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Methanol oxidation reaction (MOR) efficiency is lowered by poor COads-tolerance and structural stability of Pt-based catalysts. Herein, single crystal Ni3S2 nanorods (with exposed {110} high-index ...

The synergies between transition metal oxides (bimetallic oxides) play important roles in determining the bifunctional catalytic activity for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline media. This study uses a facile hydrothermal method for uniformly coating CeO2 shells on the surfaces of ZIF-67-derived porous Co3O4@Z67-NT (T-temperature, 500–900 °C) cores. Co3O4@Z67-N700@CeO2 exhibits excellent bifunctional (ORR/OER) catalytic activity with a ΔE [Ej=10(OER) − E1/2(ORR)] of 0.70 V. For ORR, Co3O4@Z67-N700@CeO2 exhibits a higher half-wave potential of 0.88 V (vs. RHE) than that of commercial Pt/C (0.87 V), which is attributed to the synergies between CeO2 (Ce3+) and Co3O4 (Co2+). The oxygen vacancies on CeO2 can enhance O2 adsorption on the interfaces to promote the activation of adsorbed O2 to O2−, and can alleviate O2 deficiency during ORR, thereby improving ORR activity. For OER, Co3O4@Z67-N700@CeO2 has a lower overpotential of 350 mV at 10 mA cm−2 and a higher Faraday efficiency of 92.2% than those of RuO2. An effective valence transition between Ce3+ and Ce4+ endows CeO2 with high electrical conductivity and oxygen storage capacity, which greatly promote charge transfer and the generation/smooth transport of highly active species (O22−/O−). Moreover, the interactions between CeO2 (Ce3+/Ce4+ and oxygen vacancies) and Co3O4 (Co3+/CoOOH) provide more electrochemically active sites for OER. This study provides a new strategy for constructing the stable core@shell structure based on MOF derivatives to improve the ORR/OER performance.

RNA polymerase III (Pol III) products play essential roles in ribosome assembly, protein synthesis, and cell survival. Deregulation of Pol-III-directed transcription is closely associated with tumorigenesis. However, the regulatory pathways or factors controlling Pol-III-directed transcription remain to be investigated. In this study, we identified a novel role of EGR1 in Pol-III-directed transcription. We found that Filamin A (FLNA) silencing stimulated EGR1 expression at both RNA and protein levels. EGR1 expression positively correlated with Pol III product levels and cell proliferation activity. Mechanistically, EGR1 downregulation dampened the occupancies of Pol III transcription machinery factors at the loci of Pol III target genes. Alteration of EGR1 expression did not affect the expression of p53, c-MYC, and Pol III general transcription factors. Instead, EGR1 activated RhoA expression and inhibited PTEN expression in several transformed cell lines. We found that PTEN silencing, rather than RhoA overexpression, could reverse the inhibition of Pol-III-dependent transcription and cell proliferation caused by EGR1 downregulation. EGR1 could positively regulate AKT phosphorylation levels and is required for the inhibition of Pol-III-directed transcription mediated by FLNA. The findings from this study indicate that EGR1 can promote Pol-III-directed transcription and cell proliferation by controlling the PTEN/AKT signalling pathway.

The main issues regarding the practical application of microbial fuel cells (MFCs) are the poor activity and tolerance of oxygen reduction reaction (ORR) catalysts in wastewater. In this study, Auricularia chelated with Co, Fe and S ions is used as a nitrogen (N)-enriched carbon source to prepare N-doped bimetallic sulfide (Co

