RESUMEN
Electrochemical reduction reaction of nitrate (NITRR) provides a sustainable route toward the green synthesis of ammonia. Nevertheless, it remains challenging to achieve high-performance electrocatalysts for NITRR especially at low overpotentials. In this work, hierarchical nanospheres consisting of polycrystalline Iridium&copper (Ir&Cu) and amorphous Cu2 O (Cux Iry Oz NS) have been fabricated. The optimal species Cu0.86 Ir0.14 Oz delivers excellent catalytic performance with a desirable NH3 yield rate (YR) up to 0.423 mmol h-1 cm-2 (or 4.8 mg h-1 mgcat -1 ) and a high NH3 Faradaic efficiency (FE) over 90% at a low overpotential of 0.69 V (or 0 VRHE ), where hydrogen evolution reaction (HER) is almost negligible. The electrolyzer toward NITRR and hydrazine oxidation (HzOR) is constructed for the first time with an electrode pair of Cu0.86 Ir0.14 Oz //Cu0.86 Ir0.14 Oz , yielding a high energy efficiency (EE) up to 87%. Density functional theory (DFT) calculations demonstrate that the dispersed Ir atom provides active site that not only promotes the NO3 - adsorption but also modulates the H adsorption/desorption to facilitate the proton supply for the hydrogenation of *N, hence boosting the NITRR. This work thus points to the importance of both morphological/structural and compositional engineering for achieving the highly efficient catalysts toward NITRR.
RESUMEN
An anionic layered coordination polymer [Eu(BTEC)0.5(HCOO)(H2O)2] (1) has been successfully synthesized via a solvothermal method (H4BTEC = 1,2,4,5-benzenetetracarboxylic acid, HCOOH = formic acid). Compound 1 possesses two-dimensional layers, which further generate a three-dimensional supramolecular network by hydrogen bonds existing between carboxylic oxygen, formate anion and H2O molecules of two adjacent layers. Interestingly, 1 shows high luminescence quenching efficiency upon addition of Fe3+ ions when it was dispersed in water even in the presence of interfering ions such as Na+, Ag+, Ca2+, Cd2+, Co2+, Cu2+, Mg2+, Mn2+, Zn2+ and Al3+. When dispersed in DMSO solution, 1 displays excellent sensitivity and selectivity towards both Cu2+ and Fe3+ ions. Possible quenching mechanisms for detection of Fe3+ and Cu2+ ions were carefully investigated and proposed based on a dynamic quenching process, static quenching process and fluorescence inner filter effect. Moreover, the as-prepared particles can be used for visualizing latent fingerprints on various substrates. These results indicate that a Eu(iii)-based coordination polymer has great potential in detection and security application.
