The demand on the highly efficient and low-cost cathodic electrocatalysts for commercialization of fuel cells is rapidly increasing. One smart route for obtaining these ideal electrocatalysts is extracting active carbon materials from natural and cheap biomass waste. Here, we prepared a novel nitrogen self-doped porous graphitic carbon nanosheets (NPGCNs-NaCl) derived from a nitrogen-rich pruning of Lycium barbarum L. using NaCl crystal as intercalation agent. The as-obtained NPGCNs-NaCl possessed porous structure, large surface area, increased content of nitrogen and high graphitic carbon, and thus making it with high electrocatalytic activity for oxygen reduction reaction (ORR). Most importantly, significantly enhanced stability and tolerance against methanol were observed compared with commercial Pt/C catalyst in alkaline solution. This work is believed to open a new avenue for manufacturing advanced and low-cost ORR electrocatalysts in fuel cells from biomass waste.

Porous MnO as a non-noble metal oxygen reduction reaction (ORR) electrocatalyst was prepared by a simple sonochemical route. The as-prepared porous MnO exhibited higher electrocatalytic activity, superior stability and better methanol tolerance than commercial Pt/C catalyst in alkaline media. Furthermore, the ORR proceeded via a nearly four-electron pathway. Cyclic voltammetry (CV) and rotating-disk electrode (RDE) measurements verified that the ORR enhancement was attributed to the porous structure and good dispersity, which facilitated sufficient transport of ions, electrons, O and other reactants in the process of ORR. The results indicated that a facile and feasible sonochemical route could be used to prepare highly active porous MnO electrocatalyst for ORR, which might be promising for direct methanol fuel cells.

For the alkaline fuel cell cathode reaction, it is very essential to develop novel catalysts with superior catalytic properties. Here, we report the synthesis of highly active and stable MoS/Pd composites for the oxygen reduction reaction (ORR), via a simple, eco-friendly sonochemical method. The bulk MoS was first transformed into single and few layers MoS nanosheets through ultrasonic exfoliation. Then the exfoliated MoS nanosheets served as supporting materials for the nucleation and further in-situ growth of Pd nanoparticles to form MoS/Pd composites via ultrasonic irradiation. Cyclic voltammetry and rotating disk voltammetry measurements demonstrate that as-prepared MoS/Pd composites which provides a direct four-electron pathway for the ORR, have better electrocatalytic activity, long-term operation stability than commercial Pt/C catalyst. We expect that the present work would provide a promising strategy for the development of efficient oxygen reduction electrocatalyst. In addition, this study can also be extended to the preparation of other hybrid with desirable morphologies and functions.

Highly active and inexpensive electrocatalysts are critical for metal-O 2 batteries or fuel cells. In the present study, we synthesized single boron nitride nanosheet-supported palladium (BN/Pd) composites via a simple sonochemical method. The properties of the synthesized products were studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), SEM energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The as-prepared BN/Pd composites showed favorable kinetics (four-electron transfer), high activity and excellent durability for the oxygen reduction reaction (ORR) in alkaline media. The catalyst also exhibited strong electrocatalytic activity and excellent long-term durability for formic acid oxidation (FAO) in acidic media. Notably, compared with the commercial Pt/C catalyst, the synthesized catalyst exhibited superior performance toward FAO in acidic media. Therefore, we expect this catalyst to be a better substitute for the commercial Pt/C catalyst, with an enhanced and durable performance as an anode and cathode material for direct formic acid fuel cells (DFAFCs). Moreover, the sonochemical method employed here can be easily extended to prepare other composite-based electrocatalysts for fuel cell applications. Our work demonstrates the wide potential of BN/Pd composites for promising applications.