The sluggish kinetics of oxygen reduction reaction (ORR), especially in acid media, seriously restrains the commercialization of direct methanol fuel cells. Herein, we synthesize a hierarchical Co3O4@N-doped partly-graphitized carbon wrapped by Ti3+-self-doped TiO2 nanoparticles with multiple crystal-phases (anatase and rutile TiO2) as catalysts (Co3O4@NGC@MP-TiO2) for ORR in alkaline/acid media using ZIF-67 as a precursor. Co3O4@NGC@MP-TiO2-0.3 (tetrabutyl titanate of 0.3 mL) exhibits the same peak potential (Epeak of 0.83 V, vs. RHE) as Pt/C in 0.1 M KOH and the comparable Epeak (0.69 V) to Pt/C (0.7 V) in 0.5 M H2SO4. Synergistic effects between tetrahedral Co2+ (Co3O4) and Ti3+ (MP-TiO2) chiefly contribute to the high ORR activity. ORR stabilities of Co3O4@NGC@MP-TiO2-0.3 are higher than those of Pt/C in alkaline/acid media, attributing to that NGC@MP-TiO2 shell can protect active sites (tetrahedral Co2+ and N species) from corrosion and deactivation. Moreover, the dissociated adsorption of O2 on Ti3+ may facilitate the O2 protonation (Ti4+–OOHads−) to accelerate electron-transfer process and ORR kinetics in acid electrolyte, while acid-pickling of CoOx@NGC improves the stability of Co3O4@NGC to further smooth ORR process. This study provides a promising strategy for the design of highly-active and stable ORR catalysts in both alkaline and acid electrolytes.

Fabrication of efficient catalyst/co-catalyst for enhancing methanol oxidation and oxygen reduction reactions (MOR/ORR) is the key to make direct methanol fuel cells more economical. Here, hierarchical CoO@nitrogen-doped porous carbon@SnO2 (CoO@NPC@SnO2) polyhedrons are prepared as active catalysts for ORR and Pt supports/co-catalysts for MOR using zeolitic imidazolate frameworks-67 (ZIF-67). For ORR, CoO@NPC@SnO2-1 (Co@NPC-to-SnCl2·2H2O mass ratio of 1: 1) exhibits a more positive peak potential (0.82 V vs. RHE) than that of commercial Pt/C (10 wt.%). Outer SnO2 shells can prevent CoO cores (active tetrahedral Co2+) from corrosion during ORR. For MOR, Pt-CoO@NPC@SnO2-1 (5 wt.%) shows a much higher mass activity (1518 mA mgPt−1) than that of Pt/C (496.8 mA mgPt−1). High CO tolerance of Pt-CoO@NPC@SnO2-1 is attributed to strong metal (Pt)-metal oxides (SnO2) interactions, which facilitate adsorption of OH− on SnO2 to remove COads. Therefore, this study provides a strategy to enhance ORR/MOR performance by using hierarchically-structured catalysts/co-catalysts from ZIF templates.

Anodic electro-catalysis oxidation is a highly effective way to solve the pollution problem of antibiotics in wastewater and receiving water bodies. In this study, for the first time, molybdenum trioxide/Nano-graphite (MoO3/Nano-G) composites are synthesized as anodic catalysts by a surfactant-assisted solvothermal method followed by low-temperature calcination. The effects of the proportion of MoO3 to Nano-G (10, 30 and 50%) on the properties of composites are investigated through structural characterizations and electrochemical measurements. Results indicate that MoO3(30)/Nano-G electrode displays the electro-catalysis degradation efficiency of 99.9% towards ceftazidime, which is much higher than those of Nano-G (46.7%) and dimensionally stable anode (69.2%). The degradation mechanism for ceftazidime is studied by investigating the yields and kinds of active species. Results show that all of the OH, O2- and H2O2 are responsible for the electro-catalytic degradation process, and the produced OH radicals are the major active species for ceftazidime degradation. The synergistic effects between MoO3 and Nano-G greatly contribute to the activation of H2O molecules to produce OH, meanwhile the special sesame cake-like structure facilitates to the exposure of contaminants to OH on active sites to enhance the degradation efficiency. These results suggest that MoO3/Nano-G electrodes can be considered as the promising catalysts for treating bio-refractory organic wastewater.