A fundamental understanding of the origin of oxygen evolution reaction (OER) activity of transition-metal-based electrocatalysts, especially for single precious metal atoms supported on layered double hydroxides (LDHs), is highly required for the design of efficient electrocatalysts toward further energy conversion technologies. Here, we aim toward single-atom Au supported on NiFe LDH (Au/NiFe LDH) to clarify the activity origin of LDHs system and a 6-fold OER activity enhancement by 0.4 wt % Au decoration. Combining with theoretical calculations, the active behavior of NiFe LDH results from the in situ generated NiFe oxyhydroxide from LDH during the OER process. With the presence ofAu, Au/NiFe LDH possesses an overpotential of 0.21 V in contrast to the calculated result (0.18 V). We ascribe the excellent OER activity ofAu/NiFe LDH to the charge redistribution of active Fe as well as its surrounding atoms causing by the neighboring Au on NiFe oxyhydroxide stabilized by interfacial CO and HO interfacing with LDH.
For many regenerative electrochemical energy-conversion systems, hybrid electrocatalysts comprising transition metal (TM) oxides and heteroatom-doped (e.g., nitrogen-doped) carbonaceous materials are promising bifunctional oxygen reduction reaction/oxygen evolution reaction electrocatalysts, whose enhanced electrocatalytic activities are attributed to the synergistic effect originated from the TM-N-C active sites. However, it is still ambiguous which configuration of nitrogen dopants, either pyridinic or pyrrolic N, when bonded to the TM in oxides, predominately contributes to the synergistic effect. Herein, an innovative strategy based on laser irradiation is described to controllably tune the relative concentrations of pyridinic and pyrrolic nitrogen dopants in the hybrid catalyst, i.e., NiCo O NPs/N-doped mesoporous graphene. Comparative studies reveal the dominant role of pyridinic-NCo bonding, instead of pyrrolic-N bonding, in synergistically promoting reversible oxygen electrocatalysis. Moreover, density functional theory calculations provide deep insights into the corresponding synergistic mechanism. The optimized hybrid, NiCo/NLG-270, manifests outstanding reversible oxygen electrocatalytic activities, leading to an overpotential different ΔE among the lowest value for highly efficient bifunctional catalysts. In a practical reversible Zn-air battery, NiCo/NLG-270 exhibits superior charge/discharge performance and long-term durability compared to the noble metal electrocatalysts.
The legume-rhizobium symbiosis results in nitrogen-fixing root nodules, and their formation involves both intracellular infection initiated in the epidermis and nodule organogenesis initiated in inner root cell layers. NODULE INCEPTION (NIN) is a nodule-specific transcription factor essential for both processes. These NIN-regulated processes occur at different times and locations in the root, demonstrating a complex pattern of spatiotemporal regulation. We show that regulatory sequences sufficient for the epidermal infection process are located within a 5 kb region directly upstream of the NIN start codon in Medicago truncatula. Furthermore, we identify a remote upstream cis-regulatory region required for the expression of NIN in the pericycle, and we show that this region is essential for nodule organogenesis. This region contains putative cytokinin response elements and is conserved in eight more legume species. Both the cytokinin receptor 1, which is essential for nodule primordium formation, and the B-type response regulator RR1 are expressed in the pericycle in the susceptible zone of the uninoculated root. This, together with the identification of the cytokinin-responsive elements in the NIN promoter, strongly suggests that NIN expression is initially triggered by cytokinin signaling in the pericycle to initiate nodule primordium formation.
Water splitting is promising to realize a hydrogen‐based society. The practical use of molecular water‐splitting catalysts relies on their integration onto electrode materials. We describe herein the immobilization of cobalt corroles on carbon nanotubes (CNTs) by four strategies and compare the performance of the resulting hybrids for H2 and O2 evolution. Co corroles can be covalently attached to CNTs with short conjugated linkers (the hybrid is denoted as H1) or with long alkane chains (H2), or can be grafted to CNTs via strong π–π interactions (H3) or via simple adsorption (H4). An activity trend H1≫H3>H2≈H4 is obtained for H2 and O2 evolution, showing the critical role of electron transfer ability on electrocatalysis. Notably, H1 is the first Janus catalyst for both H2 and O2 evolution reactions in pH 0–14 aqueous solutions. Therefore, this work is significant to show potential uses of electrode materials with well‐designed molecular catalysts in electrocatalysis.
The transient receptor potential canonical subfamily member 5 (TRPC5), one of seven mammalian TRPC members, is a nonselective calcium-permeant cation channel. TRPC5 is of considerable interest as a drug target in the treatment of progressive kidney disease, depression, and anxiety. Here, we present the 2.8-Å resolution cryo–electron microscopy (cryo-EM) structure of the mouse TRPC5 (mTRPC5) homotetramer. Comparison of the TRPC5 structure to previously determined structures of other TRPC and TRP channels reveals differences in the extracellular pore domain and in the length of the S3 helix. The disulfide bond at the extracellular side of the pore and a preceding small loop are essential elements for its proper function. This high-resolution structure of mTRPC5, combined with electrophysiology and mutagenesis, provides insight into the lipid modulation and gating mechanisms of the TRPC family of ion channels.
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