While the carbon-based metal-free electrocatalysts for oxygen reduction reaction (ORR) have experienced great progress in recent years, the fundamental issue on the origin of ORR activity is yet far from being clarified. To date, the ORR activities of these electrocatalysts are usually attributed to different dopants, while the contribution of intrinsic carbon defects has been little touched. Herein, we report the high ORR activity of the defective carbon nanocages, which is better than that of the B-doped carbon nanotubes and comparable to that of the N-doped carbon nanostructures. Density functional theory (DFT) calculations indicate that pentagon and zigzag edge defects are responsible for the high ORR activity. The mutually corroborated experimental and theoretical results reveal the significant contribution of the intrinsic carbon defects to ORR activity, which is crucial for understanding the ORR origin and exploring the advanced carbon-based metal-free electrocatalysts.

3D few-layer graphene-like carbon with hierarchical open porous architecture is obtained by a new in situ Cu template method, leading to top-level supercapacitive performance, especially state-of-the-art power density. An effective new approach is demonstrated, which can extend the understanding of structure-performance relationships for many electrochemical energy-storage systems and form a significant complement to classical electrochemical impedance spectroscopy.

High volumetric energy density combined with high power density is highly desired for electrical double-layer capacitors. Usually the volumetric performance is improved by compressing carbon material to increase density but at the much expense of power density due to the deviation of the compressed porous structure from the ideal one. Herein the authors report an efficient approach to increase the density and optimize the porous structure by collapsing the carbon nanocages via capillarity. Three samples with decreasing sizes of meso- and macropores provide us an ideal model system to demonstrate the correlation of volumetric performance with porous structure. The results indicate that reducing the surplus macropores and, more importantly, the surplus mesopores is an efficient strategy to enhance the volumetric energy density while keeping the high power density. The optimized sample achieves a record-high stack volumetric energy density of 73 Wh L in ionic liquid with superb power density and cycling stability.

Direct ethanol fuel cells are attractive alternative power sources due to the use of liquid fuels featuring high energy density, low toxicity, easy storage, and biomass-derived production. To date, most Pt-based electrocatalysts are still limited by low mass activity and high susceptibility to poisoning for the ethanol oxidation reaction (EOR) in acidic medium. Herein, we have constructed a ternary platinum/tin oxide/nitrogen-doped carbon electrocatalyst for the EOR by highly dispersing the hybridized platinum/tin oxide on nitrogen-doped carbon nanocages. CO electrooxidation from the stripping experiments is used as a sensitive indicator to evaluate the antipoisoning capability of the catalysts. By a comparison study on a series of designed catalysts, the correlation of the CO resistibility with the geometrical configuration has been well established for the catalysts. We demonstrate that the efficient ternary synergism of Pt/SnO x /N-doped sp2-C via the heterointerfaces is the key to high CO resistibility, which could facilitate the oxidative removal of CO species at Pt sites by the adsorbed OH species generated at neighboring SnO x sites and thereby the facile regeneration of Pt active sites. Accordingly, a synergistic catalyst has been optimized which shows high EOR performance in acidic medium with a mass activity of 1187 mA mgPt –1 and high durability, in comparison with most reported catalysts to date. This study provides an approach of exploring advanced EOR electrocatalysts for potential applications.

An iron carbonyl-mediated Ostwald-ripening-like growth mechanism of an FexCy active phase in Fischer–Tropsch synthesis is firstly revealed by in situ mass-spectrometric and theoretical analysis.