ABSTRACT
Performance of single-atom catalysis largely depends on the interaction between the metal and the supporter. Herein, ethylene glycol (EG) was used as a molecular bridge connecting Palladium (Pd) and bismuth oxybromide (BiOBr) to form atomically dispersed Pd catalyst (Pd-EG-BiOBr) for photocatalytic nitrogen fixation under ambient conditions. Compared with 0.20 wt% Pd-BiOBr, 0.20 wt% Pd-EG-BiOBr greatly promoted the photocatalytic nitrogen fixation activity, affording an ammonia formation rate of 124.63 µmol·h-1. The molecular bridge mechanism during catalyst formation and photocatalysis is speculated based on Transmission electron microscopy, In-situ Fourier transform infrared spectra, Electron spin resonance spectra, UV-vis diffuse reflectance spectra, Photoluminescence spectra and Density Functional Theory calculations. The results show that EG not only induces the formation of atomically dispersed Pd, but also enhances the electron density of Pd and activation capacity of nitrogen molecules. This work opens a new door to applications of atomically dispersed Pd supported catalysts for high efficiency photocatalytic nitrogen fixation.
ABSTRACT
Photocatalytic nitrogen fixation has been considered to be a safe, green, eco-friendly, and sustainable technology. However, photoinduced activation of inert dinitrogen is an important factor hindering the development of this technology. Herein, in-situ Fe3+ doped flower-like BiOCl with highly active sites exposure was prepared by a solvent thermal method, which has excellent performance of N2 photofixation. Compared with virgin BiOCl with no nitrogen fixation activity, Fe-BiOCl reached 30 µmol·L-1·h-1 ammonia evolution rate under simulated sunlight without any sacrificial reagent. Characterization results demonstrated that the enhancement of N2 photofixation capacity was mainly attributed to the in-situ doped Fe3+ in BiOCl, the doped Fe3+ not only acts as a reaction center for N2 activation also as an "electron transfer bridge" trapping and migrating electrons from BiOCl to N2 molecules. Furthermore, the transformation of crystal facets from virgin BiOCl (001) to Fe-BiOCl (110) and (102) is more conducive for the exposure and accessibility of iron reactive sites. This work developed a potential strategy by in-situ introducing Fe3+ active sites in BiOCl semiconductor substrate, which establishes a good basis for the application of semiconductor catalysts in nitrogen fixation.
ABSTRACT
We show here that silver nanoparticles (AgNP) were intrinsically antibacterial, whereas gold nanoparticles (AuNP) were antimicrobial only when ampicillin was bound to their surfaces. Both AuNP and AgNP functionalized with ampicillin were effective broad-spectrum bactericides against Gram-negative and Gram-positive bacteria. Most importantly, when AuNP and AgNP were functionalized with ampicillin they became potent bactericidal agents with unique properties that subverted antibiotic resistance mechanisms of multiple-drug-resistant bacteria.
