It is a critical challenge to construct efficient precious-metal-free bifunctional oxygen electrocatalysts for fuel cell and metal-air batteries via structural and component engineering. Herein, a one-dimensional mesoporous double-layered tubular structure, where CoS nanocrystals are incorporated into nitrogen, sulfur codoped carbon, is successfully synthesized via the coordinated-assisted polymerization and sacrificial template methods. The double-layered tubular structure provides for a large electrochemically active surface area and promotes fast mass transfer. Cobalt oxides/oxyhydroxides, which are evolved from the sulfides during the catalytic processes, as the main active sites efficiently catalyze the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), in cooperation with the Co-N-C and heteroatom-induced active sites. Hence, it demonstrates excellent bifunctional electrocatalytic activity with the overvoltage between the OER potential at 10 mA cm ( E) and ORR half-wave potential ( E) of 0.707 V, which is superior to most of precious-metal-free bifunctional oxygen electrocatalysts reported recently, as well as the state-of-art Pt/C and RuO catalysts.

The catalytic performance of supported heterogeneous catalysts is mainly dependent on their constitutive components including active species and supports. Therefore, the design and development of effective catalysts with synergistic enhanced effect between active sites and supports is of great significance. A facile in situ reduction approach to prepare amine-functionalized silica nanotubes (ASNTs)-supported Pd (ASNTs@Pd) composite catalyst is demonstrated in this article. Benefiting from the intrinsic physical and chemical properties of the ASNTs support and deposited Pd nanoparticles (NPs), the as-prepared ASNTs@Pd catalyst exhibits superior catalytic activity, stability, and reusability toward nitroarene reduction reactions. For catalytic reduction of 4-nitrophenol, the turnover frequency (TOF) is as high as 313.5 min–1, which is much higher than that of commercial Pd/C (5.0 wt %) and many noble-metal based catalysts reported in the last 5 years. In addition, a high TOF of 57.4 min–1 was also realized by ASNTs@Pd catalyst for the Suzuki coupling reaction.

Oxygen molecules are efficiently reduced under the catalysis of raisin bread-like Fe1−xS/N, S-MGCS electrocatalysts via a dominant 4e− process.

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