RESUMEN
Nitrate is an important raw material for chemical fertilizers, but it is industrially manufactured in multiple steps at high temperature and pressure, urgently motivating the design of a green and sustainable strategy for nitrate production. We report the photosynthesis of nitrate from N2 and O2 on commercial TiO2 in a flow reactor under ambient conditions. The TiO2 photocatalyst offered a high nitrate yield of 1.85â µmol h-1 as well as a solar-to-nitrate energy conversion efficiency up to 0.13 %. We combined reactivity and in situ Fourier transform infrared spectroscopy to elucidate the mechanism of nitrate formation and unveil the special role of O2 in N≡N bond dissociation. The mechanistic insight into charge-involved N2 oxidation was further demonstrated by in situ transient absorption spectroscopy and electron paramagnetic resonance. This work exhibits the mechanistic origin of N2 photooxidation and initiates a potential method for triggering inert catalytic reactions.
RESUMEN
Li6-xZr2-xAxO7 (A = Nb; Ta) system with 0 < x < 0.30 is synthesized by glycine-nitrate method. Boundaries of solid solutions based on monoclinic Li6Zr2O7 are determined; temperature (200-600 °C) and concentration dependences of conductivity are investigated. It is shown that monoclinic Li6Zr2O7 exhibits better transport properties compared to its triclinic modification. Li5.8Zr1.8Nb(Ta)0.2O7 solid solutions have a higher lithium-cation conductivity at 300 °C compared to solid electrolytes based on other lithium zirconates due the "open" structure of monoclinic Li6Zr2O7 and a high solubility of the doping cations.
RESUMEN
NO is a harmful pollutant to the environment. The traditional removal of NO is hindered by the harsh operating conditions and sacrifice of value-added chemicals. Efficient electrocatalytic oxidation of NO was achieved over plasma-treated commercial carbon cloth, serving as a promising anode substitution reaction to couple with the hydrogen evolution reaction without consumption of hydrogen-containing resources. The introduction of carboxyl groups onto the carbon cloth boosted the electrocatalytic activity via the enhancement of NO chemisorption. Only potentials of 1.39â V and 1.07â V were applied to reach the current density of 10â mA cm-2 in neutral and acidic conditions, respectively, which is superior to the state-of-the-art electrocatalysts for oxygen evolution. Energy and environmental concerns on fossil-fuel-derived hydrogen production, ammonia manufacture and nitrate synthesis, are greatly alleviated. This work provides an original strategy to realize the resource utilization of NO, the sustainable nitrate synthesis and hydrogen production in a green and economical way.
RESUMEN
A facile pathway of the electrocatalytic nitrogen oxidation reaction (NOR) to nitrate is proposed, and Ru-doped TiO2 /RuO2 (abbreviated as Ru/TiO2 ) as a proof-of-concept catalyst is employed accordingly. Density functional theory (DFT) calculations suggest that Ruδ + can function as the main active center for the NOR process. Remarkably doping Ru into the TiO2 lattice can induce an upshift of the d-band center of the Ru site, resulting in enhanced activity for accelerating electrochemical conversion of inert N2 to active NO*. Overdoping of Ru ions will lead to the formation of additional RuO2 on the TiO2 surface, which provides oxygen evolution reaction (OER) active sites for promoting the redox transformation of the NO* intermediate to nitrate. However, too much RuO2 in the catalyst is detrimental to both the selectivity of the NOR and the Faradaic efficiency due to the dominant OER process. Experimentally, a considerable nitrate yield rate of 161.9 µmol h-1 gcat -1 (besides, a total nitrate yield of 47.9 µg during 50 h) and a highest nitrate Faradaic efficiency of 26.1% are achieved by the Ru/TiO2 catalyst (with the hybrid composition of Rux Tiy O2 and extra RuO2 by 2.79 wt% Ru addition amount) in 0.1 m Na2 SO4 electrolyte.