During the photocatalytic CO2 conversion process, fast charge transport, abundant active sites, and high visible light utilization in photocatalysts are key to achieving excellent CO2 conversion efficiency. In this work, hierarchical CuS@SnS2 p-n heterostructure hollow cubes were designed and prepared for photocatalytic CO2 reduction by fabricating CuS hollow cubes via the partial sulfidation and etching using Cu2O cubes as precursor and the final growing SnS2 nanosheets on the CuS hollow cubes. The prepared CuS@SnS2 p-n heterostructure hollow cubes showed an improved efficiency of photocatalytic CO2 reduction compared with the bare CuS and SnS2 control samples. The p-n heterojunction formed between SnS2 and CuS as well as its hollow structure enhanced the charge carrier separation and the light absorption capacity of the hybrid catalyst. Furthermore, after anchoring Au nanoparticles (NPs), the Schottky junction was constructed, and Au NPs serve as photoelectron reservoirs, triggering the aggregation of photoinduced electrons on the surface for CO2 photoreduction. The strong interaction between bimetallic sulfide support and Au NPs was found to be conducive to binding and reducing CO2 molecules. The localized surface plasmon resonance effect of Au NPs also improves the light harvesting ability of photocatalysts. Thus, the cooperative effects of these positive effects greatly facilitated photocatalytic CO2 reduction, and the optimized composite photocatalyst exhibited CO and CH4 yields of 346.3 and 208.5 μmol g-1 h-1, respectively. This work presents an efficient design of high-performance catalysts for photocatalytic CO2 reduction.
Fabricating photocatalysts with customizable structure and composition using different metal-organic framework (MOF) building blocks has intriguing implications in chemistry and materials science, but it is challenging to do so. This work developed hierarchical MIL-125(Ti)@TiO2\Co3S4 ternary hybrid photocatalysts with hollow nanodisk structure for photocatalytic CO2 reduction. The creation of MIL-125(Ti) nanodiscs was the first step in the synthesis. Next, Co-based zeolite imidazolium ester backbone (ZIF-67) nanolayer was encapsulated on the MIL-125(Ti) nanodisks to form core@shell MIL-125(Ti)@ZIF-67 nanodisks. The following sulfidation process under solvothermal condition leads to the production of hierarchical MIL-125(Ti)@TiO2\Co3S4 hollow nanodisks. Along with offering a huge number of active sites, this hollow nanodisk structure ternary hybrid significantly enhances charge mobility and visible light absorption. Considering the advantages listed above, the CO2 photoreduction activity of the optimized hierarchical MIL-125(Ti)@TiO2\Co3S4 hollow nanodisk catalyst was significantly increased when compared to single-component catalysts (MIL-125(Ti), TiO2, and Co3S4) and binary hybrid catalysts (MIL-125(Ti)@TiO2 and TiO2\Co3S4) under simulated sunlight irradiation. CO is the main product with a productivity of 587.50 μmolg-1h-1, which is almost seven times higher than that of pure MIL-125(Ti). The potential photocatalytic mechanism of the ternary hybrid photocatalyst has also been demonstrated. This study presents a simple and effective technique for fabricating MOF-based hybrid catalysts for photocatalytic applications.
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Hollow heterostructured catalysts have been widely applied in photocatalytic organic reactions due to their advantages of structure and solar energy utilization. However, achieving optimized hollow structure and components simultaneously in the hybrid photocatalyst system is a huge challenge. Herein, this paper proposes the synthesis of Cu-BTC@CuS@CeO2 ternary heterostructure hollow octahedron using copper-based metal–organic frameworks (Cu-BTC) as the template. Under hydrothermal conditions, a CeO2 nanolayer was formed on the Cu-BTC octahedron surface. Meanwhile, the Cu-BTC octahedrons were controllably etched by this process, leading to the formation of hollow octahedron structure of Cu-BTC@CeO2. After further sulfidation reaction, the Cu-BTC@CuS@CeO2 hollow octahedron formed. By adjusting the sulfidation reaction time, different samples of Cu-BTC@CuS@CeO2 and CuS@CeO2 can be selectively synthesized. The optimized Cu-BTC@CuS@CeO2 sample exhibited a significantly higher visible-near infrared light oxidation activity of amines to imines at room temperature compared to single component catalysts (Cu-BTC, CeO2, and CuS) and binary hybrid catalysts (Cu-BTC@CeO2 and CuS@CeO2). The significantly enhanced photoactivity of Cu-BTC@CuS@CeO2 was attributed to the synergy of hollow octahedron structure, excellent visible light absorption, and fast charge separation caused by the multipath charge transfer in Cu-BTC@CuS@CeO2 double p-n heterojunction. The photocatalytic products and reaction mechanism was investigated by surface-enhanced Raman spectroscopy, gas chromatography-mass spectrometry, and pyridine adsorption FT-IR spectroscopy. This work presents a promising strategy for the design of multi-component hollow heterostructure catalysts.
