Oxygen vacancies enhanced electrocatalytic water splitting of P-FeMoO4 initiated via phosphorus doping.

Transition metal oxides (TMOs) are abundant and cost-effective materials. However, poor conductivity and low intrinsic activity limit their application in electrolyzed water catalysts. Herein, we prepared P-FeMoO4 in situ on nickel foam (P-FMO@NF) by phosphorylation-modified FeMoO4 to optimize its electrocatalytic properties. Interestingly, phosphorus doping is accompanied by the generation of oxygen vacancies and surface phosphates. Oxygen vacancies accelerated Mo dissolution during the oxygen evolution reaction (OER), leading to the rapid reconfiguration of P-FMO@NF to FeOOH and regulating the electronic structure of P-FMO@NF. The formation of phosphates is caused by the substitution of some molybdates with phosphates, which further increases the amount of oxygen vacancies. Hence, the OER overpotential of P-FMO@NF at a current density of 10 mA cm-2 is only 206 mV, and the hydrogen evolution reaction (HER) overpotential is 154 mV. It was assembled into a water splitting cell with a voltage of just 1.59 V at 10 mA cm-2 and shows excellent stability over 50 h. These excellent electrocatalytic properties are mainly attributed to the oxygen vacancies, which improve the interfacial charge transfer properties of the catalysts. This study provides new insights into phosphorus doping and offers a new perspective on the design of electrocatalysts.

CuOx/Cu nanorod skeleton supported Ru-doped CoO/NC nanocomposites for overall water splitting.

High overpotential and low stability are major challenges for hydrogen evolution reaction (HER)/oxygen evolution reaction (OER). Tuning the electronic structure of catalysts is regarded as a core strategy to enhance catalytic activity. Herein, we report CuOx/Cu nanorod skeleton supported Ru doped cobalt oxide/nitrogen-doped carbon nanocomposites (Ru-CoO/NC/CuOx/Cu, denoted as RCUF) as bifunctional catalysis. The one-dimensional/three-dimensional (1D/3D) nanostructure and defect-rich amorphous/crystalline phases of RCUF facilitates active site exposure and electron transport. Experimental characterization and density functional theory (DFT) calculation results indicate that Ru doping can optimize the electronic structure, which accelerates the water dissociation process and reduces the Gibbs free energy of the reaction intermediates. As expected, the optimal RCUF-900 exhibits low overpotential (25/205 mV at 10 mA cm-2) and high stability (100/100 h) for HER/OER. RCUF-900 has low voltage (1.54 V at 10 mA cm-2) and high stability (100 h) for overall water splitting. This work provides new insights into the design of advanced catalysts for overall water splitting.

Surface reconstruction of RuO2/Co3O4 amorphous-crystalline heterointerface for efficient overall water splitting.

The rational construction of amorphous-crystalline heterointerface can effectively improve the activity and stability of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, RuO2/Co3O4 (RCO) amorphous-crystalline heterointerface is prepared via oxidation method. The optimal RCO-10 exhibits low overpotentials of 57 and 231 mV for HER and OER at 10 mA cm-2, respectively. Experimental characterization and density functional theory (DFT) results show that the optimized electronic structure and surface reconstruction endow RCO-10 with excellent catalytic activity. DFT results show that electrons transfer from RuO2 to Co3O4 through the amorphous-crystalline heterointerface, achieving electron redistribution and moving the d-band center upward, which optimizes the adsorption free energy of the hydrogen reaction intermediate. Moreover, the reconstructed Ru/Co(OH)2 during the HER process has low hydrogen adsorption free energy to enhance HER activity. The reconstructed RuO2/CoOOH during the OER process has a low energy barrier for the elementary reaction (O*→*OOH) to enhance OER activity. Furthermore, RCO-10 requires only 1.50 V to drive 10 mA cm-2 and maintains stability over 200 h for overall water splitting. Meanwhile, RCO-10 displays stability for 48 h in alkaline solutions containing 0.5 M NaCl. The amorphous-crystalline heterointerface may bring new breakthroughs in the design of efficient and stable catalysts.

Surface-Diluted LiMn6 Superstructure Units Utilizing PO4 3- Confined Ni-Doping Sites to Stabilize Li-Rich Layered Oxides.

