ABSTRACT
Exploring an efficient and robust electrocatalyst for hydrogen evolution reaction (HER) at high pH and temperature holds the key to the industrial application of alkaline water electrolysis (AWE). Herein, we design an open tunnel structure by dealloying a series of Laves phase intermetallics, i.e., MCo2 and MRu0.25Co1.75 (M = Sc and Zr). The dealloying process can induce a zeolite-like metal framework for ScCo2 and ScRu0.25Co1.75 by stripping Sc metal from the center of a tunnel structure. This structural engineering significantly lowers their overpotentials at a current density of 500 mA/cm2 (η500) ca. 80 mV in 1.0 M KOH. Through a simple process, ScRu0.25Co1.75 can be easily decorated on a carbon cloth substrate and only requires 132 mV to reach 500 mA/cm2. More importantly it can maintain activity over 1000 h in industrial conditions (6.0 M KOH at 333 K), showing its potential for practical industrial applications.
ABSTRACT
The family of bimetallic oxides, chalcogenides, and pnictides is regarded as a promising and cost-effective oxygen evolution reaction (OER) catalyst compared to noble metals. For practical utilizations, lowering the overpotential and improving the stability of electrocatalysts for the OER are highly important. However, the particular roles of active sites and their surrounding moieties in these catalysts, especially in an aqueous system during the reaction (in situ working conditions), are still ambiguous. Thanks to the well-developed techniques of X-ray diffraction and absorption spectroscopy based on a synchrotron light source, the local structural transformation of these catalysts can be evidently revealed by in situ experiments. Herein, the research on 3d transition metal oxides and chalcogenides used for the OER is enumerated with their corresponding in situ characterization and electrochemical (EC) performances. We generalize the universality of phase transition in the catalysts from the pristine/as-prepared structure to the specific active species during the OER and propose a synergistic effect between the active sites and subsidiary sites on the surface of the catalysts.
ABSTRACT
Visible light-induced photocatalysis is potentially advantageous and could be an efficient approach to degrade contaminants because it can be used to selectively target specific wavelength for decomposition of organic contaminants in water and wastewater. This study demonstrates the photodegradation of sulfamethoxazole (SMX) using [Pt(3,3'-dicarboxy-2,2'-bpy)(1,2-benzenedithiolate)] (Complex 1)-sensitized and [Pt(4,4'-dicarboxy-2,2'-bpy)(1,2-benzenedithiolate)] (Complex 2)-sensitized titanium dioxide (TiO2) under blue or yellow light (420 or 580 nm, respectively) irradiation in water. The Complex 1-sensitized TiO2 photocatalytic oxidation of SMX reached almost 100 % removal under 420 nm irradiation for 3 h in water. In addition, the formation of hydroxyl radicals can be facilitated by bubbling O2 during the photodegradation in which an effective decomposition of SMX was observed. Based on HPLC and UV-Vis studies of the decomposed products, it was found that SMX underwent cleavage of aromatic rings during the photodegradation process.
