Wence Xu

Nanoporous CuS with excellent photocatalytic property.

We present the rational synthesis of nanoporous CuS for the first time by chemical dealloying method. The morphologies of the CuS catalysts are controlled by the composition of the original amorphous alloys. Nanoporous Cu2S is firstly formed during the chemical dealloying process, and then the Cu2S transforms into CuS. The nanoporous CuS exhibits excellent photocatalytic activity for the degradation of the methylene blue (MB), methyl orange (MO) and rhodamine B (RhB). The excellent photocatalytic activity of the nanoporous CuS is mainly attributed to the large specific surface area, high adsorbing capacity of dyes and low recombination of the photo generated electrons and holes. In the photo degradation process, both chemical and photo generated hydroxyl radicals are generated. The hydroxyl radicals are favor in the oxidation of the dye molecules. The present modified dealloying method may be extended for the preparation of other porous metal sulfide nanostructures.

Earth-abundant amorphous catalysts for electrolysis of water

The generation of hydrogen through the electrolysis of water has attracted attention as a promising way to produce and store energy using renewable energy sources. In this process, a catalyst is very important to achieve a high-energy conversion efficiency for the electrolysis of water. A good catalyst for water electrolysis should exhibit high catalytic activity, good stability, low cost and good scalability. Much research has been devoted to developing efficient catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Traditionally, it has been accepted that a material with high crystallinity is important to serve as a good catalyst for HER and/or OER. Recently, catalysts for HER and/or OER in the electrolysis of water splitting based on amorphous materials have received much interest in the scientific community owing to the abundant unsaturated active sites on the amorphous surface, which form catalytic centers for the reaction of the electrolysis of water. We summarize the recent advances of amorphous catalysts for HER, OER and overall water splitting by electrolysis and the related fundamental chemical reactions involved in the electrolysis of water. The current challenges confronting the electrolysis of water and the development of more efficient amorphous catalysts are also discussed.

A nanoporous metal phosphide catalyst for bifunctional water splitting

The development of high-performance earth-abundant bifunctional electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is highly desirable, but remains a significant challenge. Herein, a type of content-controllable amorphous Ni–Fe–P catalyst with a bicontinuous nanostructure has been reported to be useful as a bifunctional electrocatalyst for overall water splitting. np-(NixFe1−x)4P5 is prepared simply by an electrochemical dealloying method. Owing to the bicontinuous nanostructure, amorphous atomic arrangement, metallic nature, and the substitution of Ni by Fe, np-(Ni0.67Fe0.33)4P5 exhibits excellent catalytic performance with the overpotentials of 245 mV and 120 mV at the current density of 10 mA cm−2 for OER and HER in 1 M KOH, respectively. Furthermore, the np-(Ni0.67Fe0.33)4P5 catalyst as both an anode and a cathode shows a high current density of 10 mA cm−2 at a low potential of 1.62 V in a two-electrode water electrolysis system with excellent stability for 20 h.

A highly efficient electrocatalyst based on amorphous Pd–Cu–S material for hydrogen evolution reaction

Hydrogen evolution reactions (HER) through water splitting draws tremendous attention as a way for generating clean energy. In this process, developing cost-effective, efficient non-Pt electrocatalysts is highly important for HER practical applications. In this work, we demonstrate a highly efficient and stable electrocatalyst based on amorphous Pd–Cu–S material. We found that the existence of abundant bridging S22− and apical S2− species and charge redistribution between Pd and Cu atoms in the material provided significantly enhanced electrocatalytic activity for HER, leading to a small overpotential of 58 mV at 10 mA cm−2 and a Tafel slope of only 35 mV dec−1, which is close to commercial Pt-based catalysts. Furthermore, the material demonstrated excellent electrochemical durability with no performance decrease in HER for 48 h even in 7 M H2SO4 solution, indicating its great potential as a non-Pt catalyst for HER water splitting.

Preparation and electrocatalytic performance of the Pt supported on the alkali-treated nanoporous TiO2 material

In this work, we prepared a Pt/TiO2 electrocatalyst for methanol electrooxidation. The Pt nanoparticles were loaded on the alkali-treated nanoporous TiO2 by a convenient deposition method. The morphology of the nanoporous TiO2 was depended on the alkali treatment time. After 15-min alkali treatment, the flocculent-liked nanostructure was formed, and the specific surface area of the material was the largest. The amounts as well as the size and distribution of Pt nanoparticles were controlled by loading times. The catalytic activities of the catalysts toward methanol electrooxidation were tested in the alkaline condition. The alkali treatment time and chemical loading time were the key factors that influenced the catalytic activities. The optimal catalytic activity was achieved when the loading time was six.