Charges separation, trapping, recombination and interfacial transfer in nanocrystalline, copper-based core/shell semiconducting materials for photoectrochemical water splitting

ID: 2016/21/D/ST4/00221 financed by National Science Centre – Poland

Research project objectives/ Research hypothesis

The progressive lack of fossil fuels and environmental pollution boosts the search for a more efficient employment of renewable energy sources. In this respect, solar energy has been demonstrated to be storable in the form of energy vectors, such as H2, produced through photoelectrochemical water splitting. The goal of the project is to obtain core/shell nanomaterials with high activity towards photoelectrocatalytic hydrogen evolution. The project will introduce a novel architectural core/shell design for the photoelectrocatalytic hydrogen evolution reaction through the development of low-cost photoelectrodes that will functionally integrate absorbing semiconductors and cocatalysts. By tuning the charge transport properties of assembled semiconductors layers and the kinetics of interfacial water reduction, we will obtain highly efficient photoelectrodes with enhanced charge separation state lifetimes. Project will aim to investigate the correlation between morphological features (e.g. particle size, shell thickness, shape of particle, surface area), electronic properties (band gap energy, CB and VB edges potentials, Fermi level, surface states) and efficiency of primary photocatalytic processes such as charge separation, trapping, recombination and interfacial transfer processes. By this project we would like to highlight: there is no other way to obtain stable and efficient photo(electro)catalyst than correct understanding and deep investigation on such primary photocatalytic processes.

Research project methodology

Project will focused on synthesis of novel copper-based core/shell nanostructures for photoelectrocatalytic hydrogen formation. Materials, such as CuI/CuO, CdS/Cu2S, Fe3O4/CuO, CuO/ZnO, Cu2O/CuO and others will be prepared by various routes including solvothermal and hydrothermal techniques, microwave-assisted or ultrasound assisted synthesis. Morphological features of materials will investigated by TEM and SEM techniques. Band structure of photocatalysts, surface traps and density of states will be studied by spectroelectrochemical techniques as well as electrochemical impedance spectroscopy (EIS) and diffuse reflectance spectroscopy. Electronic properties such as potentials of conduction and valence bands edges or potential of Fermi level will determined in various conditions (in dark, under light, under light and applied bias voltage) using specteroelectrochemical measurements and EIS. Primary photocatalytic processes such as charge generation, their recombination, migration, trapping and interfacial transfer will be investigated by, EXAFS, XANES, FEXRAV including time-resolved measurements, in collaboration with synchrotron radiation facility as well as using photoelectrochemical and spectroelectrochemical measurements.

Expected impact of the research project on the development of science, civilization and society

It is more and more discerned that alongside novel photo(electro)catalysts developments, improved knowledge of the charge transfer, trapping and recombination dynamic is crucial for their technological development. In this context, present project will focused on understanding the optical, electronic and catalytic features of core/shell photomaterials, investigating the nature of electronic transitions and the factors that influence the interaction between the photocathode surface and liquid. The combination of low-cost core/shell materials with high efficiency in sunlight harvesting, for generating electrons/holes pairs to be used to drive the desired redox reactions, is the key point for bringing artificial photosynthesis from the research labs to the everyday life. The present project approach to this problem is to obtain very efficient core/shell nanocomposites based on copper. Through the wavefunction engineering of different semiconductors, the present project will introduce a novel architectural design for the photocatalytic water splitting reaction. As such, the proposed project will have an important impact both from a scientific point of view and possibly being the starting point for future industrial involvement. In particular, the precise control and understanding of charge transport properties is a crucial requirement for artificial photosynthetic systems. This will obtained by detailed analysis of charge trapping, recombination and charge transfer processes. The project and its results will strongly impact in the basic physics and chemistry of semiconductors as well as enhance the understanding of their integration to design efficient photoelectrodes. The contents and objectives of the presented project fit with the guidelines of the European framework programme for research and innovation as well as National Smart Specialisation in Poland. The final goal of the project is the development of photoelectrodes able to produce H2 from water and thus a solar fuels for the growing need of providing to the society secure, clean and efficient energy sources.

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Project effects – Papers

    • Tomasz Barana, Alberto Visibile, Szymon Wojtyła, Marcello Marelli, Stefano Checchia, Marco Scavini, Francesco Malara, Alberto Naldoni, Alberto Vertova, Sandra Rondinini, Alessandro Minguzzi, Reverse type I core – CuI /shell – CuO: A versatile heterostructure for photoelectrochemical applications, Electrochim. Acta. 2018, 266, 441-451

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    • Szymon Wojtyła, Konrad Szmit, Tomasz Baran, Type II Heterostructures: The Way Towards Improved Photoelectrochemical Activity of Graphitic Carbon Nitride, J. Inorg. Organomet. Polym. 2018, 28, 492?499

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    • Tomasz Baran, Szymon Wojtyła, Alessandro Minguzzi, Sandra Rondinini – Photoelectrochemical and photocatalytic systems based on titanates for hydrogen peroxide formation, J. Electroanal. Chem. 2018, 808, 395-402

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