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The gradual depletion of global fossil energy and environmental pollution make the development of hydrogen energy imminent. Two-dimensional g-C3N4 (CN) based heterostructures have attracted considerable research interest in photocatalytic H2...

Herein, a new photocatalyst PdS@UiOS@CZS is successfully synthesized, where thiol-functionalized UiO-66 (UiOS), a metal−organic framework (MOF) material, is used as a host to encapsulate PdS quantum dots (QDs) in its cages, and Cd 0.5 Zn 0.5 S (CZS) solid solution nanoparticles (NPs) are anchored on its outer surface. The resultant PdS@UiOS@CZS with an optimal ratio between components displays an excellent photocatalytic H 2 evolution rate of 46.1 mmol h −1 g −1 under visible light irradiation (420∼780 nm), which is 512.0, 9.2, and 5.9 times that of pure UiOS, CZS, and UiOS@CZS, respectively. The reason for the significantly enhanced performance is that the encapsulated PdS QDs strongly attract the photogenerated holes into the pores of UiOS, while the photogenerated electrons are effectively migrated to CZS due to the heterojunction effect, thereby effectively suppressing the recombination of charge carriers for further high-efficiency hydrogen production. This work provides an idea for developing efficient photocatalysts induced by hole attraction.

NO x emission is a major environmental issue, and selective catalytic reduction (SCR) is the most effective method for the conversion of NO x to harmless N2 and H2O. Manganese oxide has excellent low-temperature (LT) denitration (de-NO x ) activity, but poor SO2 tolerance hinders its application. Herein, we report an interesting SCR catalyst, quasi-metal–organic-framework (MOF) nanorod containing manganese (quasi-Mn-BTC) with abundant oxygen vacancies (Vo), unique hierarchical porous structure, and half-metallic property, which successfully overcome the disadvantage of poor SO2 tolerance of Mn-based catalysts. The NO x conversion over the Mn-BTC-335 °C only drops by 7% until SO2 is gradually increased to 200 ppm from 100 ppm for 36 h. Furthermore, the quasi-Mn-BTC presents excellent LT de-NO x performance with above 90% NO x conversion between 120 and 330 °C at a gas hourly space velocity of 36,000 h–1. Experimental and theoretical calculations confirm that the difficult electron transport between SO2 and active sites can prevent it from competing adsorption with NH3 and NO. Furthermore, the low degree of d–p hybridization and unstable p–p hybridization of SO2 on the active sites make it difficult for adsorption and oxidation; thus, the weak adsorption of SO2 can prevent it from sulfation on the active sites, ensuring Mn-BTC-335 °C excellent SO2 tolerance. Additionally, the half-metallicity property, the extraordinary d–sp hybridization, and the high degree of s–p hybridization cause strong bonding and the delocalization of electrons that promote the charge transfer and adsorbed ion diffusion for NH3 and NO adsorption, promoting the LT de-NO x performance. In situ diffuse reflectance infrared Fourier transform spectra and density functional theory calculation further reveal that the de-NO x reaction over Mn-BTC-335 °C follows both Eley–Rideal (E-R) and Langmuir–Hinshelwood (L-H) mechanisms. The “standard reaction” is more likely to occur in the E-R reaction, while the “fast reaction” is prone to occur in the L-H pathway, and HNNOH and NH3NO2 are the two key intermediates. This work provides a viable strategy for augmenting the LT de-NO x and SO2 tolerance of Mn-based catalysts, which may pave a new way in the application of MOFs in de-NO x , and the complete reaction mechanism provides a solid basis for future improvements of the LT NH3-SCR de-NO x reaction.

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