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1.
J Am Chem Soc ; 141(38): 14976-14980, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31523954

RESUMO

The traditional NH3 production method (Haber-Bosch process) is currently complemented by electrochemical synthesis at ambient conditions, but the rather low selectivity (as indicated by the Faradaic efficiency) for the electrochemical reduction of molecular N2 into NH3 impedes the progress. Here, we present a powerful method to significantly boost the Faradaic efficiency of Au electrocatalysts to 67.8% for the nitrogen reduction reaction (NRR) by increasing their electron density through the construction of inorganic donor-acceptor couples of Ni and Au nanoparticles. The unique role of the electron-rich Au centers in facilitating the fixation and activation of N2 was also investigated via theoretical simulation methods and then confirmed by experimental results. The highly coupled Au and Ni nanoparticles supported on nitrogen-doped carbon are stable for reuse and long-term performance of the NRR, making the electrochemical process more sustainable for practical application.

2.
Nat Commun ; 10(1): 4380, 2019 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-31558716

RESUMO

Production of ammonia is currently realized by the Haber-Bosch process, while electrochemical N2 fixation under ambient conditions is recognized as a promising green substitution in the near future. A lack of efficient electrocatalysts remains the primary hurdle for the initiation of potential electrocatalytic synthesis of ammonia. For cheaper metals, such as copper, limited progress has been made to date. In this work, we boost the N2 reduction reaction catalytic activity of Cu nanoparticles, which originally exhibited negligible N2 reduction reaction activity, via a local electron depletion effect. The electron-deficient Cu nanoparticles are brought in a Schottky rectifying contact with a polyimide support which retards the hydrogen evolution reaction process in basic electrolytes and facilitates the electrochemical N2 reduction reaction process under ambient aqueous conditions. This strategy of inducing electron deficiency provides new insight into the rational design of inexpensive N2 reduction reaction catalysts with high selectivity and activity.

3.
Chem Commun (Camb) ; 55(76): 11394-11397, 2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-31482882

RESUMO

A nitrogen-thermal approach via the reaction between transition metal species and N dopants affords us the ability to optimize the tradeoff between the number of exposed transition metal/carbon (exemplified by cobalt in this work) boundaries and the most pronounced interfacial rectifying contact to achieve the highly efficient and selective hydrogenation and dehydrogenation of N-heterocycle compounds in a reversible manner.

4.
Chem Commun (Camb) ; 55(27): 3971-3974, 2019 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-30874700

RESUMO

We described an effective way to generate a Co3O4 mesocrystal array with well-developed porosity, simply by uniting a coupled interface with hydrazine treatment. Due to the fast electron transfer and sufficient active sites, the Ti mesh-supported Co3O4 nanoneedles electrode could provide a current density of 49.9 mA cm-2 at 570 mV OER overpotential and has exceptionally high stability.

5.
Angew Chem Int Ed Engl ; 57(38): 12563-12566, 2018 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-30070752

RESUMO

The exploitation of metal-free organic polymers as electrodes for water splitting reactions is limited by their presumably low activity and poor stability, especially for the oxygen evolution reaction (OER) under more critical conditions. Now, the thickness of a cheap and robust polymer, poly(p-phenylene pyromellitimide) (PPPI) was rationally engineered by an in situ polymerization method to make the metal-free polymer available for the first time as flexible, tailorable, efficient, and ultra-stable electrodes for water oxidation over a wide pH range. The PPPI electrode with an optimized thickness of about 200 nm provided a current density of 32.8 mA cm-2 at an overpotential of 510 mV in 0.1 mol L-1 KOH, which is even higher than that (31.5 mA cm-2 ) of commercial IrO2 OER catalyst. The PPPI electrodes are scalable and stable, maintaining 92 % of its activity after a 48-h chronoamperometric stability test.

6.
ChemSusChem ; 11(14): 2306-2309, 2018 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-29851293

RESUMO

Electrochemical gas evolution and activation reactions are complicated processes, involving not only active electrocatalysts but also the interaction among solid electrodes, electrolyte, and gas-phase products and reactants. In this study, multiphase interfaces of superadsorbing graphene-based electrodes were controlled without changing the active centers to significantly facilitate mass diffusion kinetics for superior performance. The achieved in-depth understanding of how to regulate the interfacial properties to promote the electrochemical performance could provide valuable clues for electrode manufacture and for the design of more active electrocatalysts.

7.
J Ethnopharmacol ; 204: 132-141, 2017 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-28412217

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: The heart wood of Dalbergia odorifera is a Chinese herbal medicine commonly used for the treatment of various ischemic diseases in Chinese medicine practice. AIM OF THE STUDY: In this study, therapeutic angiogenesis effects of the Dalbergia odorifera extract (DOE) were investigated on transgenic zebrafish in vivo and human umbilical vein endothelial cells (HUVECs) in vitro. MATERIALS AND METHODS: The pro-angiogenic effects of DOE on zebrafish were examined by subintestinal vessels (SIVs) sprouting assay and intersegmental vessels (ISVs) injury assay. And the pro-angiogenic effects of DOE on HUVECs were examined by MTT, scratch assay, protein chip and western blot. RESULTS: In the in vivo studies, we found that DOE was able to dose-dependently promote angiogenesis in zebrafish SIVs area. In addition, DOE could also restore the injury in zebrafish ISVs area and upregulate the reduced mRNA expression of VEGFRs including kdr, kdrl and flt-1 induced by VEGF receptor kinase inhibitor II (VRI). In the in vitro studies, we observed that DOE promoted the proliferation, migration of HUVECs and also restored the injury induced by VRI. Moreover, protein chip and western blot experiments showed the PI3K/MAPK cell proliferation/migration pathway were activated by DOE. CONCLUSIONS: DOE has a therapeutic effects on angiogenesis, and its mechanism may be related to adjusting the VEGFRs mRNA and activation of PI3K/MAPK signaling pathway. These results suggest a strong potential for Dalbergia odorifera to be developed as an angiogenesis-promoting therapeutic.


Assuntos
Indutores da Angiogênese/farmacologia , Dalbergia , Extratos Vegetais/farmacologia , Animais , Animais Geneticamente Modificados , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/fisiologia , Humanos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neovascularização Fisiológica/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Receptores de Fatores de Crescimento do Endotélio Vascular/metabolismo , Transdução de Sinais/efeitos dos fármacos , Peixe-Zebra/fisiologia
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