Synergistic Al-Al Dual-Atomic Site for Efficient Artificial Nitrogen Fixation.

Synthesis of ammonia by electrochemical nitrogen reduction reaction (NRR) is a promising alternative to the Haber-Bosch process. However, it is commonly obstructed by the high activation energy. Here, we report the design and synthesis of an Al-Al bonded dual atomic catalyst stabilized within an amorphous nitrogen-doped porous carbon matrix (Al2NC) with high NRR performance. The dual atomic Al2-sites act synergistically to catalyze the complex multiple steps of NRR through adsorption and activation, enhancing the proton-coupled electron transfer. This Al2NC catalyst exhibits a high Faradaic efficiency of 16.56±0.3 % with a yield rate of 29.22±1.2 µg h-1 mgcat -1. The dual atomic Al2NC catalyst shows long-term repeatable, and stable NRR performance. This work presents an insight into the identification of synergistic dual atomic catalytic site and mechanistic pathway for the electrochemical conversion of N2 to NH3.

One-pot solvothermal synthesis of reduced graphene oxide-supported uniform PtCo nanocrystals for efficient and robust electrocatalysis.

Pt-based nanocomposites with low Pt utilization and high-activity by incorporating with other transition metals have received significant interest in catalysis. Meanwhile, loading Pt-based catalysts on graphene has great research value for improved stability and dispersity of the catalysts. Herein, a facile l-proline-mediated solvothermal strategy was reported to construct reduced graphene oxide (rGO) supported sheet-like PtCo nanocrystals (Pt78Co22 NCs/rGO) in ethylene glycol (EG). The as-synthesized nanocomposite manifested remarkably improved catalytic properties and chemical stability for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), surpassing home-made Pt29Co71 nanoparticles (NPs)/rGO, Pt83Co17 NPs/rGO, Pt52Co48 NPs, commercial Pt/C and Pt black catalysts. These scenarios demonstrated an improved catalytic performances by tailoring the feeding ratio of Pt:Co and introducing rGO as a support. This work provides some new insights to design rGO-supported Pt-based catalysts by engineering the shapes and compositions in practical fuel cells.

HIF-1α protects against oxidative stress by directly targeting mitochondria.

The transcription factor hypoxia inducible factor-1α (HIF-1α) mediates adaptive responses to oxidative stress by nuclear translocation and regulation of gene expression. Mitochondrial changes are critical for the adaptive response to oxidative stress. However, the transcriptional and non-transcriptional mechanisms by which HIF-1α regulates mitochondria in response to oxidative stress are poorly understood. Here, we examined the subcellular localization of HIF-1α in human cells and identified a small fraction of HIF-1α that translocated to the mitochondria after exposure to hypoxia or H2O2 treatment. Moreover, the livers of mice with CCl4-induced fibrosis showed a progressive increase in HIF-1α association with the mitochondria, indicating the clinical relevance of this finding. To probe the function of this HIF-1α population, we ectopically expressed a mitochondrial-targeted form of HIF-1α (mito-HIF-1α). Expression of mito-HIF-1α was sufficient to attenuate apoptosis induced by exposure to hypoxia or H2O2-induced oxidative stress. Moreover, mito-HIF-1α expression reduced the production of reactive oxygen species, the collapse of mitochondrial membrane potential, and the expression of mitochondrial DNA-encoded mRNA in response to hypoxia or H2O2 treatment independently of nuclear pathways. These data suggested that mitochondrial HIF-1α protects against oxidative stress induced-apoptosis independently of its well-known role as a transcription factor.

Uric acid supported one-pot solvothermal fabrication of rhombic-like Pt35Cu65 hollow nanocages for highly efficient and stable electrocatalysis.

High activity and good durability of electrocatalysts are of significance in practical applications of fuel cells. Among them, multi-component metallic hollow nanocages/nanoframes show great potential as advanced catalysts because of their highly open structures, large surface area and good stability. Herein, we report a general uric acid-mediated solvothermal method for shape-controlled synthesis of rhombic-like Pt35Cu65 hollow nanocages (HNCs) with uric acid as co-reductant and co-structure-directing agent. Uric acid and cetyltrimethylammonium chloride (CTAC) played important roles in the hollow cages. The specific architectures showed remarkably enhanced catalytic properties towards glycerol oxidation reaction (GOR), ethylene glycol oxidation reaction (EGOR) and oxygen reduction reaction (ORR) with the enhanced specific activity, outperforming commercial Pt/C (20 wt%). This work provides a new avenue for rational design of novel bimetallic nanocatalysts with enhanced characters in energy storage and conversion.

Facile solvothermal synthesis of Pt71Co29 lamellar nanoflowers as an efficient catalyst for oxygen reduction and methanol oxidation reactions.

