A highly shape selective synthesis of Cu and Cu@Cu-Ni nanocubes and nanowires has been developed by modulating the coordination chemistry of transition metal ions with a trioctylphosphine (TOP)-Cl(-) ligand pair in oleylamine under mild organic solvent conditions. The as-prepared nanocubes have a face-centered cubic (fcc) phase and are covered by six {100} facets, whereas the as-prepared nanowires have a multi-twinned structure and grow along the [110] direction. Both the Ni(2+) and Cl(-) ions, along with TOP, play vital roles in determining the final morphology of the as-prepared nanocrystals (NCs). TOP can be used to selectively generate single-crystal seeds at the initial stage, which then grow into nanocubes in the presence of Cl(-) ions, while the absence of TOP leads to the formation of multi-twined crystal seeds that finally develop into nanowires. Moreover, Ni can be incorporated to form a Cu-Ni alloy shell over a Cu core at higher temperatures in a one-pot process, which makes diamagnetic Cu NCs magnetically responsive and has a significant influence on their optical properties.

Hydroxyl-rich g-C 3 N 4 nanosheets were prepared by ultrasonic exfoliation of bulk g-C 3 N 4 in water. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, UV-vis absorption spectroscopy, photoluminescence spectroscopy, time-resolved fluorescence decay spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and photocurrent response. The results indicated that the bulk g-C 3 N 4 was exfoliated to five or six layers. The specific surface area increased from 8.66 m 2 g À1 for the bulk g-C 3 N 4 to 26.48 m 2 g À1 for the nanosheets. More importantly, the amount of hydroxyl group on the g-C 3 N 4 surface increased greatly upon ultrasonic treatment in water. Meanwhile, the separation rate of charge carriers was improved greatly and the conduction band potential shifts to a more negative value. All these can explain the enhanced activity of g-C 3 N 4 nanosheets for visible-light photocatalytic reduction of CO 2 .

Nano-heterostructures are widely used in the field of optoelectronic devices, and an optimal proportion usually exists between the constituents that make up the structures. Investigation on the mechanism underlying the optimal ratio is instructive for fabricating nano-heterostructures with high efficiency. In this work, BiOCl/BiS type-II nano-heterostructures with different BiS/BiOCl ratios have been prepared via epitaxial growth of BiS nanorods on BiOCl nanosheets with solvothermal treatment at different sulfuration temperatures (110-180 °C) and their photoelectrochemical (PEC) performances as photoanodes have been studied. Results indicate that the BiS content increases with the sulfuration temperature. BiOCl/BiS-170 (i.e., sulfurized@170 °C) exhibits the highest PEC performance under visible-light illumination, whereas BiOCl/BiS-180 with the maximum BiS content shows the highest visible-light absorption, i.e., possessing the best potential for charge generation. Further analysis indicates that the BiOCl/BiS heterojunction interface is also crucial in determining the PEC performance of the obtained heterostructures by influencing the charge separation process. With increasing BiS content, the interface area in the BiOCl/BiS nano-heterostructures increases first and then decreases due to the mechanical fragility of the nanosheet-nanorod structure and the structural instability in the [010] direction of BiS with higher BiS content. Therefore, the increasing content of the BiS does not necessarily correspond to higher heterojunction area. The optimal performance of BiOCl/BiS-170 results from the maximum of the synthetic coordination of the charge generation and separation. This is the first time ever to figure out the detailed explanation of the optimal property in the nano-heterostructures. The result is inspiring in designing high-performance nano-heterostructures from the point of synthesizing morphological mechanically robust heterostructure and structurally stable constituents to reach a high interfacial area, as well as high light-absorption ability.

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BiOCl nanosheets with different percentages of exposed {001} facets were prepared via mild hydrolysis by a controlled facile hot injection technique, which exhibited relatively high activity for photocatalytic reduction of CO2 to CH4.