Desulphurization performance of TiO₂-modified activated carbon by a one-step carbonization-activation method

<p>In this study, TiO₂ powder was used as the additive to directly blend with raw bituminous coal and coking coal for preparing modified activated carbon (Ti/AC) by one-step carbonization-activation method. The Ti/AC samples were prepared through blending with different ratios of TiO₂ (0–12 wt%) and their desulphurization performance was evaluated. The results show that the desulphurization activity of all Ti/AC samples was higher than that of the blank one, and the highest breakthrough sulphur capacity was obtained at 200.55 mg/g C when the blending ratio of TiO₂ was 6 wt%. The Brunauer-Emmett-Temer results show that the micropores were dominant in the Ti/AC samples, and their textual properties did not change evidently compared with the blank one. The X-ray photoelectron spectroscopy results show that the loaded TiO₂ could influence the relative content of surface functional groups, with slightly higher content of π–π* transitions groups on the Ti/AC samples, and the relative contents of C=O and π–π* transitions groups decreased evidently after the desulphurization process. The X-ray diffraction results show that the anatase TiO₂ and rutile TiO₂ co-existed on the surface of the Ti/AC samples. After the desulphurization process, TiO₂ phases did not change and Ti(SO₄)₂ was not observed on the Ti/AC samples, while sulphate was the main desulphurization product. It can be assumed that SO₂ could be catalytically oxidized into SO₃ by TiO₂ indirectly, rather than TiO₂ directly reacted with SO₂ to Ti(SO₄)₂.</p

Nanoscale Bandgap Tuning across an Inhomogeneous Ferroelectric Interface

We report nanoscale bandgap engineering via a local strain across the inhomogeneous ferroelectric interface, which is controlled by the visible-light-excited probe voltage. Switchable photovoltaic effects and the spectral response of the photocurrent were explored to illustrate the reversible bandgap variation (∼0.3 eV). This local-strain-engineered bandgap has been further revealed by <i>in situ</i> probe-voltage-assisted valence electron energy-loss spectroscopy (EELS). Phase-field simulations and first-principle calculations were also employed for illustration of the large local strain and the bandgap variation in ferroelectric perovskite oxides. This reversible bandgap tuning in complex oxides demonstrates a framework for the understanding of the optically related behaviors (photovoltaic, photoemission, and photocatalyst effects) affected by order parameters such as charge, orbital, and lattice parameters