Construction of ZIF-67-On-UiO-66 Catalysts as a Platform for Efficient Overall Water Splitting

Abstract

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.

Enhanced Visible-Light-Induced Photocatalytic Activity in M(III)Salophen-Decorated TiO2 Nanoparticles for Heterogeneous Degradation of Organic Dyes

“…Quenching of the PL intensity (excited at 355 nm) by 71% obviously showed the efficient electron–hole separation resulting from the charge transfer between the TiO 2 core and M­(salophen)­Cl through the SAPy linker, which is expected to increase the photochemical activity of the fabricated hybrid (Figure B) . This was further supported by electrochemical impedance spectroscopy (EIS) measurements (Figure C) . Typically, a semicircle with a larger radius refers to a higher charge transfer resistance of the electrode.…”

“…(A) DRS spectra (black curve) and the Tauc plot (inset) of Fe­(III)­(salophen)­Cl@SAPy/TiO 2 , and its action spectra (blue dots) for RhB degradation under CFL light. (B) PL spectra of TiO 2 and Fe­(III)­(salophen)­Cl@SAPy/TiO 2 excited at 355 nm; (C) electrochemical impedance spectroscopy using a three-electrode assembly in 2.5 mM K 4 [FeCN 6 ]·3H 2 O, 2.5 mM K 3 [FeCN 6 ], and 0.5 M Na 2 SO 4 solution; (D) dependence of the photodegradation of RhB on the irradiation wavelength catalyzed by Fe­(salophen)­Cl@SAPy/TiO 2 ; and (E) the action spectra of the photocatalytic reaction in which the light-driven conversion is plotted against the irradiation wavelength. The reactions were exposed to CFL light equipped with cutoff filters for 120 min under optimized conditions.…”

“…24 This was further supported by electrochemical impedance spectroscopy (EIS) measurements (Figure 6C). 64 Typically, a semicircle with a larger radius refers to a higher charge transfer resistance of the electrode. Therefore, the EIS result depicted in Figure 6C concluded that the charge transfer resistance (R ct ) of the Fe(salophen)Cl@SAPy/TiO 2 electrode is smaller than that of TiO 2 , confirming the higher conductivity and charge transfer in the as-prepared hybrid than those in bare TiO 2 .…”

Hollow Starlike Ag/CoMo-LDH Heterojunction with a Tunable d-Band Center for Boosting Oxygen Evolution Reaction Electrocatalysis

“…Especially in recent decades, the evolution of clean energy has become extremely urgent due to worsening environmental issues and the increasing demand for green life. − Hydrogen energy is one sustainable secondary energy alternative with unparalleled advantages, including facile transportation and storage, high energy density, and zero-pollution combustion, evoking the “ultimate energy source of the 21st century”. It also provides a splendid roadmap for achieving carbon peak and carbon neutrality. − …”

Fabrication of MIL‐101(Fe) on UiO‐66 as an Electrocatalyst for Enhanced Overall Water Splitting

“…They successfully used it for the bifunctional system that is highly efficient and durable for both OER and HER in an alkaline medium. [19] Mei et al were able to prepare CoP@FeÀ CoP core-shelled nanorod arrays with nitrogen-doped carbon incorporation on Ni foam (designated as CoP@FeÀ CoP/NC/NF) using a phosphorization approach involving ZIF-67@CoÀ Fe Prussian blue analogue (referred to as ZIF-67@CoFeÀ PBA) as the precursor. It was then employed for an alkaline water-splitting process achieving remarkable overpotentials of 97 mV for HER and 270 mV for OER at current densities of 100 mA/cm 2 .…”