Nickel Sulfide Modified Titania Thin Films for Photocatalytic Applications
Melissa Egger a, Marco Sigl a, Thomas Rath a, Ilie Hanzu a, Fernando Warchomicka b, Marlene Kienberger c, Gregor Trimmel a
a Graz University of Technology, Institute for Chemistry and Technology of Materials (ICTM), NAWI, Stremayrgasse, 9, Graz, Austria
b Graz University of Technology, Institute of Materials Science, Joining and Forming (IMAT)
c Graz University of Technology, Stremayrgasse 9, Graz, 8010, Austria
Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS23 & Sustainable Technology Forum València (STECH23) (MATSUS23)
#Adinos - Advances in inorganic thin film semiconductors for solar energy conversion: From photovoltaics to solar fuels
València, Spain, 2023 March 6th - 10th
Organizer: Sudhanshu Shukla
Poster, Melissa Egger, 330
Publication date: 22nd December 2022

The growing energy demand and the endeavor to meet this demand employing renewable sources makes the development of technologies for the efficient utilization of renewable sources such as solar energy very necessary. An important field of research is the solar-powered generation of chemical fuels, among others hydrogen. So far, hydrogen is mainly produced from fossil sources, but there is a lot of research regarding a transition to more renewable production technologies going on. Apart from the generation of hydrogen using photovoltaic integrated electrochemical systems, there is also the possibility of utilizing solar energy using photo(electro)chemical water splitting. [1] A promising material for photocatalytic hydrogen production is TiO2, which is non-toxic, robust, cheap, and abundant. However, its efficiency is limited as it has a large band gap and consequently absorbs only the ultraviolet part of the solar spectrum. In addition, it exhibits a rapid recombination of photogenerated holes and electrons and a large hydrogen evolution overpotential. [2]

Therefore, the use of cocatalysts is necessary, both to narrow the band gap and thus enable the catalyst to utilize the visible part of the solar spectrum, and to enhance charge carrier separation, thereby increasing the efficiency. For this, noble metals such as Pd and Pt are often used. Another potential group of compounds, which is extensively researched to replace those expensive cocatalysts, are metal sulfides. They generally exhibit a lower band gap than TiO2 and therefore enable visible light absorption. [3] A promising strategy for the preparation of metal sulfide nanomaterials are single-source precursors, such as metal xanthates, which can be used for a facile preparation of nanoparticles or thin films with a good control over stoichiometry, phase and morphology depending on the design of the ligand. [3]

 

In this poster the preparation of two types of porous metal sulfide modified titania thin films is presented: Firstly, titania nanotubes are prepared by a two-step anodization of titanium foil and annealed to convert the amorphous TiO2 to the anatase phase, yielding a 7.4 µm film of nanotubes with diameters of approximately 120 nm. In the following step the nanostructures are infiltrated with nickel xanthate precursors, which are then thermally converted to nickel sulfide. This method allows for the preparation of very thin and homogeneous films of nickel sulfide.

Secondly, mesoporous TiO2 films with a thickness of approximately 0.5 µm are prepared by spin coating of a commercial TiO2 paste (Dyesol NRD-30) and similarly modified with nickel xanthates. The prepared films are characterized using XRD, FT-IR spectroscopy, profilometry, optical microscopy and SEM. Their photocatalytic performance is studied using dye degradation and hydrogen evolution experiments with sacrificial electron donors.

Funding for this work is provided by Graz University of Technology through the Lead Project Porous Materials at Work for Sustainability (LP-03)

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