Shuo Feng

Two-Dimensional N,S-Codoped Carbon/Co9S8 Catalysts Derived from Co(OH)2 Nanosheets for Oxygen Reduction Reaction

The development of highly active and cost-efficient electrocatalysts for the oxygen reduction reaction (ORR) is of great importance in a wide range of clean energy devices, including fuel cells and metal-air batteries. Herein, the simultaneous formation of Co9S8 and N,S-codoped carbon with high ORR catalytic activity was achieved in an efficient strategy with a dual templates system. First, Co(OH)2 nanosheets and tetraethyl orthosilicate were utilized to direct the formation of two-dimensional carbon precursors, which were then dispersed into thiourea solution. After subsequent pyrolysis and template removal, N,S-codoped porous carbon-sheet-confined Co9S8 catalysts (Co9S8/NSC) were obtained. Owing to the morphological and compositional advantages as well as the synergistic effects, the resultant Co9S8/NSC catalysts with a modified doping level and pyrolysis degree exhibit superior ORR catalytic activity and long-term stability compared with the state-of-the-art Pt/C catalysts in alkaline media. Remarkably, the as-prepared carbon composites also reveal exceptional tolerance of methanol, indicating their potential applications in fuel cells.

Interconnected Fe, S, N-Codoped Hollow and Porous Carbon Nanorods as Efficient Electrocatalysts for the Oxygen Reduction Reaction

As promising precious metal-free oxygen reduction reaction (ORR) electrocatalysts, Fe-N-C catalysts still face a great challenge to meet the requirement of practical applications. In this study, Fe, S, N-codoped hollow and porous carbon nanorods (Fe-S-N HPCNRs) were designed with the aim of improving the performance of Fe-N-C catalysts from the perspective of composition and structure. They were successfully prepared using cysteine, Fe2+ salt, and polydopamine-encapsulated ZnO nanorods (ZnO NRs@PDA) as precursors by a pyrolysis-acid etching strategy. The hollow and porous structure and composition of Fe, S, N, and C were verified by transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller, and X-ray photoelectron spectroscopy tests. At the optimum ratio of ZnO NRs@PDA/cysteine and pyrolysis temperature, the Fe-S-N HPCNRs display higher ORR activities than the control samples which are lack of one of the precursors. Electrochemical tests show that the ORR follows a 4e pathway with the Fe-S-N HPCNRs. In addition, the long-term stability and methanol tolerance of Fe-S-N HPCNRs are good and superior to those of 20 wt % Pt/C.

Porous Carbon‐Hosted Atomically Dispersed Iron–Nitrogen Moiety as Enhanced Electrocatalysts for Oxygen Reduction Reaction in a Wide Range of pH

As one of the alternatives to replace precious metal catalysts, transition-metal-nitrogen-carbon (M-N-C) electrocatalysts have attracted great research interest due to their low cost and good catalytic activities. Despite nanostructured M-N-C catalysts can achieve good electrochemical performances, they are vulnerable to aggregation and insufficient catalytic sites upon continuous catalytic reaction. In this work, metal-organic frameworks derived porous single-atom electrocatalysts (SAEs) were successfully prepared by simple pyrolysis procedure without any further posttreatment. Combining the X-ray absorption near-edge spectroscopy and electrochemical measurements, the SAEs have been identified with superior oxygen reduction reaction (ORR) activity and stability compared with Pt/C catalysts in alkaline condition. More impressively, the SAEs also show excellent ORR electrocatalytic performance in both acid and neutral media. This study of nonprecious catalysts provides new insights on nanoengineering catalytically active sites and porous structures for nonprecious metal ORR catalysis in a wide range of pH.

One-step synthesis of carbon nanosheet-decorated carbon nanofibers as a 3D interconnected porous carbon scaffold for lithium–sulfur batteries

Among the emerging energy storage methods, lithium–sulfur (LIS) batteries have drawn plenty of attention due to their high theoretical energy density, low cost and environmental benignity. Nevertheless, the insulating nature of sulfur and notorious polysulfide shuttling result in low sulfur utilization and short cycling life. In recent years, various carbon structures have been reported as effective sulfur hosts to tolerate volume expansion, prevent polysulfide dissolution and enhance electrical conductivity. It is hard for carbon materials, however, to satisfy all these aspects with a simple structural design. Thus, developing hierarchical carbon structures that serve as a multi-functional host is necessary for high-performance LIS batteries. Herein, we reported a facile method to prepare a three-dimensional carbon nanofiber (3DCNF) through a hydrothermal reaction. With the structural advantages, the 3DCNF and sulfur composite delivered a capacity as high as 1266 and 977 mA h g−1 at 0.1 and 0.5 C, respectively. After 500 cycles at 0.5 C, it still retains a capacity of 607 mA h g−1 (0.07% capacity fading per cycle), exhibiting excellent cycling capability.

Ultrathin dendritic IrTe nanotubes for an efficient oxygen evolution reaction in a wide pH range

The shape control of Ir-based nanostructured materials, which are considered as the state-of-the-art anode electrocatalyst candidates toward the oxygen evolution reaction (OER), has been rarely reported. Here, we reported an efficient synthesis of ultrathin dendritic IrTe nanotubes (NTs) via a galvanic replacement reaction using Te nanowires as the template at 190xa0°C for 1 h. The as-obtained IrTe NTs exhibited improved electrocatalytic activity and stability toward the OER with a much smaller overpotential of 290 mV and Tafel slope of 60.3 mV dec−1 to attain a current density of 10 mA cm−2 in acidic medium, compared with commercial IrO2 nanoparticles. Moreover, IrTe NTs also demonstrated enhanced electrocatalytic performances in neutral and alkaline media. The outstanding electrochemical properties of IrTe NTs in a wide pH range hold great promise in energy storage and conversion devices.

Kinetically controlled synthesis of AuPt bi-metallic aerogels and their enhanced electrocatalytic performances

Recently, metallic hydrogels/aerogels have received tremendous attention due to their unique physical and chemical properties. For the first time, we reported the successful synthesis of AuPtx metallic hydrogels at 60 °C in 2–4 h. Surfactant-free AuPt5 metallic hydrogels displayed enhanced electrocatalytic activities and stabilities toward methanol oxidation.