- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Photocatalytic reduction of CO2 to methane over PtOx-loaded ultrathin Bi2WO6 nanosheets
摘要： Solar CO2 photoreduction into hydrocarbons is promising and significative. However, many conventional catalysts reported usually suffer from poor photocatalytic activities. Herein, ultrathin Bi2WO6 nanosheets with a thickness of about 4.8 nm have been synthesized by hydrothermal method, which exhibited a CH4 production rate of 19 ppm g?1 h?1 under a low CO2 concentration of 400 ppm. PtOx nanoparticles with a size of about 2 nm were then loaded on the Bi2WO6 nanosheets as excellent co-catalysts by photoreduction in aqueous solution, and an optimal CH4 yield of 108.8 ppm g?1 h?1 was achieved, which was about 5.7 times than that of pristine Bi2WO6 nanosheets. Further analyses of photocurrent curves, electrochemical impedance spectroscopy and polarization curves of water oxidation indicated that the improved photocatalytic activity was suggested to result from the enhanced carrier separation and accelerated water oxidation by PtOx nanoparticles. The work will likely give a deeper insight of PtOx nanoparticles and provide a new idea to design catalysts for CO2 photoreduction to CH4.
关键词： PtOx nanoparticles,Carrier separation,Water oxidation,CO2 photoreduction,Bi2WO6 nanosheets
更新于2025-09-10 09:29:36
-
Enhanced activity of β-Ga2O3 by substitution with transition metal for CO2 photoreduction under visible light irradiation
摘要： Gallium oxide semiconductors have been developed as effective photocatalysts for water splitting driven by UV light irradiation, but there is no relevant study for the CO2 photoreduction application. Herein, we report the first investigation of β-Ga2O3 applying to photocatalytic CO2 reduction under visible light irradiation by doping transition metal ions (M = V, Cr, Mn, Fe, Co, Ni and Cu) onto the framework. Using sol-gel method, a series of transition metal ions incorporated β-Ga2O3 have been successfully obtained, in which the transition metal substitution content is 2 mol %. The β-Ga2O3:M photocatalysts are characterized completely by diverse tests (e.g., XRD, XPS, UV-Vis DRS, SEM). The effective replacement of Ga3+ ion by M ions significantly expands the scope of spectral response from UV light to visible light, and Fe3+, Co2+, Ni2+ significantly enhance the photocatalytic activity under visible light irradiation. In these cases, CO and H2 are evolved as the reduction products from CO2 and H+ by the generated electrons, respectively. Among these effective catalysts we prepared, β-Ga2O3:Ni exhibits the most substantial CO formation rate of 14.3 μmol/h at 30 °C, and the selectivity for CO evolution exceeds 60.9 %. Furthermore, the CO formation rate increases to 24.6 μmol/h after loading of Ag as the co-catalyst. The stability of the Ag/β-Ga2O3:Ni are verified after five cycle of CO2 photoreduction under visible light.
关键词： transition metal substituted,visible light irradiation,CO2 photoreduction,gallium oxide
更新于2025-09-10 09:29:36
-
Light irradiation enhanced CO2 reduction with methane: A case study in size-dependent optical property of Ni nanoparticles
摘要： Ni/Al2O3 catalysts and bulk Ni nanoparticles, with the average sizes of Ni particles varying from 2.7 nm to 238.0 nm, were synthesized and evaluated in CO2 photoreduction with methane (CRM). It was found that the catalytic activities of the Ni-based catalysts were all increased almost linearly with light intensity in the range of 0–1.07 W cm?2, with the optical properties of Ni particles being regarded to account for the activity enhancement. Wavelength dependent performance study suggested that Ni LSPR dominated for the optical property of smaller Ni nanoparticles whereas interband transition played gradually increased role in improving the activities over larger Ni particles. To the best of our knowledge, it is the first time to study the size-dependent optical properties of Ni nanoparticles, meanwhile, this study offers a foundation to further improve the efficiency of Ni-based catalysts in CO2 utilizations.
关键词： Ni nanoparticles,Interband transition,CO2 photoreduction,Localized Surface plasmon resonance,Photocatalysis
更新于2025-09-10 09:29:36
-
Highly efficient photocatalytic reduction of CO2 on surface-modified Ti-MCM-41 zeolite
摘要： Three dimensional microporous zeolites have attracted much attention in catalysis because of their large BET surface area and abundant pores. Herein, Ti-MCM-41 zeolites with different molar ratio of Si/Ti were synthesized, and the surface acidity and active sites were adjusted by the modification of basic-earth metal oxides, and noble metal nanoparticles. The photocatalytic activity and selectivity were evaluated by the reduction of CO2 to CH4 and CO. The results indicated that the efficiency and selectivity of CO2 photoreduction to CH4 of Ti-MCM-41 zeolites were 93 ppm·g-1·h-1 and 29% in the ratio Si/Ti=10 under keeping the zeolite structure, and which is much higher than that of P25 with the value of 24 ppm·g-1·h-1 and 23%. When the surface of Ti-MCM-41 zeolites was modified by different basic-earth metal oxides, the photo-reduction activity of CO2 to CH4 increased about 1.5 times with MgO modification, and the selectivity of CO2 to CH4 improved to 42%. Moreover, the photoactivity and selectivity enhanced to 8835 ppm·g-1·h-1 and 93% when the surface was further decorated by Pt nanoparticles, while the selectivity of CO2 to CO reached 94% when Pd was loaded. Our work reveal reasonably that adjusting the acidity and active site of the microporous zeolites is a highly efficient way to improve the photocatalytic efficiency of CO2 reduction.
关键词： Ti-MCM-41 zeolite,active sites,surface acidity,CO2 photoreduction
更新于2025-09-09 09:28:46
-
Ferroelectric Polarization Promoted Bulk Charge Separation for Highly Efficient CO2 Photoreduction of SrBi4Ti4O15
摘要： Fast recombination of photogenerated charge carriers in bulk remains the major obstacle for photocatalysis nowadays. Developing ferroelectrics directly as photoactive semiconducting catalysts may be promising in view of the strong ferroelectric polarization that induces the anisotropic charge separation. Here, we report a ferroelectric layered perovskite SrBi4Ti4O15 as a robust photocatalyst for efficient CO2 reduction. In the absence of co-catalysts and sacrificial agents, the annealed SrBi4Ti4O15 nanosheets with the strongest ferroelectricity cast a prominent photocatalytic CO2 reduction activity for CH4 evolution with a rate of 19.8 μmol·h-1·g-1 in the gas-solid reaction system, achieving an apparent quantum yield (AQY) of 1.33% at 365 nm, outperforming most of the reported photocatalysts. The ferroelectric hysteresis loop, piezoresponse force microscopy (PFM) and ns-level time-resolved fluorescence spectra uncover that the outstanding CO2 photoreduction activity of SrBi4Ti4O15 mainly stems from the strong ferroelectric spontaneous polarization along [100] direction, which allows efficient bulk charge separation along opposite direction. DFT calculations also disclose that both electrons and holes show the smallest effective masses along a axis, verifying the high mobility of charge carriers facilitated by ferroelectric polarization. This study suggests that the traditionally semiconducting ferroelectric materials that have long been studied as ferro/piezoelectric ceramics now may be powerfully applied in the photocatalytic field to deal with the growing energy crisis.
关键词： CO2 photoreduction,ferroelectric perovskite,spontaneous polarization,SrBi4Ti4O15 nanosheets,piezoelectric-catalysis
更新于2025-09-09 09:28:46