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The extensive research and developments of highly efficient oxygen electrode electrocatalysts to get rid of the kinetic barriers for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are very important in energy conversion and storage devices. Especially, exploring nonprecious metal alternatives to replace traditional noble metal catalysts with high cost and poor durability is the paramount mission. In this paper, we utilize property-flexible ZIF-67 and sulfur-functionalized graphene oxide to obtain a cobalt, nitrogen, and sulfur codoped nanomaterial with 3D hierarchical porous structures, owing to their rich dopant species and good conductivity. The crosslinked structures of polyhedron particles throughout the whole carbon framework speeds up the mass transportation and charge-delivery processes during oxygen-evolving reactions. Also, by exploring the location and coordination type of sulfur dopants, we emphasize the effects of sulfone and sulfide functional groups anchored into the graphitic structure on enhancing the catalytic abilities for ORR and OER. To note, compared to the noble metal electrocatalysts, the best-performing CoO@CoO/NSG-650 (0.79 V) is 40 mV less active than the commercial Pt/C catalyst (0.83 V) for ORR and merely 10 mV behind IrO (1.68 V) for OER. Besides, the metric between ORR and OER difference for CoO@CoO/NSG-650 to evaluate its overall electrocatalytic activity is 0.90 V, surpassing 290 and 430 mV over Pt/C (1.19 V) and IrO (1.33 V). Comprehensively, the as-prepared CoO@CoO/NSG-650 indicates excellent bifunctional catalytic activities for ORR and OER, which shows great potential for replacing noble metal catalysts in the application of fuel cells and metal-air batteries.

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Sea surface salinity (SSS) plays an important role in global water cycle. In recent years, satellite based remote sensing has proven to be a promising approach for global SSS observation. A new payload concept, named MICAP (microwave imager combined active and passive), has been introduced in this paper. MICAP is a suit of active/passive instrument package, which includes L/C/K band onedimensional MIR (microwave interferometric radiometer) and L-band DBF (digital beamforming) scatterometer, sharing a parabolic cylinder reflector. MICAP has been selected to be a candidate payload for future Chinese ocean salinity mission. In this paper, the MICAP instrument concept, specification and preliminary system design will be introduced.