Institute of Solid State Physics

M-ERA-NET project

Multiscale computer modelling, synthesis and rational design of photo(electro)catalysts for efficient visible-light-driven seawater splitting (CatWatSplit)

Project partners and contact persons

Project start: 01/05/2021

Project end: 30/04/2024

TRL:

at the beginning of the project: 2

at the end of the project: 4

Project summary

The project aimed to develop efficient catalysts for seawater splitting to produce hydrogen and chlorine-based disinfectants. The methodology involved several key steps. First, theoretical modelling using Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) was employed to predict the electronic structure and absorption spectra of potential photocatalysts, as well as non-adiabatic molecular dynamics (NAMD) simulations were conducted to understand charge transfer processes at the catalyst-water interfacepredicting the energetics of hydrogen and chlorine evolution reactions. Next, the synthesis of catalysts involved creating micro/nanostructured photo(electro)catalysts such as WO₃, BiVO₄, and their heterostructures using methods like sol-gel, hydrothermal, and electrodeposition has been performed. These catalysts were modified with metal doping and heterostructuring to enhance their properties. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to analyze the structural and chemical properties of the synthesized catalysts. Optoelectronic properties were assessed using UV-Vis spectroscopy and photoluminescence (PL) spectroscopy. The project also involved designing and fabricating a photoelectrochemical (PEC) reactor prototype with a sandwich-type configuration to separate hydrogen and oxygen using a Nafion membrane. Computational fluid dynamics (CFD) simulations were conducted to optimize reactor performance. Performance testing evaluated the photocatalytic and PEC performance of the catalysts in chloride-containing solutions and artificial seawater, measuring the efficiency of hydrogen and chlorine production through chronoamperometry and iodometric titration.

The project results in elaborated reliable theoretical approach based on insights from DFT and TDDFT calculations provided valuable predictions on the bandgap engineering and charge transfer mechanisms of the catalysts, guiding the synthesis process. The synthesized WO₃ and BiVO₄ catalysts, along with their heterostructures, demonstrated significant photocurrent densities and stability in chloride solutions. The optimal heterostructures showed enhanced selectivity for formation of reactive chlorine species over oxygen evolution reaction. The PEC reactor prototype achieved high hydrogen purity (98%) and efficient separation of hydrogen and oxygen gases. Targeting TRL4 has been achieved within the project. Based on results obtained within the project 13 scientific papres have been published, 15 presentations at scientific conferences have been made, and 3 PhD theses have been prepared.

Within the project have been successfully developed and tested novel photocatalysts for seawater splitting, achieving significant advancements in both theoretical understanding and practical applications. The combination of theoretical modelling and experimental synthesis led to the development of catalysts with improved efficiency and stability for seawater splitting. The project demonstrated the feasibility of using seawater as a sustainable resource for hydrogen and chlorine-based disinfectant production, contributing to clean energy and environmental sustainability. The findings pave the way for further optimization and scaling up of PEC systems for industrial applications, potentially transforming the landscape of renewable energy and chemical production. The project highlights the importance of interdisciplinary collaboration and the integration of theoretical and experimental approaches in advancing materials science and sustainable technologies.