Search

Copper-oxo clusters have been of great interest due to their fascinating structures and potential applications. However, it was difficult to construct copper clusters using conjugated macromolecules by a conventional solvent method due to their insolubility. Herein, a hydroxo-bridged [Cu20] cluster was self-assembled through the employment of solvothermal techniques by using the conjugated macromolecule anthracene-9-carboxylic acid and copper bromide or cuprous bromide. The bromine anion as a template has been found to play a crucial role in the synthesis of the [Cu20] cluster compared to other anion-based copper salts, which form the paddlewheel [Cu2] cluster. The catalytic tests showed that the [Cu20] cluster exhibited an excellent conversion efficiency in the cycloaddition reaction of CO2 with epichlorohydrin. The turnover number (TON) was about 58 823, while the turnover frequency (TOF) was approximately 19 607 h−1. As far as we know, these values in this work for metal–organic catalysts were the highest among the previously reported catalytic data on the cycloaddition of CO2 to epoxide under similar conditions. The cycling test showed that the catalytic activity of the [Cu20] cluster in the cycloaddition of CO2 to epoxide was retained for five repeated cycles, indicating that the catalytic reaction was actually heterogeneous. The high catalytic efficiency and stability enable the use of raw power station flue gas, which reveals the broad prospect of this copper-oxo cluster in the industrial application of CO2 fixation. [ABSTRACT FROM AUTHOR]

The design and construction of wide-bandgap semiconductor nanostructures is a promising way to achieve photocatalytic overall water-splitting, because their redox potentials easily simultaneously satisfy the thermodynamic requirements of water reduction and oxidation. However, the narrow light-harvesting range and the fast charge recombination of wide-bandgap semiconductors tremendously limit their photocatalytic activities. Herein, we developed a novel wide-bandgap semiconductor photocatalyst of CaNb2O6 nanofibers (NFs) fabricated by an electrospinning technique, followed by calcination. Upon UV-visible light irradiation, the as-electrospun CaNb2O6 NFs could split water into H2 and O2 without adding any cocatalyst and sacrificial agent. The H2-production rate of CaNb2O6 NFs was ∼7.7 times higher than that of CaNb2O6 nanoparticles (NPs). It is because the CaNb2O6 NFs with the NP-packed 1D nanostructure possess abundant homogeneous interfaces to facilitate inter-particle continuous charge migration, thereby prolonging the lifetimes of photoinduced electrons and holes toward both water reduction and oxidation. Notably, the introduction of Au NPs into the CaNb2O6 NFs could extend light absorption from the UV to the visible light range. The optimal sample of 1.0 at% Au NP-decorated CaNb2O6 NFs exhibited ∼13.1-fold enhancement of photocatalytic activity for overall water splitting as compared to CaNb2O6 NFs. This remarkable enhancement is attributed to an interesting plasmonic sensitization process, during which the visible-light-excited hot electrons in plasmonic Au NPs are able to transfer to the interband-excited CaNb2O6 across their hetero-interface for enhancing the photocatalytic water reduction. Meanwhile, the hot holes left in the Au NPs possess a longer lifetime for fulfilling the photocatalytic water oxidation. [ABSTRACT FROM AUTHOR]

Herein, an interesting electron-donating strategy is proposed to guide the construction of novel CdS-based MOFs for co-catalyst-free photocatalytic H2 evolution in the presence of triethanolamine as the hole-scavenger. The optimally designed CdS-based MOF exhibits an exceptional H2-evolution rate of 26.1 mmol g−1 h−1 which is almost the highest rate among the reported co-catalyst-free MOF systems. [ABSTRACT FROM AUTHOR]

Abstract: Plasmonic metal nanostructures have been widely used to enhance the upconversion efficiency of the near‐infrared (NIR) photons into the visible region via the localized surface plasmon resonance (LSPR) effect. However, the direct utilization of low‐cost nonmetallic semiconductors to both concentrate and transfer the NIR‐plasmonic energy in the upconversion system remains a significant challenge. Here, a fascinating process of NIR‐plasmonic energy upconversion in Yb3+/Er3+‐doped NaYF4 nanoparticles (NaYF4:Yb‐Er NPs)/W18O49 nanowires (NWs) heterostructures, which can selectively enhance the upconversion luminescence by two orders of magnitude, is demonstrated. Combined with theoretical calculations, it is proposed that the NIR‐excited LSPR of W18O49 NWs is the primary reason for the enhanced upconversion luminescence of NaYF4:Yb‐Er NPs. Meanwhile, this plasmon‐enhanced upconversion luminescence can be partly absorbed by the W18O49 NWs to re‐excite its higher energy LSPR, thus leading to the selective enhancement of upconversion luminescence for the NaYF4:Yb‐Er/W18O49 heterostructures. More importantly, based on this process of plasmonic energy transfer, an NIR‐driven catalyst of NaYF4:Yb‐Er NPs@W18O49 NWs quasi‐core/shell heterostructure, which exhibits a ≈35‐fold increase in the catalytic H2 evolution from ammonia borane (BH3NH3) is designed and synthesized. This work provides insight on the development of nonmetallic plasmon‐sensitized optical materials that can potentially be applied in photocatalysis, optoelectronic, and photovoltaic devices. [ABSTRACT FROM AUTHOR]