A well-organized construction of hybrid metal− organic frameworks (MOFs) with exquisite structures is vital due to their potential applications. Herein, a novel hybrid nanostructure of UiO-66-on-ZIF-67, denoted as MZU-Co x Zr y (x and y represent the mass ratios of ZIF-67 and UiO-66, respectively), was successfully prepared by a simple method and showed a highly efficient and stable bifunctionality of both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in an alkaline medium. The MZU-Co 2.5 Zr 1 shows remarkable OER performance with a low overpotential of 252 mV and an overpotential of 172 mV @ 10 mA/cm 2 for HER in 1 mol/L KOH. With MZU-Co 2.5 Zr 1 as the cathode and anode, the integrated water decomposition device has achieved low total potentials of 1.56 V @ 10 mA/cm 2 and 1.59 V @ 30 mA/cm 2 , exhibiting its excellent performance of overall water splitting. Based on the experimental results, the mechanism of the superior electrocatalytic performance of MZU-Co x Zr y was discussed. This work supplies guidance for the rational design of nonprecious composites for energy conversion.

It is challenging to generate inexpensive and noble metal-free catalysts for efficient overall water splitting (OWS). To achieve this goal, suitable tuning of the structure and composition of electrocatalytic materials is a promising approach that has attracted much attention in recent years. Herein, novel hybrid amorphous ZIF-67@Co 3 (PO 4 ) 2 electrocatalysts with yolk−shell structures were prepared using a reflux method. It is demonstrated that yolk−shelled ZIF-67@Co 3 (PO 4 ) 2 is not only an active catalyst for the hydrogen evolution reaction (HER) but also an efficient catalyst for the oxygen evolution reaction (OER). The optimized composite electrode showed superior performance with low overpotentials of 73 and 334 mV @ 10 mA•cm −2 toward HER and OER, respectively, and a low potential of 1.62 V @ 10 mA• cm −2 and 1.66 V @ 30 mA•cm −2 in a practical OWS test under alkaline conditions. N−O bonds were formed to connect the two components of ZIF-67 and Co 3 (PO 4 ) 2 in the composite ZIF-67@Co 3 (PO 4 ) 2 , which indicates that the two components are synergistic but not isolated, and this synergistic effect may be one of the important reasons to boost the oxygen and hydrogen evolution performances of the hybrid. Based on experimental data, the high electrocatalytic performance was inferred to be related to the unique structure of ZIF-67, tuning the ability of Co 3 (PO 4 ) 2 and synergism between ZIF-67 and Co 3 (PO 4 ) 2 . The preparation strategy reported herein can be extended for the rational design and synthesis of cheap, active, and long-lasting bifunctional electrocatalysts for OWS and other renewable energy devices.

In this work, the construction of two heterojunction photocatalysts by coordinative anchoring of M(salophen)Cl complexes (M = Fe(III) and Mn(III)) to rutile TiO 2 through a silica−aminopyridine linker (SAPy) promotes the visible-light-assisted photodegradation of organic dyes. The degradation efficiency of both cationic rhodamine B (RhB) and anionic methyl orange (MO) dyes by Fe− and Mn−TiO 2 -based catalysts in the presence of H 2 O 2 under sunlight and low-wattage visible bulbs (12−18 W) is investigated. Anionic MO is more degradable than cationic RhB, and the Mn catalyst shows more activity than its Fe counterpart. Action spectra demonstrate the maximum apparent quantum efficiency (AQY) at 400−450 nm, confirming the visible-light-driven photocatalytic reaction. The enhanced photocatalytic activity might be attributed to the improved charge transfer in the heterojunction photocatalysts evidenced by photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) analyses. A radical pathway for the photodegradation of dyes is postulated based on scavenging experiments and spectral data. This work provides new opportunities for constructing highly efficient catalysts for wastewater treatment.

BACKGROUND: Composites of defluoridation adsorbents based on rare earths have attracted increasing interest recently, but most of them were amorphous. The main reason for this situation is that morphology control has not been paid enough attention, because the related preparation methods are relatively sparse. Consequently, novel preparation methods are urgently needed. RESULTS:In this study, a novel La-Zr-Ce tri-metal adsorbent with regular morphology was facilely synthesized. There were two morphological shapes in the composite. Nanoprisms of La 2 (C 2 O 4 ) 3 were decorated with mesoporous nanospheres of Fe 3 O 4 @m(ZrO 2 -CeO 2 ). The samples were investigated by energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). Several affecting factors such as initial fluoride concentration, contact time, coexisting anions and pH were studied in detail. The balance data were analyzed by Langmuir, Freundlich and Langmuir-Freundlich isotherm models. The nanocomposite had a maximum sorption capacity of 117.3 mg g −1 toward fluoride, which is among the highest ever reported for fluoride adsorbents. Furthermore, it had a wide applicable pH range of 2-10 and high anti-interference ability. The different functions of La 2 (C 2 O 4 ) 3 nanoprisms and Fe 3 O 4 @m(ZrO 2 -CeO 2 ) nanospheres in the composite have been elucidated. These two components were found to synergistically improve F − adsorption performance via their individual merits. CONCLUSION: The adsorbent had high potential to treat F − contaminants in real application, and the method reported here is considered to be helpful for developing more highly effective adsorbents. Adsorption isothermsAdsorption isotherms of the adsorbents were investigated by Langmuir (Equ. S2 in File S1), Freundlich (Equ. S3 in File S1) and J Chem Technol Biotechnol 2019; 94: 3650-3660 /jctb CONCLUSIONS A novel La-Zr-Ce tri-metal adsorbent with regular morphology was successfully synthesized by step-by-step precipitation methods and showed excellent fluoride removal performance. There J Chem Technol Biotechnol 2019; 94: 3650-3660

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