arXiv subjects

Christopher Schneider

Publications and source records attributed to Christopher Schneider.

4 recordsLinked to original sources

arXiv2020

A Benson-Type Algorithm for Bounded Convex Vector Optimization Problems with Vertex Selection

We present an algorithm for approximately solving bounded convex vector optimization problems. The algorithm provides both an outer and an inner polyhedral approximation of the upper image. It is a modification of the primal algorithm presented by Löhne, Rudloff, and Ulus in 2014. There, vertices of an already known outer approximation are successively cut off to improve the approximation error. We propose a new and efficient selection rule for deciding which vertex to cut off. Numerical examples are provided which illustrate that this method may solve fewer scalar problems overall and therefore may be faster while achieving the same approximation quality.

math.OC↗

arXiv2020

Black Magic in Gray Titania: Noble-Metal-Free Photocatalytic H2 Evolution from Hydrogenated Anatase

"Black" TiO2 has gained increasing interest because of its outstanding properties and promising applications in a wide range of fields. Among the outstanding features of the material is that certain synthesis processes lead to the formation of an intrinsic co-catalytic center and thus enable noble-metal free photocatalytic H2 generation. In this work, we report "grey TiO2" by an appropriate hydrogenation treatment exhibits excellent photocatalytic hydrogen. In this case, by the employment of thermally stable and high-surface-area TiO2 nanoparticles as well as mesoporous particles as the hydrogenation precursor, the appropriate extent of reduction of TiO2 (coloration) and the formation of Ti3+ is the key for the efficient noble-metal-free photocatalytic H2 generation. The EPR results reveal that "grey TiO2" shows stronger Ti3+ feature at g ca. 1.93 than "black TiO2" contributing to the intrinsic catalytic center for H2 evolution.

physics.chem-ph↗

arXiv2020

Optimized FTO seeding enables the growth of high efficient Ta-doped TiO$_2$ nanorod photoanodes

Tantalum doped rutile nanorods were hydrothermally grown on FTO substrates using a new seeding approach. This approach allows the incorporation of high concentrations of up to 4.8 at% tantalum as active doping and results in a significant enhancement of photoelectrochemical water splitting rate (1.8 mA/cm2 at a potential of +1.5 V vs RHE) which corresponds to ca. 1% photocurrent conversion efficiency under AM 1.5, 100 mW/cm2 simulated sunlight irradiation.

physics.chem-ph↗

arXiv2016

Hydrogenated anatase: Strong photocatalytic H2 evolution without the use of a co-catalyst

In the present work we show, how a high pressure hydrogenation of commercial anatase or anatase/rutile powder can create a photocatalyst for hydrogen evolution that is highly effective and stable without the need of any additional co-catalyst. This activation effect can not be observed for rutile. For anatase/rutile mixtures, however, a strong synergistic effect is found (similar to findings commonly observed for noble metal decorated TiO2). ESR measurements indicate the intrinsic co-catalytic activation of anatase TiO2 to be due to specific defect centers formed during hydrogenation.

physics.chem-ph↗