Due to a large surface-to-volume ratio, the optoelectronic performance of lowdimensional semiconductor nanostructure-based photodetectors depends in principle on chemisorption/photodesorption at the exposed surface, but practical examples that show such an effect are still unavailable. Some theoretical calculations have predicted that the {001} facets of In₂O₃ can effectively accumulate photogenerated holes under irradiation, providing a model material to examine whether the facet cutting of nanowires (NWs) can boost their optoelectronic performance. Herein, we present the design and construction of a novel nanowire-based photodetector using square In₂O₃ NWs with four exposed {001} crystal facets. The photodetector delivers excellent optoelectronic performance with excellent repeatability, fast response speed, high spectral responsivity (R_λ), and high external quantum efficiency (EQE). The R_λ and EQE values are as high as 4.8 × 10⁶ A/W and 1.46 × 10⁹%, respectively, which are larger than those of other popular semiconductor photodetectors. In addition, the square In₂O₃ NWs show hydrophobic wettability as manifested by a contact angle of 118° and a fast photoinduced reversible switching behavior is observed.

Carbon nitrides synthesized by thermal polycondensation of melamine at 700 ℃ exhibit photoluminescence (PL) ranging from 400 to 650 nm. This broad PL is attributed to band to band transitions and bandtail transitions of lone pair (LP) states of intra-tri-s-triazine and inter-tri-s-triazine nitrogens. The proposed PL mechanism is further confirmed by diffusion reflectance spectroscopy, as well as time-resolved and temperature-dependent PL. This intense fluorescence is stable at different pH and resistant to UV exposure, suggesting that this inexpensive broadband luminescent material could be significant for whitelight-emitting (WLE) applications. Thus, quasi-WLE films and membranes with designed patterns are fabricated by embedding the carbon nitrides into polymethyl methacrylate. Moreover, even broader PL (400 to 740 nm) is acquired in composite films composed of carbon nitrides, further suggesting that the carbon nitrides are robust candidates for WLE.