selectivity, durability, and even universality is desirable yet challenging. Herein, it is demonstrated that Bi2Te3 nanoplates (NPs), cheap and noble‐metal‐free electrocatalysts, can be adopted as highly universal and robust electrocatalysts, which can efficiently reduce small molecules (O2, CO2, and N2) into targeted products simultaneously. They can achieve excellent activity, selectivity and durability for the oxygen reduction reaction with almost 100% H2O2 selectivity, the CO2 reduction reaction with up to 90% Faradaic efficiency (FE) of HCOOH, and the nitrogen reduction reaction with 7.9% FE of NH3. After electrochemical activation, an obvious Te dissolution happens on the Bi2Te3 NPs, creating lots of Te vacancies in the activated Bi2Te3 NPs. Theoretical calculations reveal that the Te vacancies can modulate the electronic structures of Bi and Te. Such a highly electroactive surface with a strong preference in supplying electrons for the universal reduction reactions improves the electrocatalytic performance of Bi2Te3. The work demonstrates a new class of cheap and versatile catalysts for the electrochemical reduction of small molecules with potential practical applications.
Diabetic cardiomyopathy (DCM) is associated with a greater risk of mortality in patients with diabetes mellitus. Currently, no specific treatment has been suggested for DCM treatment. This study demonstrated that myricetin (M) attenuated DCM-associated cardiac injury in mice subjected to streptozotocin (SZT) and in neonatal rat cardiomyocytes (NRCM) challenged with high glucose. In vivo investigation demonstrated 6 months of M treatment (200 mg/kg/d) significantly alleviated cardiac hypertrophy, apoptosis, and interstitial fibrosis. Mechanically, M treatment significantly increased the activity of Nrf2/HO-1 pathway, strengthening antioxidative stress capacity evidenced by reversed activities of GPx and SOD, and decreased MDA production. M treatment also inhibited IκBα/NF-κB pathway, resulting in reduced secretion of inflammation cytokines including IL-1β, TNF-α, and IL-6. Besides, the TGFβ/Smad3 signaling was also blunted in DCM mice treated with M. These beneficial effects of M treatment protected cardiomyocytes from apoptosis as shown by decreased TUNEL-positive nucleus, c-caspase 3, and Bax. Similar effects of M treatment could be reproduced in NRCM treated with high glucose. Furthermore, through silencing Nrf2 in NRCM, we found that the regulation of IκBα/NFκB by M was independent on its function on Nrf2. Thus, we concluded that M possesses potential protective effects on DCM through inhibiting IκBα/NFκB and enhancing Nrf2/HO-1.
Sepsis induced myocardial dysfunction (SIMD) is a common complication and leads to an increased mortality. SIMD is closely related to inflammation and oxidative stress. Myricetin exhibits strong capacities of anti-inflammation and anti-oxidative stress, but its pharmacological effects for lipopolysaccharide (LPS) induced cardiac injury remains undefined. This study aimed to explore whether myricetin was efficient to alleviate SIMD in mice and neonatal rat cardiomyocytes injury. Mice administrated with myricetin (100 mg/kg, po, bid) or vehicle groups were challenged with LPS (10 mg/kg, ip), and cardiac functions examined by echocardiography after 12 hr LPS exposure. LPS markedly impaired mouse cardiac functions, which were significantly attenuated by myricetin administration. Myricetin significantly reduced the production of inflammatory cytokines both in serum and cardiac tissue. Myricetin could inhibit the nuclear translocation of p65, degradation of IκBα, and cellular apoptosis in vivo and in vitro. Myricetin also prevented overexpression of iNOS and reduction of oxidoreductase (SOD and GPx) activity. Besides, Myricetin treatment could attenuate production of inflammatory cytokines of peritoneal macrophages stimulated with LPS in vitro. Thus we concluded that myricetin could attenuate the LPS induced cardiac inflammation injury in vivo and in vitro. Myricetin may be a potential therapy or adjuvant therapy for SIMD.
Surface regulation is an effective strategy to improve the performance of catalysts, but it has been rarely demonstrated for nitrogen reduction reaction (NRR) to date. Now, surface‐rough Rh2Sb nanorod (RNR) and surface‐smooth Rh2Sb NR (SNR) were selectively created, and their performance for NRR was investigated. The high‐index‐facet bounded Rh2Sb RNRs/C exhibit a high NH3 yield rate of 228.85±12.96 μg h−1 mg−1Rh at −0.45 V versus reversible hydrogen electrode (RHE), outperforming the Rh2Sb SNRs/C (63.07±4.45 μg h−1 mg−1Rh) and Rh nanoparticles/C (22.82±1.49 μg h−1 mg−1Rh), owing to the enhanced adsorption and activation of N2 on high‐index facets. Rh2Sb RNRs/C also show durable stability with negligible activity decay after 10 h of successive electrolysis. The present work demonstrates that surface regulation plays an important role in promoting NRR activity and provides a new strategy for creating efficient NRR electrocatalysts.
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