Hierarchical Co3O4@Ni3S2 electrode materials for energy storage and conversion.

Transition metal oxides are considered to be one of the most potential electrode materials. However, poor conductivity and insufficient active sites limit their actual applications. Rationally designed electrode materials with unique structural features can be ascribed to the efficient route for enhancing electrochemical performance. Here, we report hybrid Co3O4@Ni3S2 nanostructures obtained via a hydrothermal strategy and subsequent electrodeposition process. The obtained products can be used as electrodes for a hybrid supercapacitor with a specific capacity of 1071 C g-1 at 1 A g-1 and excellent rate capability. The as-assembled device delivers an energy density of 77.92 W h kg-1 at 2880 W kg-1. As an electrocatalyst, the above electrode possesses an overpotential of 237.6 mV at 50 mA cm-2 for oxygen evolution reaction.

Bacteria dominate the ammonia-oxidizing community in a hydrothermal vent site at the Mid-Atlantic Ridge of the South Atlantic Ocean.

Ammonia oxidation is the first and rate-limiting step of nitrification, which is carried out by two groups of microorganisms: ammonia-oxidizing bacteria (AOB) and the recently discovered ammonia-oxidizing archaea (AOA). In this study, diversity and abundance of AOB and AOA were investigated in five rock samples from a deep-sea hydrothermal vent site at the Mid-Atlantic Ridge (MAR) of the South Atlantic Ocean. Both bacterial and archaeal ammonia monooxygenase subunit A (amoA) gene sequences obtained in this study were closely related to the sequences retrieved from deep-sea environments, indicating that AOB and AOA in this hydrothermal vent site showed typical deep ocean features. AOA were more diverse but less abundant than AOB. The ratios of AOA/AOB amoA gene abundance ranged from 1/3893 to 1/242 in all investigate samples, indicating that bacteria may be the major members responding to the aerobic ammonia oxidation in this hydrothermal vent site. Furthermore, diversity and abundance of AOA and AOB were significantly correlated with the contents of total nitrogen and total sulfur in investigated samples, suggesting that these two environmental factors exert strong influences on distribution of ammonia oxidizers in deep-sea hydrothermal vent environment.