Herein, we report an effective and simple strategy to greatly improve the photoactivity of CdO nanorods (NRs) by decorating them with CdS. The CdO–CdS heterostructured NRs grown on a FTO substrate exhibited substantially higher visible-light-driven photoactivity for a PEC cell and the degradation of methylene blue (MB) solution compared to CdO NRs.

The fabrication of a photodetector and gas sensor based on hierarchical Bi₂S₃ nanostructures is reported. Single crystalline Bi₂S₃ nanostructures with [001] growth direction were obtained via a facile hydrothermal method without any templates or surfactants. The photodetector showed steady photoresponses with a fast response time of ∼50 ms. Moreover, these Bi₂S₃ nanostructures exhibited a good sensing to methanol. These results show these hierarchical Bi₂S₃ nanostructures are promising candidates for constructing optoelectronic and gas sensing devices.

Oxygen adsorption materials play an important role in catalysis. However, the conventional catalytic mechanism of CO oxidation over copper oxide-based catalysts is based on lattice-oxygen oxidation processes, which neglects the significance of the oxidizability of the copper component and the adsorbed oxygen. Herein, we propose that poorly-crystallized CuO nanorods are capable of adsorbing abundant oxygen along with increasing the Cu oxidation states to close to 3+, meaning that CO catalytic oxidation occurs directly on the adsorbed oxygen and that Cu oxidation states do not fall to 1+ during catalytic reactions. The rate-controlled step is the surface oxidizability of the CuO nanorods, which increases with increasing temperature and oxidizability of the environment involved. These catalytic processes are distinctly different from the conventional case. The unique oxygen adsorption and catalytic properties of the CuO nanorods originate from the increasing trend in Cu oxidation state in the p-type CuO, enhanced by the defect structures and coarse surfaces of the sample. Such structure and morphology characteristics are closely related to the liquid membrane growing environment, which induces poor crystallization of the nanorods. The characterization methods include scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier transformation infrared spectroscopy (FTIR).