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Strain engineering can endow versatile functions, such as refining d-band center and inducing lattice mismatch, on catalysts for a specific reaction. To this end, effective strain engineering for introducing strain on the catalyst is highly sought in various catalytic applications. Herein, a facile laser ablation in liquid (LAL) strategy is adopted to synthesize gold nanoparticles (Au NPs) with rich compressive strain (Au-LAL) for electrochemical CO

Photocatalytic CO2 reduction is a promising technology to mitigate global warming and enrich energy supply. Metal–organic frameworks (MOFs) are prospective photocatalysts for CO2 reduction, but severe charge recombination and limited visible light response largely restrain their applications. As carbon dots (CDs) can act as both electron receptors and photosensitizers, here we propose to develop CD-hybridized MOF photocatalysts for improving their activity for CO2 reduction. In particular, because of the small size of CDs, we have managed to encapsulate CDs inside MOF particles and found that these CD@MOFs exhibit hugely improved photocatalytic activity compared with CD-decorated MOFs or pristine MOFs. Our investigations suggest that placing small CD cocatalysts near the internal metal–oxo clusters of MOFs can help efficient charge transfer and separation in the hybrid photocatalysts, due to the formation of many small heterojunctions among MOFs. The developed CD-hybridized MOF catalysts are characterized in detail and their working mechanism is explored. This work may demonstrate a novel strategy to develop MOF-based hybrid photocatalysts with enhanced photocatalytic activity.

Harvesting solar energy to convert carbon dioxide (CO2) into fossil fuels shows great promise to solve the current global problems of energy crisis and climate change. To achieve this goal, it is desirable to develop efficient catalysts with visible light response to cater for the solar spectrum. CdTe QDs are ideal candidates for absorbing visible light, but it is difficult to directly perform CO2 reduction due to the lack of effective catalytic sites. Herein, we report a strategy for the activation of mercaptopropionic acid (MPA)-capped CdTe QDs for visible-light-driven CO2 reduction, in which iron ions (Fe2+) are immobilized onto CdTe QDs using L-cysteine as a bridging ligand (CdTe-b-Fe). This ligand bridging strategy can immobilize Fe2+ ions on the surface of CdTe QDs as catalytic sites, and these catalytic sites can be conveniently adjusted by directly adding different types or numbers of metal ions. In addition to effectively immobilizing catalytic sites, the bridging ligands can also provide a pathway for electron transport between CdTe QDs and the catalytic sites. The CdTe-b-Fe QD system based on the ligand bridging strategy exhibits excellent catalytic properties: the yield of CH4/CO (two products together) is 126 μmol g−1 h−1, and the selectivity for carbon-based products approaches 98%. This work presents a facile strategy for immobilizing catalytic sites on QDs and provides a platform for designing efficient visible-light driven catalysts for CO2 reduction.

Photocatalytic CO2 reduction is a promising technology to mitigate global warming and enrich energy supply. Metal-organic frameworks (MOFs) are prospective photocatalysts for CO2 reduction, but severe charge recombination and limited visible light response largely restrain their applications. As carbon dots (CDs) can act as both electron receptors and photosensitizers, here we propose to develop CD-hybridized MOF photocatalysts for improving their activity for CO2 reduction. In particular, because of the small size of CDs, we have managed to encapsulate CDs inside MOF particles and found that these CD@MOFs exhibit hugely improved photocatalytic activity compared with CD-decorated MOFs or pristine MOFs. Our investigations suggest that placing small CD cocatalysts near the internal metal-oxo clusters of MOFs can help efficient charge transfer and separation in the hybrid photocatalysts, due to the formation of many small heterojunctions among MOFs. The developed CD-hybridized MOF catalysts are characterized in detail and their working mechanism is explored. This work may demonstrate a novel strategy to develop MOF-based hybrid photocatalysts with enhanced photocatalytic activity.