Serious capacity and voltage degradation of Li-rich layered oxides (LLOs) caused by severe interfacial side reactions (ISR), structural instability, and transition metal (TM) dissolution during charge/discharge need to be urgently resolved. Here, it is proposed for the inaugural time that the confinement effect of PO4 3- dilutes the LiMn6 superstructure units on the surface of LLOs, while deriving a stable interface with phosphate compounds and spinel species. Combining theoretical calculations, diffraction, spectroscopy, and micrography, an in-depth investigation of the mechanism is performed. The results show that the modified LLO exhibits excellent anionic/cationic redox reversibility and ultra-high cycling stability. The capacity retention is increased from 72.4% to 95.4%, and the voltage decay is suppressed from 2.48 to 1.29 mV cycle-1 after 300 cycles at 1 C. It also has stable long cycling performance, with capacity retention improved from 40.2% to 81.9% after 500 cycles at 2 C. The excellent electrochemical performance is attributed to the diluted superstructure units on the surface of LLO inhibiting the TM migration in the intralayer and interlayer. Moreover, the stable interfacial layers alleviate the occurrence of ISR and TM dissolution. Therefore, this strategy can give some important insights into the development of highly stable LLOs.

Ag-Au Core-Shell Triangular Nanoprisms for Improving p-g-C3N4 Photocatalytic Hydrogen Production.

Ag-Au core-shell triangular nanoprisms (Ag@Au TNPs) have aroused extensive research interest in the field of hydrogen evolution reaction (HER) due to their strong plasmon effect and stability. Here, Ag@Au TNPs were fabricated by the galvanic-free replacement method. Then, we loaded them on protonated g-C3N4 nanoprisms (P-CN) by the electrostatic self-assembly method as an efficient plasmonic photocatalyst for HER. The hydrogen production rate of Ag@Au TNPs/P-CN (4.52 mmol/g/h) is 4.1 times higher than that of P-CN (1.11 mmol/g/h) under simulated sunlight irradiation, making it the most competitive material for water splitting. The formed Schottky junction helps to trap the hot electrons generated from Ag@Au TNPs, and the well-preserved tips of the Ag@Au TNPs can effectively generate an electromagnetic field to inhibit the photogenerated electron-holes pairs recombination. This study suggests that the rational design of Ag@Au TNPs by the galvanic-free replacement method is an effective co-catalyst for HER and boosting the additional combination of plasmonic metals and catalyst metals for the enhancement to HER.

Berberine alleviates preeclampsia possibly by regulating the expression of interleukin-2/interleukin-10 and Bcl-2/Bax.

The present study is to investigate the effect of berberine on the expression of inflammatory factors interleukin (IL)-2 and IL-10, and the expression of apoptosis proteins Bcl-2 and Bax. A total of 70 SD rats were randomly divided into 7 equal groups, including normal non-pregnant group, normal pregnant group, preeclampsia group, preeclampsia + berberine (50, 100, and 200 mg/kg/day) groups, and preeclampsia + nifedipine (20 mg/kg/day) group. Blood pressure was measured before pregnancy, and on day 15 and 21 of pregnancy. Urines before pregnancy and on day 15 and 21 of pregnancy were collected for the determination of urine protein levels. Peripheral blood was collected from all rats on day 21 of pregnancy to measure the levels of blood urea nitrogen and creatinine. On day 21 of pregnancy, the weight of fetuses and placentas, and the number of normal fetuses were determined. Enzyme-linked immunosorbent assay was performed to determine the levels of IL-2 and IL-10 in plasma. Western blotting was used to measure the expression of Bcl-2 and Bax proteins in placenta of rats with preeclampsia. Treatment with berberine for seven days reduced blood pressure, urine proteins levels, and kidney function in rats with preeclampsia. Berberine improved the number of normal fetuses and the weight of fetuses and placentas from rats with preeclampsia. Berberine up-regulated IL-10 and down-regulated IL-2 in the peripheral blood of SD rats with preeclampsia. Berberine up-regulated Bcl-2 and down-regulated Bax in the placenta of SD rats with preeclampsia. Berberine increases the number and weight of normal fetuses in rats with preeclampsia, possibly by regulating the balance of IL-2 and IL-10, and inhibiting apoptosis.