The research for highly efficient and stable electrocatalysts in fuel cells has attracted substantial interest. Herein, bimetallic alloyed Pt71Co29 lamellar nanoflowers (LNFs) with abundant active sites were obtained by a one-pot solvothermal method, where cetyltrimethylammonium chloride (CTAC) and 1-nitroso-2-naphthol (1-N-2-N) served as co-structure-directors, while oleylamine (OAm) as the solvent and reducing agent. The fabricated Pt71Co29 LNFs exhibited the higher mass activity (MA, 128.29 mA mg-1) for oxygen reduction reaction (ORR) than those of home-made Pt48Co52 nanodendrites (NDs), Pt79Co21 NDs and commercial Pt black with the values of 39.46, 49.42 and 22.91 mA mg-1, respectively. Meanwhile, the MA (666.23 mA mg-1) and specific activity (SA, 2.51 mA cm-2) of the constructed Pt71Co29 LNFs for methanol oxidation reaction (MOR) are superior than those of Pt48Co52 NDs (213.91 mA mg-1, 1.99 mA cm-2), Pt79Co21 NDs (210.09 mA mg-1, 1.12 mA cm-2) and Pt black (57.03 mA mg-1, 0.25 mA cm-2). Also, the Pt71Co29 LNFs catalyst exhibited the best durable ability relative to the references. This work demonstrates that the developed strategy provides a facile platform for synthesis of high-performance, low-cost and robust catalysts in practical catalysis, energy storage and conversion.

Facile solvothermal fabrication of polypyrrole sheets supported dendritic platinum-cobalt nanoclusters for highly efficient oxygen reduction and ethylene glycol oxidation.

Herein, uniform dendritic PtCo nanoclusters supported on sheet-like polypyrrole (PtCo NCs/PPy) were prepared by a facile one-pot solvothermal method. Cetyltrimethylammonium chloride (CTAC) and pyrrole worked as the capping agent and reductant, respectively, and pyrrole was in-situ polymerized to form PPy sheets under solvothermal conditions. The dendritic PtCo NCs/PPy had the enlarged electrochemically active surface area (EASA, 30.95 m2g-1), and showed the superior catalytic performance and durability towards oxygen reduction reaction (ORR) and ethylene glycol oxidation reaction (EGOR) in comparison with Pt1Co3 nanoparticles (NPs), Pt3Co1 NPs and commercial Pt/C catalysts. This work displays a new strategy for rational design and synthesis of advanced functional nanocomposites as electrocatalysts in fuel cells.

Facile solvothermal fabrication of Pt47Ni53 nanopolyhedrons for greatly boosting electrocatalytic performances for oxygen reduction and hydrogen evolution.

Pt-based bimetallic nanostructures with low content of Pt were considered as one of the attractive nanocatalysts for their high Pt utilization efficiency, remarkable catalytic characters and cost-effectiveness in facilitating the sluggish cathodic reactions in fuel cells. Herein, three-dimensional Pt47Ni53 nanopolyhedrons (NPHs) with abundant active sites were constructed by a facile one-pot solvothermal strategy, in which cytosine and cetyltrimethylammonium chloride (CTAC) worked as the co-structure directing agents. The Pt47Ni53 NPHs were mainly characterized by a series of techniques, showing the high catalytic activity and stability towards oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) in comparison to Pt13Ni87 nanocrystals (NCs), Pt63Ni37 NCs, commercial Pt black and/or Pt/C catalysts. Impressively, the mass activity of Pt47Ni53 NPHs was about 215.80 mA mgPt-1 for ORR, approximately 4-time increase relative to Pt black (49.60 mA mgPt-1). These results demonstrate the promising applications of the synthesized nanocatalysts in energy storage and transformation.

One-pot fabrication of reduced graphene oxide supported dendritic core-shell gold@gold-palladium nanoflowers for glycerol oxidation.

Herein, a one-pot wet-chemical route was used to prepare well-defined dendritic core-shell gold@gold-palladium nanoflowers supported on reduced graphene oxide (Au@AuPd NFs/rGO), using 2, 4-dihydroxypyridine (2, 4-DHP) asa new stabilizer and structure-director. Their morphology, size, composition, and crystal structure were characterized by a set of characterization techniques. Control experiments demonstrated that the molar ratio of the metal precursors and the dosage of 2,4-DHP play essential roles in this synthesis. The growth mechanism of dendritic core-shell Au@AuPd nanoflowers was investigated in details. The synthesized branched architectures exhibited enlarged electrochemically active surface area (ECSA), improved catalytic properties, enhanced stability and durability toward glycerol oxidation in alkaline media when compared to the home-made Au26Pd74 nanocrystals (NCs)/rGO and Au78Pd22 NCs/rGO, along with commercially available Pd/C catalyst.