SiO, an insulator, hardly has any photocatalytic acitivity due to its intrinsic property, and it is generally used as a hard template to increase the surface area of catalysts. However, in this work, we found that the surface state of the insulator SiO can promote the migration of photogenerated charge carriers, leading to the enhancement of the photooxidation ability of graphitic carbon nitride (g-CN). A one-pot calcination method was employed to prepare g-CN/SiO composites using melamine and SiO as precursors. The composites present considerably high photocatalytic degradation activities for 2,4-dichlorophenol (2,4-DCP) and rhodamine B (RhB) under visible light (λ > 420 nm) irradiation, which are about 1.53 and 4.18 times as high as those of bulk g-CN, respectively. The enhancement of the photocatalytic activity is due to the fact that the introduction of the insulator SiO in g-CN/SiO composites can greatly improve the specific surface area of the composites; more importantly, the impurity energy level of SiO can help accelerate the separation and transfer of electron-hole pairs of g-CN. Electron paramagnetic resonance (EPR) spectroscopy and trapping experiments with different radical scavengers show that the main active species of g-CN are superoxide radicals, while holes also play a role in photodegradation. For g-CN/SiO-5, besides superoxide radicals and holes, the effect of hydroxyl radicals was greatly improved. Finally, a possible mechanism for the photogenerated charge carrier migration of the g-CN/SiO photocatalyst was proposed.

A one-pot method for the preparation of g-C3N4/reduced graphene oxide (rGO) composite photocatalysts with controllable band structures is presented. The photocatalysts are characterized by Fouirer transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, transmission electron microscope, and Mott-Schottky analysis. The valance band (VB) of g-C3N4 exhibits a noticeable positive shift upon hybridizing with rGO, and thus results in a strong photo-oxidation ability. The g-C3N4/rGO composites show a higher photodegradation activity for 2,4-dichlorophenol (2,4-DCP) and rhodamine B (RhB) under visible light irradiation (λ ≥ 420 nm). The g-C3N4/rGO-1 sample exhibits the highest photocatalytic activity, which is 1.49 and 1.52 times higher than that of bulk g-C3N4 for 2,4-DCP and 1.52 times degradation, respectively. The enhanced photocatalytic activity for g-C3N4 originates from the improved visible light usage, enhanced electronic conductivity and photo-oxidation ability by the formed strong π-π stacking interactions with rGO.

As crystalline semiconductor nanowires are thinned down to a single-unit-cell thickness, many fascinating properties could arise pointing to promising applications in various fields. A grand challenge is to be able to controllably synthesize such ultrathin nanowires. Herein, we report a strategy, which synergizes a soft template with oriented attachment (ST-OA), to prepare high-quality single-unit-cell semiconductor nanowires (SSNWs). Using this protocol, we are able to synthesize for the first time ZnS and ZnSe nanowires (NWs) with only a single-unit-cell thickness (less than 1.0 nm) and a cluster-like absorption feature (i.e., with a sharp, strong, and significantly blue-shifted absorption peak). Particularly, the growth mechanism and the single-unit-cell structure of the as-prepared ZnS SSNWs are firmly established by both experimental observations and theoretical calculations. Thanks to falling into the extreme quantum confinement regime, these NWs are found to only absorb the light with wavelengths shorter than 280 nm (i.e., solar-blind UV absorption). Utilizing such a unique property, self-powered photoelectrochemical-type photodetectors (PEC PDs) based on the ZnS SSNWs are successfully fabricated. The PDs after interface modification with TiO2 exhibit an excellent solar-blind UV photoresponse performance, with a typical on/off ratio of 6008, a detectivity of 1.5 × 1012 Jones, and a responsivity of 33.7 mA/W. This work opens the door to synthesizing and investigating a new dimension of nanomaterials with a wide range of applications.

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