CRC 1633 Pushing Electrons with Protons

The CRC 1633 aims at facilitating new strategies for redox catalysis, as key enabling methodology for sustainable chemical synthesis and energy conversion based on renewable and chemically inert feedstock (CO2, O2, H2O, N2, biomass). For this purpose, the projects focus on a physicochemical phenomenon that controls the energetics and selectivity of redox transformations of these chemically diverse and unreactive substrates: The thermochemical and/or kinetic coupling of proton and electron transfer, proton-coupled electron transfer (PCET).
As the central paradigm of the CRC, advancing the fundamental understanding of PCET provides unifying strategies across the traditional branches of catalysis (homogeneous, enzymatic, heterogeneous) towards energy-efficient redox transformations.

The CRC therefore aims at

• expanding concepts for (photo/electro)catalysis from redox-based to PCET-based strategies,
• advancing PCET models for key species relevant to catalysis,
• connecting PCET models with chemical and electronic structure descriptors of active sites,
• controlling PCET mechanisms with modular strategies for synthesis, and
• utilizing nuclear quantum effects (hydrogen tunneling) for selectivity control.

For this purpose, the projects develop advanced synthetic, spectroscopic, microscopic, electrochemical, and quantum-chemical methods to comprehensively cover the energy regimes, length scales, and time scales of PCET. They are applied towards the targeted redox transformations by focusing on selected PCET-active key molecular species and surface sites for oxidative and reductive catalysis, i.e., (doped) oxide semiconductors, as well as synthetic and biological oxo, nitrido and hydrido species. Close collaborations between the projects are organized in two dimensions:

(a) Within the traditional disciplines, the Project Groups (A: Molecular PCET, B: Biological PCET, C: Interfacial PCET) intend close the ‘utilization gap’ between predictive modelling of ground and excited state (multi-)PCET mechanisms and the utilization for PCET-driven (photo/electro)catalytic protocol development.

(b) The Working Groups (I: The PCET Site, II: Enabling Catalysis, III: Beyond Catalyst Design) aim at closing the ‘modelling gap’ across the disciplines by joint development and transfer of PCET models. All working groups evaluate nine physicochemical phenomena as control strategies for the interaction of local PECT sites with the local environment, i.e., proton tunneling, electron/spin dynamics, reorganization energies, hydrogen bonding, electron de-/localization, structural reorganization, proton supply, electric field effects, and ionic auxiliaries.