Crystalline FeVO 4 nanopolyhedron (FVO NPH) photoelectrodes are successfully prepared by using an in situ solid-state transformation from hydrothermal FeOOH films via adding vanadium precursor and following thermal treatments. The FVO NPH photoelectrodes possess uniformly dispersed polyhedral nanocrystals that directly grow on the conductive substrate with tunable film thicknesses. The unique morphology enables an outstanding photo-electrocatalytic performance, and the optimized FVO NPH photoelectrode, which was annealed at 550°C for 4 h with a film thickness of~560 nm, exhibits excellent photocurrent densities of~0.47 and~0.68 mA cm À 2 at 1.0 and 1.2 V vs. Ag/AgCl, respectively. After decorating CoPi co-catalyst, FVO/CoPi shows a highly efficient water splitting performance with O 2 and H 2 evolution rates of 7.53 and 15.32 μmol cm À 2 h À 1 , respectively, which are~1.88 and~1.80 times, respectively, of these of the FVO NPH. The proposed photoelectrodes also show excellently chemical and physical stabilities in solar water splitting. This is the first time reported the preparation of wellorganized nanostructured FeVO 4 films, which warrants further optimization studies on morphologies and compositions of FeVO 4 -based photoelectrodes.
To quickly and quantitatively detect the concentration of harmful Cr 6+ in food and packaging, biomass nitrogen-doped blue fluorescent carbon quantum dots (CQDs) were synthesized by a one-step hydrothermal method using longan peel. The synthesized biomass CQDs are spherical, and the particle size is distributed between 1 and 6 nm. There are functional groups such as carboxyl, hydroxyl and amino groups on the surface of the CQDs, which promotes the excellent water dispersibility of the CQDs. CQDs have good fluorescence stability in salt solutions, different pH environments and long-term storage. A fluorescence sensor for detecting Cr 6+ was constructed, based on the specific quenching effect of Cr 6+ on the fluorescence of CQDs. There is a good linear relationship between the fluorescence quenching rate of the fluorescence sensor and the Cr 6+ concentration of the detected sample. The sensor has a linear range of 20-200 μM and a detection limit of 1.4 μM. In addition, the CQDs fluorescence sensor has an ideal recovery rate in the actual water sample spiked with Cr 6+ . This research innovatively combined longan and hydrothermal method to prepare a quantitative, fast and wide detection limit Cr 6+ sensor.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.