Biomimetic Mineralization Synthesis of Flower-Like Cobalt Selenide/Reduced Graphene Oxide for Improved Electrochemical Deionization.

Rationally and precisely tuning the composition and structure of materials is a viable strategy to improve electrochemical deionization (EDI) performances, which yet faces enormous challenges. Herein, an eco-friendly biomimetic mineralization synthetic strategy is developed to synthesize the flower-like cobalt selenide/reduced graphene oxide (Bio-CoSe2 /rGO) composites and used as advanced sodium ion adsorption electrodes. Benefiting from the slow and controllable reaction kinetics provided by the biomimetic mineralization process, the flower-like CoSe2 is uniformly constructed in the rGO, which is endowed with robust architecture, substantial adsorption sites and rapid charge/ion transport. The Bio-CoSe2 /rGO electrode yields the maximum salt adsorption capacity and salt adsorption rate of 56.3 mg g-1 and 5.6 mg g-1 min-1 respectively, and 92.5% capacity retention after 60 cycles. These results overmatch the pristine CoSe2 and irregular granular CoSe2 /rGO synthesized by a hydrothermal method, proving the structural superiority of the Bio-CoSe2 /rGO composites. Furthermore, the in-depth adsorption kinetics study indicates the chemisorption nature of sodium ion adsorption. The structures of the Bio-CoSe2 /rGO composites after long term EDI cycles are intensively studied to unveil the mechanism behind such superior EDI performances. This study offers one effective method for constructing advanced EDI electrodes, and enriches the application of the biomimetic mineralization synthetic strategy.

High mass loading and additive-free prussian blue analogue based flexible electrodes for Na-ion supercapacitors.

Supercapacitor electrodes often suffer from the low mass loading of active substances and the unsatisfactory ion/charge transport features due to the use of various additives. Exploring high mass loading and additive-free electrodes is of huge significance to develop advanced supercapacitors with commercial application prospects, which still remains challenging. Herein, high mass loading CoFe-prussian blue analogue (CoFe-PBA) electrodes are developed by a facile co-precipitation method using activated carbon cloth (ACC) as the flexible substrate. The homogeneous nanocube structure, large specific surface area (143.9 m2 g-1) and appropriate pore size distribution (3.4 nm) of the CoFe-PBA endow the as-prepared CoFe-PBA/ACC electrodes with low resistance and appealing ion diffusion characteristics. Typically, the high areal capacitance (1155.0 mF cm-2 at 0.5 mA cm-2) is obtained for high mass loading CoFe-PBA/ACC electrodes (9.7 mg cm-2). Furthermore, symmetrical flexible supercapacitors (FSCs) are constructed using CoFe-PBA/ACC electrodes and Na2SO4/polyving alcohol (Na2SO4/PVA) gel electrolyte, achieving superior stability (85.6% capacitance retention after 5,000 cycles), maximum energy density of 33.8 µWh cm-2 at 200.0 µW cm-2 and promising mechanical flexibility. This work is expected to offer inspirations for the development of high mass loading and additive-free electrodes for FSCs.

A highly sensitive upconversion nanoparticles@zeolitic imidazolate frameworks fluorescent nanoprobe for gallic acid analysis.

In this work, a core-shell structured upconversion nanoparticles@zeolitic imidazolate frameworks (ZIF-8) fluorescent nanoprobe (NaErF4:Tm@SiO2@ZIF-8) has been designed for the detection of gallic acid (GA). The mechanism is according to the 3, 3', 5, 5'-tetramethylbenzidine (TMB) can be oxidized to oxidized TMB (oxTMB) by Ag+. Under 980 nm laser excitation, NaErF4:Tm@SiO2@ZIF-8 can emit red light at 652 nm, which have a good overlap with the absorption spectra of oxTMB, resulting in the fluorescence quenching at 652 nm. Continually adding GA into the above solution, oxTMB will restore to TMB, and the fluorescence intensity at 652 nm gradually recovers, which can realize the detection towards GA. The linear detection range of GA is from 0 to 30 µM, and the limit of detection (LOD) of GA is 0.35 µM. The ZIF-8 can largely enhance the sensitivity of the nanoprobe, due to the physical absorption and the electrostatic attraction between ZIF-8 and the oxTMB. More importantly, this is the first time to realize the detection of GA with high sensitivity by using upconversion fluorescence. Besides, we have realized the analysis of GA in real samples, which certify the feasible of the nanoprobe in potential applications.

A novel core-shell upconversion nanoparticles@zirconium-based metal organic framework fluorescent nanoprobe for efficient continuous detection of trace methylene blue and ferrous ions.

