BALÁZS ENDRŐDI

Electrochemical reduction of carbon-dioxide is a possible route to turn a harmful waste into valuable raw chemicals, such as carbon monoxide, methane or formic acid. In the past decades the research activity in this field intensified significantly, in parallel with the concern of Society with regards to the increasing carbon dioxide concentration in the atmosphere.
In our research we work towards the industrialization of this process. This includes the constant development of our custom-designed electrolyzer cells, the application of newly developed catalysts and other cell components, and investigating the effect of different operating conditions. We aim to achieve long-term, stable operation of these cells at high CO₂ reduction rate, selectivity, conversion efficiency and with high energy efficiency.
References

1. B. Endrődi, A. Samu, E. Kecsenovity, T. Halmágyi, D. Sebők and C. Janáky: Operando cathode activation with alkali metal cations for high current density operation of water-fed zero-gap carbon dioxide electrolysers, Nature Energy 6, 439–448 (2021)
2. B. Endrődi, E. Kecsenovity, A. Samu, F. Darvas, R. V. Jones, V. Török, A. Danyi, and C. Janáky: Multilayer Electrolyzer Stack Converts Carbon Dioxide to Gas Products at High Pressure with High Efficiency, ACS Energy Lett. 4, 7, 1770–1777 (2019)
3. B. Endrődi, G. Bencsik, F. Darvas, R. Jones, K. Rajeshwar, C. Janáky: Continuous-flow electroreduction of carbon dioxide, Progress in Energy and Combustion Science 62, 133-154 (2017)

Electrochemical techniques offer a very high level of control over catalyst synthesis on conducting substrates. Tuning either the electrode potential or the current density, the phase composition, particle size, electrode coverage etc. can be easily tuned. Furthermore, the amount of the electrodeposited material is simply controlled by the charge passed, which is directly related to the reaction time. Importantly, the deposition can be stopped, slowed down or varied in many ways during the experiments - this is a truly unique feature of electrochemistry.
In our work we aim to prepare photocatalyst/electrocatalyst coatings on conducting substrates, such as metal/conducting glass sheets, different nanostructures or carbon fiber papers. This work often necessitates designing new cells - this is done through CAD modelling and 3D printing. The deposited catalysts are thoroughly characterized with a wide variety of techniques (including spectroscopis, microscopic and other methods), which provides insight to the modern materials science for the students/researchers.
References

1. B. Endrődi, E. Kecsenovity, K. Rajeshwar, C. Janáky: One-Step Electrodeposition of Nanocrystalline TiO₂ Films with Enhanced Photoelectrochemical Performance and Charge Storage, ACS Appl. Energy Mater. 1, 2, 851–858 (2018)
2. B. Endrődi, O. Diaz-Morales, U. Mattinen, Maria Cuartero, A. K. Padinjarethil, N. Simic, M. Wildlock, G. A. Crespo, A. Cornell: Selective electrochemical hydrogen evolution on cerium oxide protected catalyst surfaces, Electrochimica Acta, 341, 136022 (2020)

Novel catalysts, electrode assemblies, and cell configurations are all necessary to achieve economically appealing performance of different electrolyzer technologies, such as CO₂, CO or N₂ reduction. While the majority of the scientific community is focusing on catalyst materials and reaction mechanisms, less emphasis has been devoted to cell structures and components.
We constantly develop and upscale our electrolyzer cells. We mostly focus on fuel-cell like, zero-gap cells. In these structures the two electrodes are sandwiched together through a membrane. The intimate connection between the cell components ensures low cell resistance, but it also enhances the effect, and even more importantly the limitations of the individual parts. We therefore constantly develop new analytical and electrochemical methods to better understand the origin of the reaction rate, energy efficiency and stability limitations. Widening a certain bottle-neck always points to the next one. This leads to an always fascinating (occasionally frustrating), step-like progress of our research.

1. B. Endrődi, E. Kecsenovity, A. Samu, T. Halmágyi, S. Rojas-Carbonell, L. Wang, Y. Yan, C. Janáky: High carbonate ion conductance of a robust PiperION membrane allows industrial current density and conversion in a zero-gap carbon dioxide electrolyzer cell, Energy Environ. Sci., 13, 4098-4105 (2020)