Metal-organic framework-based materials for photoelectrochemical water-splitting a study of the in-situ growth and effects of Cu-BDCNH2 on cuprous oxide-based photo-cathodes

The increasing demand for energy coupled with environmental issues, lets researchers seek out renewable, and particularly environmentally friendly alternatives to traditional fossil fuels. Photo-electrochemical (PEC) water splitting procedures display a promising route to produce hydrogen as a zero-emission energy carrier in a green manner. In this regard, the exploration of proper photo-active materials to construct PEC cells as well as finding suitable co-catalysts is of great interest. Especially, p-type cuprous oxide (Cu2O) has been intensively studied due to its favorable band energy position, earth abundance, and low toxicity. However, established techniques such as atomic layer deposition (ALD) to produce highly efficient Cu2O-based PEC cells are costly and not commercially applicable. Therefore, metal-organic frameworks (MOFs) - a class of porous materials recognized for their enhanced specific surface area and catalytic abilities - are investigated for their application in PEC water splitting. Thus, the aim of this thesis is to explore the photo-cathodic behavior of cuprous oxide (Cu2O), its enhancement in PEC performance using overlayers of different nature (metal
oxides and polymer-based), and particularly creating a unique combination with a copper-based metal-organic framework, namely Cu-BDCNH2. As the synthesis of this MOF in this matter has not been implemented yet to the best of our knowledge, various settings and conditions have been tested to allow the growth of a continuous MOF layer onto the Cu2O substrate film. To do so other literatures were used as starting points and adapted accordingly. Afterward, the obtained Cu2O/MOF system has been tested and analyzed through various methods (XRD, FTIR, XPS, SEM, EDS) and compared to existing literature. By combining MOF and Cu2O, it was ultimately possible to achieve a photo-current density of 1.5 mA/cm2, without the need for additional co-catalyst.