查看更多>>摘要：Removal of formaldehyde (HCHO) has recently been attracted much attention, and completely catalytic oxidation at room temperature has been identified as one of the efficient routes for solving this problem. In this research, we show a successful preparation of Ag-loaded octahedral molecular sieve from solvent-free route (Ag/OMS-2-S), which was characterized by XRD, SEM, HRTEM, BET, XPS, ICP-OES, H-2-TPR, and HCHO-TPD techniques to investigate the factors influencing the catalytic activity. Very interestingly, HCHO is completely converted into CO2 at room temperature over the Ag/OMS-2-S catalyst. To the best of our knowledge, this is the first time for complete oxidation of HCHO at room temperature over all the Ag-based catalysts. Relating to the characterizations, it is suggested that the active oxygen species play a key factor that contributes to the excellent performance of the Ag/OMS-2-S. In addition, the Ag/OMS-2-S catalyst is also very stable and selective. Combination of extraordinary activity and excellent stability of the Ag/OMS-2-S catalysts might offer an alternative way to develop new efficient catalysts for the removal of air pollutants.
查看更多>>摘要：The current study investigates Ce-modified SrFeO3-delta oxygen carriers for oxidative dehydrogenation (ODH) of ethane coupled with CO2 splitting in a chemical looping manner. During 39 cycles of redox testing over the sample of 0.2Ce/SrFeO3, up to 29% ethane conversion and 82% ethylene selectivity are achieved, and the CO generation in the subsequent CO2 splitting step is 0.25 mmol/g. XPS characterization results indicate decreased Fe2+/(Fe3++Fe4+) ratio as well as increased active oxygen species proportion on the near-surface of Ce-modified samples, which are responsible for the improved activity of the 0.2Ce/SrFeO3 in ethane ODH reaction. DFT calculations further reveal that the increased ODH activity of 0.2Ce/SrFeO3 is due to the lower surface oxygen vacancy formation energy upon Ce promotion. Moreover, the higher resistance of lattice oxygen diffusion from the bulk to the surface is the main reason for the superior ethylene selectivity attained by the CO2-regenerated sample than that by O-2 regeneration.
查看更多>>摘要：High-entropy oxides (HEOs), as a new family of materials with five or more principal cations, have shown promising properties for various applications. In this work and inspired by inherent defective and strained structure of HEOs, photocatalytic CO2 conversion is examined on a dual-phase TiZrNbHfTaO11 synthesized by a two-step high-pressure torsion mechanical alloying and high-temperature oxidation. The HEO, which had various structural defects, showed simultaneous photocatalytic activity for CO2 to CO and H2O to H2 conversion without the addition of a co-catalyst. The photocatalytic activity of this HEO for CO2 conversion was better than conventional photocatalysts such as anatase TiO2 and BiVO4 and similar to P25 TiO2. The high activity of HEO was discussed in terms of lattice defects, lattice strain, light absorbance, band structure, photocurrent generation and charge carrier mobility to activation centers. The current study confirms the high potential of HEOs as a new family of photocatalysts for CO2 conversion.
查看更多>>摘要：Polymeric carbon nitride (g-C3N4) exhibits only mediocre catalytic activity in photocatalytic environmental remediation and energy conversion because of its limited light absorption and sluggish charge transfer. Herein, we assembled novel, tubular carbon nitride (D-TCN450) with nitrogen defects/boron dopants via a self-supramolecular reaction and NaBH4 thermal reduction approach. Advanced characterization results suggested that introducing the nitrogen defects/boron dopants can effectively promote light trapping, charge separation, and valance-band downshift. Density functional theory and electron spin resonance results further proved that the fusion of cyano groups (nitrogen defects) into the framework of D-TCN450 can facilitate oxygen adsorption to form superoxide radicals. As a result, D-TCN450 exhibited dramatically improved photocatalytic hydrogen evolution and photodegradation of tetracycline hydrochloride at a 4- and 9-fold enhancement compared to pristine g-C3N4, respectively. This integrated engineering strategy might provide a unique paradigm for the rational design of novel photocatalysts for sustainable remediation and energy innovation.
NSTL
Elsevier