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The development of eco-friendly and low cost catalysts is challenging. Here, heterostructures of Bi 2 S 3 quantum dots (QDs) doped onto ultrathin BiOCl nanosheets were synthesized by a facile hydrothermal method to exploit efficient photosensitizers with appropriate electronic states to enhance the transfer of electrons. The obtained Bi 2 S 3 À BiOCl showed highly efficient photocatalytic ability for selective oxidation of aromatic alcohols to aldehydes. More oxygen vacancies are formed on the exposed 001 facet of the ultrathin BiOCl, which can effectively trap electrons and form * O 2 À radicals. The cooperation between the BiOCl and the Bi 2 S 3 QDs effectively separates photogener-ated electron-hole pairs at the heterointerface and facilitates the cooperative actions of * O 2 À radicals and holes, which brings about a desirable photocatalytic efficiency for the selective oxidation of aromatic alcohols. This work highlights the synergistic effect of semiconductor QDs and two-dimensional materials on selective conversion processes and provides a new design paradigm using noble metal-free heteromaterials with high photocatalytic activity. This opens new possibilities for photocatalyst design using heteromaterials with high photocatalytic activity.

PurposeThe purpose of this paper is to obtain risk indicators of water security of drought periods in which the indices of reliability, resiliency, and vulnerability are integrated.Design/methodology/approachIt is not reasonable that weight coefficients of different risk indices are often determined subjectively in conventional procedures, so the entropy weight method is introduced and chosen to solve the problem. Entropy weight method can get the weight coefficients of different risk indices objectively and is valid from the case study.FindingsThe feasibility and validity of entropy weight methods to determine weight coefficients of different risk indices objectively are recognized.Research limitations/implicationsAccessibility and availability of data are the main limitations.Practical implicationsThe paper provides a more objective risk indicator of water security of drought periods for water resources managers.Originality/valueThis paper determines the weight coefficients of different risk indices for risk assessment of water security of drought periods based on hazard entropy. The paper is aimed at water resources managers and relative researchers, especially those who deal with risk assessment of water security of drought periods.

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