It’s highly desired but challenging to synthesize self-supporting nanohybrid made of conductive nanoparticles with metal organic framework (MOF) materials for the application in the electrochemical field. In this work, we report the preparation of Ni2P embedded Ni-MOF nanosheets supported on nickel foam through partial phosphidation (Ni2P@Ni-MOF/NF). The self-supporting Ni2P@Ni-MOF/NF was directly tested as electrode for urea electrolysis. When served as anode for urea oxidation reaction (UOR), it only demands 1.41 V (vs RHE) to deliver a current of 100 mA cm−2. And the overpotential of Ni2P@Ni-MOF/NF to reach 10 mA cm−2 for hydrogen evolution reaction HER was only 66 mV, remarkably lower than Ni2P/NF (133 mV). The exceptional electrochemical performance was attributed to the unique structure of Ni2P@Ni-MOF and the well exposed surface of Ni2P. Furthermore, the Ni2P@Ni-MOF/NF demonstrated outstanding longevity for both HER and UOR. The electrolyzer constructed with Ni2P@Ni-MOF/NF as bifunctional electrode can attain a current density of 100 mA cm−2 at a cell voltage as low as 1.65 V. Our work provides new insights for prepare MOF based nanohydrid for electrochemical application.
The application of microscale zerovalent iron (mZVI) in the removal of Cr(VI) from water is plagued with the readily formation of oxide passivation layer. In this study, we propose a “capture-reduction” mechanism to enhance the Cr(VI) removal performance of mZVI under anaerobic condition through dual modification, i.e., sulfidation and construction of composite with sulfur-doped graphene like biochar (SGB). The S-mZVI/SGB has a Cr(VI) removal capacity of 70.2 mg·g− 1 at circumneutral pH, which is 56 times of that of mZVI. The 1,10-phenanthroline shielding experiments indicate that the contribution of Fe(II) to Cr(VI) removal is only 17.6%. Density-theory-functional (DFT) calculation results indicate that sulfur doping could significantly promote the adsorption of Cr(VI) on SGB nanosheets. The mechanism study confirmed the “capture-reduction” Cr(VI) removal mechanism, whereby the SGB nanosheets capture Cr(VI) ions and receive electrons from Fe0 to reduce Cr(VI) to Cr(III). Considering its advantages such as low cost and easy preparation, the S-mZVI/SGB composite is a promising green material for the removal of Cr(VI) from water.
Graphical Abstract
Cellular lipid storage is regulated by the balance of lipogenesis and lipolysis. The rate-limiting triglyceride hydrolase ATGL (desnutrin/PNPLA2) is critical for lipolysis. The control of ATGL transcription, localization and activation has been intensively studied, while regulation of the protein stability of ATGL is much less explored. Here we showed that the protein stability of ATGL is regulated by the N-end rule in cultured cells and in mice. The N-end rule E3 ligases UBR1 and UBR2 reduce the level of ATGL and affect lipid storage. The N-end rule-resistant ATGL(F2A) mutant, in which the N-terminal phenylalanine (F) of ATGL is substituted by alanine (A), has increased protein stability and enhanced lipolysis activity. ATGLF2A/F2A knock-in mice are protected against high-fat diet (HFD)-induced obesity, hepatic steatosis and insulin resistance. Hepatic knockdown of Ubr1 attenuates HFD-induced hepatic steatosis by enhancing the ATGL level. Finally, the protein levels of UBR1 and ATGL are negatively correlated in the adipose tissue of obese mice. Our study reveals N-end rule-mediated proteasomal regulation of ATGL, a finding which may potentially be beneficial for treatment of obesity.
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