EU Project: NANOSTACKS - Nanostack printing for materials research (active)

Down to the roots, there are two reasons why man-made fuel cells still cannot fulfil their inherent promise: (i) they need expensive platinum electrodes, especially for oxygen reduction, and (ii) their energy efficiency is bad, especially when converting hydrogen into electricity. Hydrogenases (“Nature’s fuel cells”) on the other hand efficiently convert chemical energy into electrical energy and vice versa without employing expensive materials. They do that with a basic trick that nearly all redox-enzymes use: they all control the flow of electrons in nano dimensions by offering a gradient of redox centres that “drag” the electrons to the catalytic centre – similar to gravity that pulls the marble down a predetermined path. The catalytic centre provides a “parking place” for delivered electrons that is made of two iron atoms in optimized distance from each other, while a second “delivery chain” that is made of histidine or glutamate side chains transports protons to the catalytic centre where they react with stored electrons to generate hydrogen (Fig. 1).

This design principle explains why hydrogenases efficiently convert electrical into chemical energy with simple and inexpensive iron oxide: (i) their catalytic centre is shielded inside the protein from poisoning contaminants that would irreversibly oxidize the iron oxide, and (ii) their “delivery chains” efficiently and fast drag away electrons and protons from their source. Thereby, redox enzymes prevent energy-rich electrons from wasting energy by recombining with the wrong partner.

What we want to do: A far reaching goal of the NANOSTACKS project is to implement aforementioned design principle into nano-printed nanostacks: (i) a catalytic layer with inexpensive FeO is shielded from molecules that would irreversibly oxidise it, and, therefore, can do without expensive platinum, and (ii) a gradient of redox centres pre-determines the electron’s path, and, thereby, reduces the time where energy-rich electrons would recombine with the “wrong” partners (Fig. 2).

However, in order to reach this far reaching goal, we first have to implement a new screening method that would allow us to print many different multi-material nanostacks, and screen them for nanoscale novel materials, e.g. conductors, insulators, diodes, LEDs, proton- or electron-conducting layers. Key elements of this screening method for novel nano-dimensioned materials are (i) a multi-material nano3D printer (KIT & SME PEPperPRINT), (more) (ii) to-be-printed materials including nanoparticles (commercial available materials, SME TECNAN & Lurederra Technology Centre), and (iii) microstructured acceptors that will help us to print materials to exactly defined x,y-coordinates (Univ. LEUVEN).