Harvesting solar energy to convert carbon dioxide (CO

The combination of upconversion nanocrystals with a wide-bandgap semiconductor is an efficient strategy to develop near-infrared (NIR)-responsive photocatalysts. The photocatalytic activity of the hybrid structures is greatly determined by the efficiency of the energy transfer on the interface between upconversion nanocrystals and the semiconductor. In this work, we demonstrate the interface design of a NaYF4:Yb,Tm–BiOCl hybrid structure based on the choice of suitable BiOCl facets in depositing NaYF4:Yb,Tm upconversion nanocrystals. It was found that the selective deposition of NaYF4:Yb,Tm nanocrystals on the BiOCl(110) facet can greatly enhance the photocatalytic performance in dye degradation compared with the sample with NaYF4:Yb,Tm nanocrystals loaded on the BiOCl(001) facet. Two effects were believed to contribute to this enhancement: (1) a stronger UV emission absorption ability of the BiOCl(110) facet from NaYF4:Yb,Tm in generating more photo-induced charge carriers resulted from the narrower bandgap; (2) a shorter diffusion distance of photogenerated charge carriers to the BiOCl(110) reactive facet for surface catalytic reactions owing to the spatial charge separation between different facets. This work highlights the rational interfacial design of an upconversion nanocrystal–semiconductor hybrid structure for enhanced energy transfer in photocatalysis.

High-quality hexagonal NaYF4:Yb,Tm upconversion nanocrystals (UCNs) prepared in organic solutions display uniform sizes and strong UC emissions, but they possess a hydrophobic surface which hinders combining them with various semiconductor nanocrystals (NCs) to form a hybrid NIR-activated photocatalyst. Herein we present a facile approach to modify hydrophobic UCNs with a uniform carbon layer and enable them with hydrophilicity and surface functionalization. The carbon shell provides a good substrate for enriching with metal ions and in situ generation of CdS nanoclusters on the particle surface which can utilize both the upconverted UV and visible emissions. The developed NaYF4:Yb,Tm@C@CdS nanoparticles are characterized with TEM, SEM, XRD, PL and UV-Vis spectra and their formation mechanism is elucidated. The products display good photocatalytic activity under visible light and obviously enhanced performance under Vis-NIR light, due to the efficient utilization of UC emissions and the strong adsorption capacity of the carbon shell. The working mechanism of the hybrid photocatalysts is also proposed.

The combination of upconversion nanocrystals with a wide-bandgap semiconductor is an efficient strategy to develop near-infrared (NIR)-responsive photocatalysts. The photocatalytic activity of the hybrid structures is greatly determined by the efficiency of the energy transfer on the interface between upconversion nanocrystals and the semiconductor. In this work, we demonstrate the interface design of a NaYF

A facile method has been developed to synthesize uniform nanoscale YF3 architectures. Interestingly, the unique YF3 nanostructure exhibits a flat and rhombic appearance which is formulated through the hierarchical assembly of YF3 nanocrystals along a specific crystalline orientation. Investigations on the formation process suggest that an assembly disassembly process is responsible for the construction of this novel structure. Enabled by doping with different lanthanides ions, the products can exhibit various down- or up-conversion luminescences, showing their potentials in serving as versatile host matrixes. The tunable luminescent properties allow designing effective upconversion photocatalysts when the doped YF3 nanostructures are coated with a TiO2 shell on their surface. In particular, the YF3@TiO2 hybrid structures have the porous nature that is partially inherited from the YF3 architectures, whose high surface-to-volume ratio facilitates their use as photocatalysts. In this article, we have demonstrated that the YF3:Yb,Tm@TiO2 structures exhibit satisfactory photocatalytic activities under the irradiation of both UV and near IR light. As compared with the conventional TiO2 catalysts, the hybrid structures here offer better performance in photocatalysis in the full solar spectrum. It is anticipated that this work provides a new approach to designing photocatalysts with responses to a broader spectral range.

A facile method has been developed to synthesize uniform nanoscale YF3 architectures. Interestingly, the unique YF3 nanostructure exhibits a flat and rhombic appearance which is formulated through the hierarchical assembly of YF3 nanocrystals along a specific crystalline orientation. Investigations on the formation process suggest that an assembly disassembly process is responsible for the construction of this novel structure. Enabled by doping with different lanthanides ions, the products can exhibit various down- or up-conversion luminescences, showing their potentials in serving as versatile host matrixes. The tunable luminescent properties allow designing effective upconversion photocatalysts when the doped YF3 nanostructures are coated with a TiO2 shell on their surface. In particular, the YF3@TiO2 hybrid structures have the porous nature that is partially inherited from the YF3 architectures, whose high surface-to-volume ratio facilitates their use as photocatalysts. In this article, we have demonstrated that the YF3:Yb,Tm@TiO2 structures exhibit satisfactory photocatalytic activities under the irradiation of both UV and near IR light. As compared with the conventional TiO2 catalysts, the hybrid structures here offer better performance in photocatalysis in the full solar spectrum. It is anticipated that this work provides a new approach to designing photocatalysts with responses to a broader spectral range.