Exploring highly efficient heterostructured photocatalysts for converting CO2 to value-added chemicals has long been pursued, which is mainly limited by inefficient visible/near-infrared (NIR) photon capture, undesirable electron-hole recombination, and insufficient...
This paper aims to study the electrical parameters (electrical resistivity and alternating current (AC) impedance spectroscopy) of cement paste with rice husk ash (RHA). The water to cement (Mass ratio of water to cement (w/c)) ratios of the paste in this study varied from 0.4 to 0.5. The mass ratio of rice husk ash in each w/c ratio of specimens ranged from 0% to 15% by t mass of cement. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to determine the microstructures of specimens. Moreover, the slump flow and plastic viscosity of fresh paste were determined. The results indicated that with the increasing dosage of RHA, the fluidity decreased, while the plastic viscosity increased. Meanwhile, a high w/c ratio led to a low plastic viscosity and high slump flow. The electrical resistivity of RHA cement paste gradually ascended with the increasing curing period. The conduction of specimens intricately changed by mixing RHA, a reasonable equivalent circuit was selected to describe the conduction mechanism by AC impedance spectroscopy. Additionally, the results of XRD and SEM showed that RHA could effectively promote the hydration process as well as decrease the size and number of cracks in hardened cement paste.
Coupling hollow semiconductor with metal–organic frameworks (MOFs) holds great promise for constructing high‐efficient CO2 photoreduction systems. However, energy band mismatch between them makes it difficult to exert their advantages to maximize the overall photocatalytic efficiency, since that the blockage of desirable interfacial charge transfer gives rise to the enrichment of photoelectrons and CO2 molecules on the different locations. Herein, an interfacial engineering is presented to overcome this impediment, based on the insertion of plasmonic metal into the heterointerfaces between them, forming a stacked semiconductor/metal@MOF photocatalyst. Experimental observations and theoretical simulations validate the critical roles of embedded Au in maneuvering the charge separation/transfer and surface reaction: (i) bridges the photoelectron transfer from hollow CdS (H‐CdS) to ZIF‐8; (ii) produces hot electrons and shifts them to ZIF‐8; (iii) induces the formation of ZIF‐8 defects in promoting the CO2 adsorption/activation and transformation to CO with low energy barriers. Consequently, the as‐prepared H‐CdS/Au@ZIF‐8 with optimal ZIF‐8 thickness exhibits distinctly boosted activity and superb selectivity in CO production as compared with H‐CdS@ZIF‐8 and other counterparts. This work provides protocols to take full advantages of components involved for enhanced solar‐to‐chemical energy conversion efficiency of hybrid artificial photosynthetic systems through rationally harnessing the charge transfer between them.
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