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.

A highly enantioselective intramolecular arylative dearomatization of indoles via palladium-catalyzed reductive Heck reactions was developed. The new strategy led to a series of optically active indolines bearing C2-quaternary stereocenters in modest to good yields with excellent enantioselectivities (up to 99% ee).

Low‐symmetry 2D materials with unique anisotropic optical and optoelectronic characteristics have attracted a lot of interest in fundamental research and manufacturing of novel optoelectronic devices. Exploring new and low‐symmetry narrow‐bandgap 2D materials will be rewarding for the development of nanoelectronics and nano‐optoelectronics. Herein, sulfide niobium (NbS3), a novel transition metal trichalcogenide semiconductor with low‐symmetry structure, is introduced into a narrowband 2D material with strong anisotropic physical properties both experimentally and theoretically. The indirect bandgap of NbS3 with highly anisotropic band structures slowly decreases from 0.42 eV (monolayer) to 0.26 eV (bulk). Moreover, NbS3 Schottky photodetectors have excellent photoelectric performance, which enables fast photoresponse (11.6 µs), low specific noise current (4.6 × 10−25 A2 Hz−1), photoelectrical dichroic ratio (1.84) and high‐quality reflective polarization imaging (637 nm and 830 nm). A room‐temperature specific detectivity exceeding 107 Jones can be obtained at the wavelength of 3 µm. These excellent unique characteristics will make low‐symmetry narrow‐bandgap 2D materials become highly competitive candidates for future anisotropic optical investigations and mid‐infrared optoelectronic applications.

2D Bi 2 O 2 Se has shown great potential in photodetector from visible to infrared (IR) owing to its high mobility, ambient stability, and layer-tunable bandgaps. However, for the terahertz (THz) band with longer wavelength and richer spectral information, there are few reports on the research of THz detection based on 2D materials. Herein, an antenna-assisted Bi 2 O 2 Se photodetector is constructed to achieve broadband photodetection from IR to THz ranges driven by multi-mechanism of electromagnetic waves to electrical conversion. The good tradeoff between the bandgap and high mobility results in a broad spectral detection. In the IR region, the nonequilibrium carriers result from photo-induced electron-hole pairs in the Bi 2 O 2 Se body. While in the THz region, the carriers are caused by the injected electrons from the metal electrodes by the electromagnetic-induced well. The Bi 2 O 2 Se photodetector achieves a broadband responsivity of 58 A W-1 at 1550 nm, 2.7 × 10 4 V W-1 at 0.17 THz, and 1.9 × 10 8 V W-1 at 0.029 THz, respectively. Surprisingly, an ultrafast response time of 476 ns and a quite low noise equivalent power of 0.2 pW Hz-1/2 are acquired at room temperature. Our researches exhibit promising prospects of Bi 2 O 2 Se in broadband detection, THz imaging, and ultrafast sensing.

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2D layered photodetectors have been widely researched for intriguing optoelectronic properties but their application fields are limited by the bandgap. Extending the detection waveband can significantly enrich functionalities and applications of photodetectors. For example, after breaking through bandgap limitation, extrinsic Si photodetectors are used for short-wavelength infrared or even long-wavelength infrared detection. Utilizing extrinsic photoconduction to extend the detection waveband of 2D layered photodetectors is attractive and desirable. However, extrinsic photoconduction has yet not been observed in 2D layered materials. Here, extrinsic photoconduction-induced short-wavelength infrared photodetectors based on Ge-based chalcogenides are reported for the first time and the effectiveness of intrinsic point defects are demonstrated. The detection waveband of room-temperature extrinsic GeSe photodetectors with the assistance of Ge vacancies is broadened to 1.6 µm. Extrinsic GeSe photodetectors have an excellent external quantum efficiency (0.5%) at the communication band of 1.31 µm and polarization-resolved capability to subwaveband radiation. Moreover, room-temperature extrinsic GeS photodetectors with a detection waveband to the communication band of 1.55 µm further verify the versatility of intrinsic point defects. This approach provides design strategies to enrich the functionalities of 2D layered photodetectors.

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