Titanium metal–organic frameworks (Ti‐MOFs), as an appealing type of artificial photocatalyst, have shown great potential in the field of solar energy conversion due to their well‐studied photoredox activity (similar to TiO2) and good optical responsiveness of linkers, which serve as the antenna to absorb visible‐light. Although much effort has been dedicated to developing Ti‐MOFs with high photocatalytic activity, their solar energy conversion performances are still poor. Herein, we have implemented a covalent‐integration strategy to construct a series of multivariate Ti‐MOF/COF hybrid materials PdTCPP⊂PCN‐415(NH2)/TpPa (composites 1, 2, and 3), featuring excellent visible‐light utilization, a suitable band gap, and high surface area for photocatalytic H2production. Notably, the resulting composites demonstrated remarkably enhanced visible‐light‐driven photocatalytic H2evolution performance, especially for the composite 2 with a maximum H2evolution rate of 13.98 mmol g−1 h−1(turnover frequency (TOF)=227 h−1), which is much higher than that of PdTCPP⊂PCN‐415(NH2) (0.21 mmol g−1 h−1) and TpPa (6.51 mmol g−1 h−1). Our work thereby suggests a new approach to highly efficient photocatalysts for H2evolution and beyond.
It has been rarely reported the morphological control of derivatives of metal‐organic frameworks (MOFs) in hydrothermal conditions for photocatalytic applications. We report here a family of highly efficient composite photocatalysts composed of terephthalic acid/terephthalate (TPA) ligand and TiO2with various morphologies (e. g., nanoparticles, nanosheets, and nanorods). The composites are synthesized by a simple one‐step hydrothermal method in various solvents (i. e., H2O, HF, H2SO4, HCl, and HNO3) using Ti‐based MOF (MIL‐125(Ti)) as precursor. The formation mechanism of composite materials with different morphological features is discussed. Impressively, the composite of TiO2nanoparticles/TPA synthesized using H2O as solvent under hydrothermal condition exhibits the highest photocatalytic H2activity among the studied materials, with a photocatalytic H2production rate of 6.38 mmol g−1 h−1, which is approximately 7.5‐fold higher than pure TiO2(Degussa, P25) and prominent apparent quantum efficiency (AQE) of 65 % at 365 nm. Furthermore, the mechanism of boosted photocatalytic H2production is discussed.
more » « less- NSF-PAR ID:
- 10401201
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – A European Journal
- Volume:
- 29
- Issue:
- 21
- ISSN:
- 0947-6539
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Abstract Titanium metal–organic frameworks (Ti‐MOFs), as an appealing type of artificial photocatalyst, have shown great potential in the field of solar energy conversion due to their well‐studied photoredox activity (similar to TiO2) and good optical responsiveness of linkers, which serve as the antenna to absorb visible‐light. Although much effort has been dedicated to developing Ti‐MOFs with high photocatalytic activity, their solar energy conversion performances are still poor. Herein, we have implemented a covalent‐integration strategy to construct a series of multivariate Ti‐MOF/COF hybrid materials PdTCPP⊂PCN‐415(NH2)/TpPa (composites 1, 2, and 3), featuring excellent visible‐light utilization, a suitable band gap, and high surface area for photocatalytic H2production. Notably, the resulting composites demonstrated remarkably enhanced visible‐light‐driven photocatalytic H2evolution performance, especially for the composite 2 with a maximum H2evolution rate of 13.98 mmol g−1 h−1(turnover frequency (TOF)=227 h−1), which is much higher than that of PdTCPP⊂PCN‐415(NH2) (0.21 mmol g−1 h−1) and TpPa (6.51 mmol g−1 h−1). Our work thereby suggests a new approach to highly efficient photocatalysts for H2evolution and beyond.
-
more » « less
Abstract In this study, Mg2+‐doped mesoporous TiO2photocatalysts derived from Mg2+adsorption (MA) process on MIL‐125, a metal‐organic framework material, were prepared and employed for photocatalytic reduction of CO2to produce CO. The Mg2+doping concentration was controlled by varying the Mg2+concentration in the Mg2+adsorption process. It was demonstrated that the Mg2+doping promoted the generation of surface Ti3+and significantly increased transient photocurrent density. Over a 4 h UV/Vis irradiation period, the best performing photocatalyst, 1MA, delivered a CO production rate ∼20 times higher than that of P25, a commercially available TiO2nanopowder. It is believed that the Mg2+adsorption process introduced more favorable properties to the TiO2photocatalysts, such as higher surface area and porosity for more reactive sites, and concentrated surface Ti3+centers for improved charge transfer.
-
more » « less
Anatase TiO2is a promising anode material for lithium‐ion batteries (LIBs) owing to its low cost and stability. However, the intrinsically kinetic limits seriously hindered its lithium‐ion storage capability. Here we present that anatase TiO2with rich oxygen vacancies can enhance its lithium‐ion storage performance. We synthesize anatase TiO2with well‐retained hierarchical structure by annealing the H2Ti5O11·3H2O yolk‐shell spheres precursor in nitrogen atmosphere. EPR and XPS data evidence that the oxygen‐deficient environment could generate abundant oxygen vacancies in the as‐derived anatase TiO2, which leads to improved electron conductivity and reduced charge‐transfer resistance. The rich oxygen vacancies and high structural integrity of the hierarchical yolk‐shell spheres enable the as‐derived anatase TiO2yolk‐shell spheres with a high specific capacity of 280 mAh g−1at 100 mA g−1and 71% of capacity retention after 5000 cycles at 2 A g−1.
-
more » « less
Abstract Photo‐responsive semiconductors can facilitate nitrogen activation and ammonia production, but the high recombination rate of photogenerated carriers represents a significant barrier. Ferroelectric photocatalysts show great promise in overcoming this challenge. Herein, by adopting a low‐temperature hydrothermal procedure with varying concentrations of glyoxal as the reducing agent, oxygen vacancies (Vo) are effectively produced on the surface of ferroelectric SrBi4Ti4O15(SBTO) nanosheets, which leads to a considerable increase in photocatalytic activity toward nitrogen fixation under simulated solar light with an ammonia production rate of 53.41 µmol g−1h−1, without the need of sacrificial agents or photosensitizers. This is ascribed to oxygen vacancies that markedly enhance the self‐polarization and internal electric field of ferroelectric SBTO, and hence, facilitate the separation of photogenerated charge carriers and light trapping as well as N2adsorption and activation, as compared to pristine SBTO. Consistent results are obtained in theoretical studies. Results from this study highlight the significance of surface oxygen vacancies in enhancing the performance of photocatalytic nitrogen fixation by ferroelectric catalysts.