During the photocatalytic CO2 conversion process, fast charge transport, abundant active sites, and high visible light utilization in photocatalysts are key to achieving excellent CO2 conversion efficiency. In this work, we have designed and prepared hierarchical CuS@SnS2 p-n heterostructure hollow cubes for photocatalytic CO2 reduction. A monolayer of CuS was first formed on the Cu2O cubes to construct core-shell Cu2O@CuS cubes by sulfidation of Cu2O cubes. The following etching leads to the formation of CuS hollow cubes. Finally, CuS@SnS2 p-n heterostructure hollow cubes were obtained by growing SnS2 nanosheets on the CuS hollow cubes. The prepared CuS@SnS2 p-n heterostructure hollow cubes showed an improved efficiency of photocatalytic CO2 reduction compared with the bare CuS and SnS2 control samples, and exhibiting CO and CH4 yields of 235.3 and 107.6 μmol g-1 h-1, respectively. The p-n heterojunction formed between SnS2 and CuS as well as its hollow structure enhanced the charge carrier separation and the light absorption capacity of the hybrid catalyst. Furthermore, after the loading of Au nanoparticles, the formed Schottky junction further discouraged the carrier recombination. Thus, the cooperative p-n heterojunction and Schottky junction greatly facilitated photocatalytic CO2 reduction. This work presents an efficient design of high-performance catalysts for photocatalytic CO2 reduction.
Solar-driven photocatalytic conversion of CO2 into high-value-added fuels has attracted widespread attention; however, the relatively low conversion efficiency has severely constrained photocatalytic applications. This paper constructs binary Cu-BTC@TiO2 catalysts with adjustable inner cavity using copper-based metal organic framework (Cu-BTC) octahedrons as substrate via a solvothermal reaction. In this process, the inner Cu-BTC octahedrons can be controllably etched into a hollow octahedral structure in the presence of HF. Subsequently, Cu-BTC@CuSe@TiO2 hollow octahedrons (HOs) were fabricated by selenization reaction and have various properties such as abundant active sites for CO2 adsorption and reduction reactions, shortened charge transfer distance to prevent electron-hole recombination, and internal reflection/scattering effects to improve solar light utilization. Moreover, the formed novel dual p-n heterostructures between p-type CuSe and n-type semiconductors (Cu-BTC and TiO2) effectively promote spatial separation and migration of charge carriers. The synergistic effect of these advantages makes the Cu-BTC@CuSe@TiO2 HO catalyst with optimized structure and composition exhibit remarkable CO2 photoreduction performance with a CO production rate of 72.3 μmol h-1 g-1 and near 100% selectivity. This work opens a new pathway for designing highly active photocatalysts with excellent product selectivity.
Converting CO2 into useful chemicals or fuels through photocatalysis makes an important contribution to mitigating energy shortages and climate change. Effective separation of photogenerated charges, as well as related surface states, plays a crucial role in semiconductor photocatalytic system for efficient photocatalytic CO2 reduction. Herein, to enhance the performance of In2O3 on photocatalytic CO2 reduction, we prepared unique N-doped In2O3 double-shell hollow dodecahedrons coupled with Au and Co3O4 dual-cocatalysts (Au/N-In2O3/Co3O4). The unique double-shell hollow structure of Au/N-In2O3/Co3O4 enables multiple reflections of incident light, leading to enhanced light absorption and utilization efficiency. Furthermore, the modification of N-In2O3 photocatalyst with dual-cocatalysts enhances CO2 adsorption capacity, and improves charge-carrier separation efficiency. Furthermore, the synergistic interaction between N doping and oxygen vacancies can further increase visible light absorption and CO2 adsorption capacity. These advantages lead to the enhanced photocatalytic activity of the optimized Au/N-In2O3/Co3O4 hybrid photocatalyst, and the average yields of CO and CH4 under simulated sunlight irradiation were 96.1 and 19.9 μmol h-1 g-1, respectively. This work reports a feasible strategy for establishing In2O3-involved excellent photocatalytic CO2 reduction system.
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