Project main goal
The goal of this project is to elaborate various photocatalytic and hybrid photocatalytic/catalytic materials with significantly improved efficiencies of quantum solar energy utilization. The project assumes design and synthesis of new photocatalysts in various forms offering high efficiencies of oxidation of organic pollutants or high quantum yield of photon to chemical energy conversion. Targeted quantum yields for energy downhill reactions should exceed the value of one due to combination of photocatalytic and catalytic reactions. A variety of photoactive catalysts, including hierarchical photocatalytic/catalytic materials, photonic/photocatalytic hybrid materials, and defected materials with fine-tuned electronic properties will be designed and studied. The photocatalysts will be optimized towards their application in photocatalytic removal of pharmaceutically active compounds (antibiotics, hormones, anti-inflammatory drugs) from waters.
The team working on the project will consist of the project leader, three post-doctoral fellows, four PhD students and several students. The first young doctor will be employed in September 2017 and will work until the end of the project, the second one will be employed since September 2017 for one year and the third one will join the team for the last two years (September 2018 – August 2020). 4 PhD and 3 undergraduate students will be involved during the whole project (each year undergraduate students will be involved in 3 out of 4 sub-projects). Since every student will be a member of the team for one to two years, the total number of students participating in the project will be not lower than 6 and not higher than 9. It is assumed, that 3 additional technicians and young doctors will be involved (with a non-full time employment). Cooperation with six scientific groups (five from abroad, one from Poland) is also planned. The structure of the group headlines of main sub-projects is presented in Fig. 3.
Figure 1. The team structure, main research tasks and cooperation with other groups.
Research planned within this project will be grouped in four sub-projects, each of them associated with one PhD student (light blue boxes in Fig. 1). Cooperation is represented by green boxes, while darker blue boxes present people involved in the sub-projects. The projects focused mainly on (but not limited to) materials dedicated to energy downhill reactions (water treatment) are localized on the left hand side of the scheme, while those dedicated mainly (but not limited) to solar fuels production – on the right hand side. The ongoing project entitled “Engineering of electronic states in semiconductor photocatalysts” (financed by National Science Centre, Poland) can be considered as an associated project aimed to engineer redox properties of photocatalysts.
Project 1. Hierarchical photocatalytic and catalytic materials
(Post-doc #2, PhD #1, Students)
The goals of this sub-project will be focused on development of photocatalytic and photocatalytic/catalytic hybrid materials with enhanced photocatalytic activity mainly dedicated to water treatment. Such materials will often show a hierarchical architecture, which offers a multitude of channels and pores. They will generally belong to one of two groups of materials: composed of a photocatalytically active mesoporous matrix with catalytic sites deposited inside pores, or a catalytically active porous matrix with embedded or immobilized photocatalysts. Controlled structure of the porous materials should enable adsorption of pollutants and oxygen increasing their concentration in microreactors formed in this way. High concentrations of substrates in pores should assure conditions under which not one but several elemental oxidation steps initiated by one electron/hole pair could take place. In such a case, the quantum yields of degradation processes should exceed a unity.
Project 2. Photonic materials for photocatalytic applications
(PhD #2, Post-docs, Students)
The aim of this sub-project is to develop and test photonic materials that would enable increase of the density of absorbed light at photocatalytic sites. Beside the expected effect of a higher electrons and holes availability resulting from their higher generation rate per volume unit, we expect to observe also the effect of local heating due to increased rate of recombination processes. Recombination is disadvantageous considering quantum efficiencies of photocatalytic processes, but local heating should foster the catalytic (dark) parts of oxidation reactions (energy downhill processes). Therefore, materials developed within this sub-project will be optimized towards applications both for solar fuels production (water splitting, carbon dioxide to methanol conversion), but also pollutants degradation. Achievements of other sub-projects will be applied to enhance the performance of photocatalytic/catalytic hybrid materials.
Project 3. Defected materials in photocatalysis
(PhD #3, Post-docs, Students)
The development of active photocatalysts should take into account the role of bulk properties of the photocatalyst, the properties of the outer layers (interface) and chemistry of surface processes. Chemistry of solid state, including defects, dopants etc., influences the electronic properties of the material. Moreover, interaction of the bulk with the outer layers of the crystal together with its surface results in unique electronic properties of the whole crystal. Such properties determine the fate of photogenerated charges (recombination, transport to various crystal facets and surface sites, mobility, lifetimes, redox properties of the surface trapped charges etc.), as well as several other crucial parameters (Fermi level, bandgap, adsorption properties etc.). The goal of this sub-project is to combine the material science of solids and chemistry of defects with surface chemistry to understand better processes and photoprocesses taking place at solid/liquid or solid/gas interfaces. This knowledge should enable defining the crucial parameters and properties influencing water oxidation, which play a pivotal role in photocatalytic water splitting, and other photocatalytic processes. This interdisciplinary approach should result in designing of more active photocatalysts for various applications.
Project 4. Downhill and uphill photocatalytic processes – towards applications
(PhD #4, Post-doc #1, Students)
The knowledge gained in sub-projects 1-3 will be implemented in applied studies aimed at preparation of the product (photocatalyst or technology) suitable for a patent protection and commercialization. Our efforts within this sub-project will involve optimization of the selected, most promising systems developed within sub-projects 1-3. In particular, photocatalysts with highly improved quantum yields of oxidation of organic pollutants (including anthropogenic pollutants, antibiotics, hormones and anti-inflammatory drugs), possibly exceeding a value of 1, should emerge. The materials can be also engineered to facilitate CO2 reduction or water splitting. A potential cooperation with an industrial partner (not selected yet) cannot be excluded at this stage.
Quantum chemical calculations (support to all sub-projects)
The presented sub-projects will be supplemented by computational methods. They will include modelling of the surface of developed photocatalysts and catalysts, as well as their interactions with adsorbed substrates. A particularly important task will involve calculation of density of states for developed materials, which can be compared with DRS-SEC and DB-PAS measurements. Detailed analysis of primary chemical reactions taking place at the surface of photocatalysts will be supported by modelling of the reaction paths.
Associated Project: Engineering of electronic states in semiconductor photocatalysts
The TEAM project will be associated with the project entitled “Engineering of electronic states in semiconductor photocatalysts” financed by National Science Centre within the OPUS program (2016-2019; 2015/19/B/ST5/00950). The goal of this project is to synthesize photocatalysts with controlled distribution of electronic states within the bandgap and to understand correlations between photocatalytic activity of the semiconductor and its density of states (DOS).