Herein, we have synthesized Gd2O3:Yb,Er@UiO-66-NH2 (UiO-66-NH2 represent a zirconium-based metal organic framework [Zr6O4(OH)4(ata)12], ata: 2-aminoterephthalate) core-shell composites to develop an upconversion fluorescent nanoprobe for efficient detection of trace methylene blue (MB) and ferrous ions (Fe2+). Due to the fluorescence of the nanoprobe can be quenched by MB based on inner filter effect, but gradually recover when contact with ·OH, which is generated from the reaction between H2O2 and Fe2+, we have achieved the detection of Fe2+. The detection linear range is from 1.78 to 15.8 µM, and the limit of detection (LOD) is 0.071 µM. Besides, in this process, we also simultaneously realize the detection of MB. The linear range of MB turn-off detection is 0-42.6 µM, and the LOD is 0.41 µM. To our knowledge, no example of using upconversion fluorescence probe for continuous detection of trace MB and Fe2+ has been reported for now, and test results are superior compared with most reported Fe2+ probes. Moreover, the combinations of upconversion nanoparticles (UCNPs) and the metal-organic frameworks (MOFs) have enhanced the selectivity and sensitivity of the probe towards MB and Fe2+. Therefore, we believe the designed upconversion fluorescent nanoprobe is a promising efficient tool in detecting MB and diagnose Fe2+ related diseases in the future.

Rare Earth Oxide Anchored Platinum Catalytic Site Coated Zeolitic Imidazolate Frameworks toward Enhancing Selective Hydrogenation.

Controlling and manipulating the self-assembly technology at the nanoscale has become a powerful strategy for improving chemical processes and further developing the conception of atom efficiency. Herein, an unexpected core-shell structured Gd2O3@Pt@ZIF-8 nanoreactor has been fabricated using the self-assembly strategy in which the firm Gd2O3 nanosupport anchored the highly active Pt nanoparticle coated porous zeolitic imidazolate framework (ZIF-8). The well-designed Gd2O3@Pt@ZIF-8 structure shows good performance in selective hydrogenation of aldehyde-, keto-, and nitro-compounds with full conversion (>99.9%) and superior selectivity (>95%). It showed the channel sieving effect of the ZIF-8 channels toward enhancing the catalytic selectivity. After being recycled eight times, their activity remains unchanged and their core-shell structure is kept intact. So, the outer ZIF-8 membranes not only prevent Pt nanoparticles from agglomeration and slipping during a catalytic reaction but also maintain the original activity and long-term stability compared to the Gd2O3@Pt catalyst. The self-assembly strategy demonstrated here will allow the development of other highly active, stable, and selective catalysts for important but challenging transformations.

A new cobalt metal-organic framework as a substrate for Pd nanoparticles applied in high-efficiency nitro phenol degradation and cinnamaldehyde hydrogenation.

In recent years, attributed to the excellent catalytic performance of precious metal materials, metal nanoparticles@MOF catalyst has been a popular research direction. Herein, we have synthesized a new 3D cobalt metal-organic framework [Co(TATAB)(344-pytpy)·DMF]n(H3TATAB = 4,4',4″-s-triazine-1,3,5-triyltri-p-aminobenzoic acid; 344-pytpy = 4'-(3-pyridyl)-4,2':6',4″-terpyridine)(1)(P1) by solvothermal method. Its crystal structure was determined with single-crystal X-ray diffraction (SC-XRD) techniques. The final composite Pd-NPs@1 catalyst was synthesized by a reduction method. The catalyst showed high catalytic performance and high recycling stability for nitrophenol degradation and cinnamaldehyde hydrogenation reaction.

A dual-responsive luminescent metal-organic framework as a recyclable luminescent probe for the highly effective detection of pyrophosphate and nitrofurantoin.

Pyrophosphate (PPi) is a significant biological anion, and its abnormal level in the human body is regarded as a signal of some diseases. Herein, we developed a method for the detection of PPi using a luminescent ZTMOF-1 via the luminescence turn-on effect. PPi formed hydrogen bonds with the phenyl and pyridine rings in the framework, and ZTMOF-1 could discriminately detect PPi among other phosphorus oxides in both an aqueous solution and a physiological environment. In addition, to the best of our knowledge, this is the first report on the use of a regenerable MOF-based luminescent sensor for the detection of PPi. Moreover, ZTMOF-1 showed an excellent luminescence quenching response to nitrofurantoin (NFT) over other drugs with the detection limit of 0.175 µM. This study presents a dual-responsive regenerable luminescent probe for the detection of PPi and NFT.