Editorial In situ operando investigation of catalytic and electrocatalytic interfaces

In situ and operando spectroscopic methods play a fundamental role in a variety of different fields of modern science. In particular, as energy and environmental science have become increasingly important recently, the need of in situ and operando spectroscopic methods has also increased significantly. Therefore, we felt it was time to have a special issue focused on such techniques and for which the aim is to merge the research communities investigating catalytic and photo electrochemical interfaces with different in situ operando spectroscopic techniques, to share recent results, experimental methods, and future perspectives , as we reported in the scope of this special issue. With its 23 original research papers and 2 topical reviews, spanning from heterogeneous catalysis to photoelectrochemistry, we believe that the outcome of this special issue fulfills the aforementioned ai

Electrical spectral technique for measuring Cross-Phase Modulation impact in WDM optical systems

An electrical spectral technique to correctly evaluate cross-phase modulation behavior in intensity modulation-direct detection systems is proposed. Intrinsic advantages of the technique, in terms of high accuracy, are discussed in comparison with the classical time-domain method, which requires precise receiver noise characterization. Measures have been performed with a pump-and-probe scheme on different standard optical communications fibers (i.e., G.652, G.655). The employed pump has been intensity modulated by a nonreturn-to-zero alternate pattern at different bit rates (from 1 to 10 Gb/s), with 0.8- and 1.6-nm pump-probe wavelength spacing. The experimental results are compared with the time-domain technique when accurate calibration is performed

Photocatalytic activity of TiO2-WO3 mixed oxides in relation to electron transfer efficiency

Aiming at producing photocatalysts with minimized photoproduced electron \u2013 hole pairs recombination, a series of titanium \u2013 tungsten mixed oxides has been prepared, by coupling TiO2 with different amounts of WO3, according to an alkaline-catalyzed sol-gel method followed by an incipient wetting procedure. The photocatalysts were characterized by surface and bulk techniques and tested in both an oxidation and a reduction photocatalytic reaction, i.e. in formic acid (FA) mineralization and in Cr(VI) reduction. Tungsten was mainly present as hexagonal WO3 on the TiO2 surface, though a fraction of W migrates into the TiO2 lattice substituting Ti atoms, as evidenced by XRPD analysis. Different photoactivity scales were found in the two test reactions, both occurring in the same pH range under similar substrate-photocatalyst electrostatic interactions. In fact, photoexcited electrons transferred from the conduction band (CB) of TiO2 to the CB of coupled WO3, being energetically unable to reduce O2 molecules, easily recombine with photoproduced holes, with a consequent photoactivity decrease in FA photo-mineralization with increasing W/Ti ratio. On the contrary, coupling TiO2 with small WO3 amounts (0.2-1.0 mol.%) is beneficial in the removal of Cr2O72- anions. These species, being characterized by a redox potential more positive than the CB edge of WO3, may efficiently accept the electrons trapped in WO3 domains, converting into less toxic Cr(III) species. Thus, WO3 surface domains effectively promote photoproduced charge separation by efficiently trapping CB electrons; increased photocatalytic efficiency depends on the redox potential of the electron acceptor species directly (or indirectly) involved in the photocatalytic process