Lithium-mediated electrochemical nitrogen reduction: Mechanistic insights to enhance performance

Green synthesis of ammonia by electrochemical nitrogen reduction reaction (NRR) shows great potential as an alternative to the Haber-Bosch process but is hampered by sluggish production rate and low Faradaic efficiency. Recently, lithium-mediated electrochemical NRR has received renewed attention due to its reproducibility. However, further improvement of the system is restricted by limited recognition of its mechanism. Herein, we demonstrate that lithium-mediated NRR began with electrochemical deposition of lithium, followed by two chemical processes of dinitrogen splitting and protonation to ammonia. Furthermore, we quantified the extent to which the freshly deposited active lithium lost its activity toward NRR due to a parasitic reaction between lithium and electrolyte. A high ammonia yield of 0.410 ± 0.038 μg s-1 cm-2 geo and Faradaic efficiency of 39.5 ± 1.7% were achieved at 20 mA cm-2 geo and 10 mA cm-2 geo, respectively, which can be attributed to fresher lithium obtained at high current density

Composition-Graded Pd_<i>x</i>Ni_1–<i>x</i> Nanospheres with Pt Monolayer Shells as High-Performance Electrocatalysts for Oxygen Reduction Reaction

It is undoubtedly desirable, albeit very challenging, to appropriately balance the catalytic activity, electrochemical durability, and noble-metal (NM) utilization when developing Pt-based catalysts for oxygen reduction reaction (ORR). Accordingly, in this work, a versatile and effective strategy that promises the nanostructure of both composition-graded core and mono- or multilayer shell is proposed to synthesize highly uniform, sub-10 nm Pd_<i>x</i>Ni_1–<i>x</i>@Pt nanospheres (NSs) as high-performance ORR electrocatalysts. Highly uniform and composition-graded Pd_<i>x</i>Ni_1–<i>x</i> NSs are previously obtained via a facile one-pot Ni-substitution-based process, and then Pt mono- or multilayer shells are coated onto them through Cu underpotential deposition coupled with Pt²⁺ galvanic displacement. Results show that carbon-supported Pd_<i>x</i>Ni_1–<i>x</i>@Pt electrocatalysts possess both high catalytic activity and highly efficient NM utilization toward ORR. The optimized Pd_0.42Ni_0.58@Pt/C exhibits 0.61 mA cm^–2, 0.42 A mg^–1_Pd+Pt, and 1.45 A mg^–1_Pt @ 0.9 V (vs RHE) in the area-specific, NM-mass-specific, and Pt-mass-specific activity, respectively, reaching 2.8, 3.3, and 11.2 times relative to those of the commercial Pt/C. Moreover, Pd_0.42Ni_0.58@Pt/C also has a satisfactory electrochemical durability, preserving its high ORR catalytic activity even after 12 000 potential cycles of the accelerated degradation test. The synthetic mechanism of Pd_<i>x</i>Ni_1–<i>x</i> NS core, Pt monolayer shell and their combined effects on the catalytic activity, electrochemical durability, and NM utilization of Pd_<i>x</i>Ni_1–<i>x</i>@Pt/C toward ORR are comprehensively investigated

Lactobacillus gasseri LGV03 isolated from the cervico-vagina of HPV-cleared women modulates epithelial innate immune responses and suppresses the growth of HPV-positive human cervical cancer cells

Persistent human papillomavirus (HPV) infections is necessary for the development of cervical cancers. An increasing number of retrospective studies have found the depletion of Lactobacillus microbiota in the cervico-vagina facilitate HPV infection and might be involved in viral persistence and cancer development. However, there have been no reports confirming the immunomodulatory effects of Lactobacillus microbiota isolated from cervico-vaginal samples of HPV clearance in women. Using cervico-vaginal samples from HPV persistent infection and clearance in women, this study investigated the local immune properties in cervical mucosa. As expected, type I interferons, such as IFN-α and IFN-β, and TLR3 globally downregulated in HPV+ persistence group. Luminex cytokine/chemokine panel analysis revealed that L. jannaschii LJV03, L. vaginalis LVV03, L. reuteri LRV03, and L. gasseri LGV03 isolated from cervicovaginal samples of HPV clearance in women altered the host's epithelial immune response, particularly L. gasseri LGV03. Furthermore, L. gasseri LGV03 enhanced the poly (I:C)-induced production of IFN by modulating the IRF3 pathway and attenuating poly (I:C)-induced production of proinflammatory mediators by regulating the NF-κB pathway in Ect1/E6E7 cells, indicating that L. gasseri LGV03 keeps the innate system alert to potential pathogens and reduces the inflammatory effects during persistent pathogen infection. L. gasseri LGV03 also markedly inhibited the proliferation of Ect1/E6E7 cells in a zebrafish xenograft model, which may be attributed to an increased immune response mediated by L. gasseri LGV03