A series of NbO x /Ce 0.75 Zr 0.25 O 2 catalysts for the selective catalytic reduction of NO with ammonia (NH 3-SCR) were synthesized using a wetness impregnation method. The effect of niobia loading was studied in relation to the active sites and surface acidity. NH 3 /NO oxidation, X-ray diffraction, Infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, H 2 temperature-programmed reduction, O 2 /NH 3 temperature-programmed desorption, and diffuse reflectance infrared Fourier transformed spectroscopy experiments were performed to correlate the catalyst structure and surface properties to catalytic performance after Nb 2 O 5 modification. The catalyst with 15 wt.% Nb 2 O 5 loading showed high NH 3-SCR activity and nearly 100% N 2 selectivity within a broad operation temperature window (190-460 °C) at a high space velocity (300, 000 h −1). On this catalyst, Nb n+ was mainly distributed in the form of typical monomeric and polymeric NbO x species, and was partially incorporated into the Ce 0.75 Zr 0.25 O 2 lattice at the Nb n+-O-Ce n+ (Zr n+) interface. The electron redistribution effect arising from the occupation of cerium sites by Nb n+ ions promoted the formation of Ce 3+ ions, oxygen vacancies and active oxygen species. This interaction was closely associated with the distribution of NbO x species which varied with niobia loading. NbO x themselves were acid sites and by attracting electrons they enhanced Lewis acid sites on CZ surface, which promoted the adsorption of NH 3 and inhibited the unselective oxidation of NH 3 to NO x. The increased amounts of active oxygen species over NbCZ catalysts promoted the adsorptive oxidation of NH 3 to NH 2 and NO to NO 3 at low temperatures, and thus facilitated the reaction of ads-NH 3 and ads-NO 3-/NO 2 species. This effect as well as the increased amount of acid sites led to good NH 3-SCR performance of Nb15CZ in a wide temperature range.

Ship draft measurement is of great significance for ensuring navigation safety and facilitating ship control. In this work, a self-powered water level sensor based on a liquid-solid tubular triboelectric nanogenerator (LST-TENG) is proposed and analyzed. The LST-TENG is made of multiple copper electrodes uniformly distributed along a polytetrafluoroethylene (PTFE) tube. When water flows into the PTFE tube, it induces alternating flows of electrons between the main electrode and the distributed bottom electrodes. The obvious peaks in the derivative of open-circuit voltage with respect to time are found to correspond with the electrode distribution. Then it can be utilized as a robust and sensitive indicator for detecting the water level as the number of obvious peaks in the derivative of open-circuit voltage is directly related to the water level height. The ship draft is successfully detected using the LST-TENG with an accuracy of 10 mm. It shows that the water level sensor has stable performance for liquid-solid interface monitoring. Therefore, this LST-TENG is selfpowered, robust, and accurate for extensive applications in marine industry.

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