Synthesis of Pure Thiophene-Sulfur-Doped Graphene for an Oxygen Reduction Reaction with High Performance.

Various S-bonding configurations existing in sulfur-doped reduced graphene oxide (S-rGO) show different electronic structures and physiochemical properties. Thus, understanding the properties of unique S-bonding configurations requires the construction of S-rGO with only single configuration. Here, we synthesized S-rGO with a pure thiophene-sulfur configuration through a simple and low-cost hydrothermal method by simply controlling the oxidation degree of the graphene oxide (GO) precursor. Through the use of a GO precursor with a high content of C-O groups, pure doping of the thiophene-sulfur configuration in the rGO can be achieved. Further electrochemical characterization reveals an increased electrocatalytic activity of the pure thiophene-sulfur-doped S-rGO in the oxygen reduction reaction, indicating the important role of thiophene-sulfur. The present work deepens the understanding of the functions of doped nonmetal elements in carbon materials in electrocatalysis and helps in the design of high performance electrocatalysts.

Recent advances in MoS2-based materials for electrocatalysis.

The increasing energy demand and related environmental issues have drawn great attention worldwide, thus necessitating the development of sustainable technologies to preserve the ecosystems for future generations. Electrocatalysts for energy-conversion reactions such as the hydrogen evolution reaction (HER), nitrogen reduction reaction (NRR), and carbon dioxide reduction reaction (CO2RR) are at the heart of these renewable energy technologies, but they suffer from sluggish kinetics due to the multistep electron and mass transfer. State-of-the-art catalysts are thus highly desired to boost the conversion efficiencies, which are still inadequate. Recently, as a typical transition metal dichalcogenide, molybdenum disulfide (MoS2) with unique physicochemical properties has been verified as a promising material for catalyzing key electrochemical reactions (i.e., HER, NRR, and CO2RR), presenting excellent performances. Therefore, in this review, we give insight into the structure and synthetic strategies of MoS2. Recent advances in MoS2-based materials for the three key electrochemical reactions are briefly summarized. Open challenges and perspectives of MoS2-based electrocatalysts toward HER, NRR, and CO2RR are also outlined.

Unusual Hollow Al2O3 Nanofibers with Loofah-Like Skins: Intriguing Catalyst Supports for Thermal Stabilization of Pt Nanocrystals.

Recently, hollow nanofibers could be fabricated by coaxis electrospinning method or template method. However, they are limited to applications because of the hardship in actual preparation. In this work, hollow γ-Al2O3 nanofibers with loofah-like skins were first fabricated by using a single spinneret during electrospinning. These intriguing nanofibers were explored as new Pt supports with excellently sinter-resistant performance up to 500 °C, attributed to the unique loofah-like surface of γ-Al2O3 nanofibers and the strong metal-support interactions between Pt and γ-Al2O3. When applied in the catalytic reduction of p-nitrophenol, the Pt/γ-Al2O3 calcined at 500 °C exhibited 4-times higher reaction rate constant (6.8 s-1·mg-1) over free Pt nanocrystals.

Self-assembly of defect-rich graphene oxide nanosheets with Na2Ti3O7 nanowires and their superior absorptive capacity to toxic dyes.

Graphene sheets, a flexible 2D material with excellent absorptive capacity, have great potential as absorbing materials. However, this material has always suffered from irreversible aggregation and thus loses the abundant active sites and large surface area. In this paper, large-scale graphene oxide (GO) sheets were cut and reduced to tiny reduced graphene oxide (RGO) sheets by a cell-break sonicator, for producing numerous defects, which are the center of chemisorption. Furthermore, sodium titanate nanowires functioned as a framework to help to disperse the tiny RGO sheets uniformly. And, in turn, the flexible tiny RGO sheets glued robust nanowires into a free-standing membrane. This novel composite membrane exhibited an ultra-high decoloration efficiency of 99.8% of rhodamine B in a continuous flow mode, and an outstanding absorptive capability of 1.30 × 10-2 mol g-1 correlated to RGO content in batch reaction, which is about two orders of magnitude higher than other reported graphene-based absorbents. In addition, an efficient and feasible method without any heat treatment for regenerating the membrane is illustrated, and the recycled membrane retains superior decoloration efficiency. The excellent absorptive performance indicates the framework-based disperse strategy has great potential for the construction and application of defect-rich graphene.