Search

Pulsed electrodeposition has been introduced to deposit ultrathin flakes of Co3O4 nanocrystals on ZnO nanorods. By fixing the seeding process, the scaffolding function of ZnO nanorods was studied by varying deposition times (30 s, 60 s, and 90 s) of Co3O4 at a nucleation current of −1.0 mA cm−2. The amount of deposited Co3O4 has a strong influence on the oxygen evolution performance with ZnO scaffolds. To deliver a current density of 10.0 mA cm−2 in neutral solutions (0.5 M K2SO4), the presence of ZnO scaffold electrodes negatively shifted the overpotential by ∼200 mV. In particular, the Co3O4/ZnO hybrid nanostructured electrode (60 s) exhibits the lowest onset potential of 1.5 V (vs. reversible hydrogen electrode, RHE). Electrochemical impedance spectra and double layer capacitance showed that the enhanced oxygen evolution activities originated from the improved charge transfer capability and the increased electrochemically active interface between Co3O4 and ZnO. ZnO nanorods arrays serve as an effective scaffold for highly dispersed pulsed‐electrodeposited Co3O4. The increased electrochemically active area at the intimate interface between Co3O4 and ZnO accounts for the material's excellent performance in the oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

The electronic coordination configuration of metal active sites and the reaction mechanism were investigated by constructing homo-diatomic Fe sites for visible-light-assisted heterogeneous peroxymonosulfate (PMS) activation. A novel Fe 2 N 6 catalyst was synthesized by selecting uniform pyridinic-N of graphitic carbon nitride (g-C 3 N 4 ) as anchoring sites. The results demonstrated that homo-diatomic Fe sites modulated the d-band center and electron delocalization and thus enhanced the PMS activation kinetics (3.58 times vs single-atom Fe catalyst) with k obs of 0.111 min -1 owing to the synergistic effect between adjacent Fe atoms. New Fe-Fe coordination significantly decreased the contribution of the antibonding state in the Fe-O bond due to the coupling of the Fe-3d orbitals, which facilitated the O-O bond cleavage of the Fe 2 -HOO-SO 3 complex with a reduced thermodynamic energy barrier of only -0.29 eV. This work provided comprehensive mechanistic insights into developing homo-diatomic catalysts governed by the coordination configuration and radical pathway for efficient heterogeneous PMS catalysis.

The destruction of perfluorooctanoic acid (PFOA) from outside was inhibited by the "barrel spiral" barrier, but the construction of the photocatalyst-PFOA complex provided a direct attack on photogenerated reactive species (RSs). Here, we investigated the bridging ability of bismuth oxychalcogenide (Bi 2 O 2 X) for constructing an effective photocarrier pathway to PFOA. The experimental results and DFT calculations showed that a more intense internal access of Bi 2 O 2 Se was built via the terminal carboxylate tail, and the weaker electrostatic interaction of Bi-Se bonds helped realize the smaller band gap and slower recombination of photocarriers, thereby inhibiting the invalid annihilation of holes with H 2 O and facilitating the transformation of electrons to O 2 -• . The pseudo-first-order rate coefficient ( k obs ) was 2 and 4 times higher than Bi 2 O 2 S and TiO 2 , respectively, showing the outstanding photocatalytic activity of Bi 2 O 2 Se. A broad pH (4-8) adaptability of Bi 2 O 2 Se was observed for defluorination, especially in alkali condition. This new understanding may inspire the development of Se-coordinated catalysts.

Herein, we demonstrated the construction of three-dimensional (3D) cerium oxide (CeO x )/SBA-16 nanocomposites for efficient removal of bisphenol A (BPA) via a catalytic ozonation, with a high BPA mineralization up to 60.9% in 90 min. On one hand, the CeO x /SBA-16 mesoporous structured materials presented large surface area and uniform pore distribution, which was conducive to the adsorption of transformation by-products (TBPs) and then, the mass transfer. On the other hand, CeO x /SBA-16 could enhance the ozone utilization efficiency and meanwhile facilitate the formation of OH, the main reactive oxygen species. Through the exploration of dissoluble organic matters and the identification of the reaction intermediates, two BPA degradation pathways were proposed. This approach reported here will benefit the design and construction of mesoporous structured materials for catalytic elimination of hazards to remediate the environment., (Copyright © 2021 Elsevier Ltd. All rights reserved.)