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Abstract The violation of strong cosmic censorship (SCC) in RNdS black holes by a minimally coupled neutral massless scalar field has recently been discovered. This paper investigates the stability of the Cauchy horizon of a spherically charged de-Sitter black hole surrounded by dark matter under perturbations from a massless scalar field. Our results show that SCC can also be destroyed in the nearly extremal region, regardless of the presence of dark matter. However, the existence of dark matter can mitigate the extent of SCC violation, particularly when the cosmological constant and dark matter energy density are both small. Notably, the violation region of SCC as a function of the dark matter state parameter does not exhibit a simple monotonic decrease, suggesting that the influence of dark matter on SCC is not straightforward and may be complex.

The photocatalytic reduction of CO2 to chemical fuels is attractive for addressing both the greenhouse effect and the energy crisis, but the key challenge is the design and synthesis of photocatalysts with remarkable performance under visible-light irradiation. Herein, we present two novel polyoxometalate-based organo–metallophosphate frameworks (POMPOs), formulated as [Zn4(PO4)(C7H8N4)6][BW12O40]·2H2O (1) and [Co4(PO4)(C7H8N4)6][BW12O40]·1.5H2O (2). According to the single crystal analysis, both compounds possess host organo–metallophosphate (OMPO) frameworks constructed with PO43− anions, with the Keggin-type polyoxometalate H5BW12O40 (BW12) as a guest encapsulated in these size-matched frameworks. Due to the synergistic combination of the POMs and OMPO frameworks in the system of photocatalytic CO2 reduction, compound 2 could act as a highly efficient cocatalyst in combination with the [Ru(bpy)3]Cl2 complex. The CO generation rate over compound 2 is 10 852 μmol g−1 h−1 with a high selectivity of 93.4%, which is superior to that of most reported POM-based or MOF-based catalysts for CO2 photoreduction. To our knowledge, this is the first report of OMPO frameworks functionally combined with Keggin-type POMs being extended for the photoreduction of CO2 and this affords a new pathway for the efficient photoconversion of CO2 to CO. [ABSTRACT FROM AUTHOR]