Nano-functionalization of Photoactive Materials for High-Efficient Photoelectrochemical Green Hydrogen Production
The hydrogen gas produced through renewable energy sources such as solar and wind powers has recently been an intensive global discussion as a solution for grey and blue hydrogen production. The new process generally involves a direct reduction of water to form hydrogen gas by photocatalytic and/or photoactive material in the presence of sunlight. Due to the absence of CO2 emission as a side product, the hydrogen product from this particular process is named as “green hydrogen”. With these production characteristics, the green hydrogen production has been regarded as an ideal route both for producing a non-fossil-based energy carrier as well as for decarbonising hydrogen production.
The green hydrogen production from this direct conversion, namely photoelectrochemical (PEC) water reduction, is attractive. This is due to that the photocurrent resulting from the sunlight-photoactive material interaction can reduce the consumption of current from a renewable energy-powered electrical supply.
PEC water reduction to produce H2 faces a challenge of a scenario in which its production should fulfil the global fuel demand. The direct consequence of such a scenario is that the quantity of materials required to produce hydrogen is extremely large. Therefore, the photoactive components for PEC water reduction should arguably contain earth-abundant elements with minimum utilisation of critical raw materials. The arth-abundant elements in vision are oxides and chalcogenides. NanoGreenH2-Pro strives to employ natural micaceous hematite Fe2O3 as the photoanode for enabling oxygen evolution reaction, and kesterite Cu2ZnSnS4 photocathode for hydrogen evolution reaction with emerging Metal-Organic-Framework (MOF) ZIF-8 as co-catalyst to enhance water reduction performance. NanoGreenH2-Pro is a bilateral project between AIT, PMT Powder Processing GmbH and Shanghai University under the Austrian FFG and the Shanghai University R&D Cooperative project.
Project Goals
The NanoGreenH2-Pro ultimate goal is to boost the earth-abundant PEC water reduction device performance in a neutral to mid-alkali electrolyte through new photoelectrode architecture designs encompassing nanoparticles and Metal-Organic Framework (MOF) functionalized-Hematite Fe2O3 and kesterite Cu2ZnSnS4 films. The main task of the project was to enhance the functionality of the photoelectrodes (Cu2ZnSnS4 photocathode and Fe2O3 photoanode) by MOF and/or nanoparticles. The functionalization served as an additional catalyst or protection against the electrolyte used in the PEC setup, thus prolonging the stability as well as boosting the overall PEC water reduction performance. The Shanghai University group synthesised MOFs and nanoparticles, while AIT and PMT Powder Processing GmbH focused on PEC device integration and materials processing for photoelectrode fabrication.
Project results
AIT successfully developed a new PEC device architecture based on kesterite photocathode using kesterite Cu2ZnSnS4/Zn(O,S)/ZnO/Nb-doped TiO2/Pt (see Figure 1). A maximum photocurrent density up to 15 mA/cm2 can be achieved using optimisation of the multilayer’s thickness and overlayer material selection (manuscript under preparation).
Figure 1. A new PEC device photocathode architecture based on earth-abundant Cu2ZnSnS4 proposed by AIT.
Funding
This project was carried out as part of the 38th call for proposals ‘Production of the Future’ by the Federal Ministry for Innovation, Mobility and Infrastructure (BMIMI) in cooperation with Shanghai University, China. It was implemented on behalf of the BMIMI by the Austrian Research Promotion Agency (FFG).
