Stefan Bernhard
Professor Carnegie Mellon University
- Pittsburgh PA
Stefan Bernhard is interested in interconverting radiative and electrochemical energy through the use of transition metal complexes.
Biography
The Bernhard lab is interested in interconverting radiative and electrochemical energy through the use of transition metal complexes with electronically tunable architectures. That is, they study both the absorption of light to generate electrochemical potential (organic photovoltaics and artificial photosynthesis) as well as the emanation of light using electrical current (organic light emitting devices). The Bernhard lab is also deeply involved in the exploration of chiral luminophores (and chiral ensembles) that emit circularly polarized light. Their work in this area has produced cutting-edge tools for both the characterization and prediction of polarized luminescence. In each of the above areas, it is our aspiration to precisely understand and administer the interactions that control ensemble properties by establishing clear structure-activity relationships.
Areas of Expertise
Media Appearances
Designer catalyst with enzyme-like cavity splits water almost as fast as plants
Chemistry World online
2022-10-12
‘It is very hard to oxidise water,’ explains Stefan Bernhard, a renewable energy chemist at Carnegie Mellon University, US. ‘The process requires the transfer of four electrons and so needs a lot of electrochemical or photochemical energy. One of the particularly tricky aspects is ensuring that the catalyst isn’t just “burnt up” by these demanding conditions.’
Bernhard Designs Materials for Energy, Electronics of the Future
Carnegie Mellon University Mellon College of Science online
2020-09-04
Stefan Bernhard, Scott Institute Energy fellow and Carnegie Mellon University chemistry professor, conducts research on converting sunlight into fuel, which has been the driving force of his work since his undergraduate career.
Media
Industry Expertise
Accomplishments
Graduate Mentoring Award
2006
Princeton University
National Science Foundation CAREER Award
2005
Dreyfus New Faculty Award
2002
Education
Université de Fribourg, Switzerland
Ph.D.
Chemistry
1996
School of Engineering, Burgdorf, Switzerland
Diploma
Chemical Engineering
1988
University of Fribourg, Switzerland
Diploma
Chemistry
1993
Links
Articles
Synthesis and Structure of an Ion-Exchanged SrTiO3 Photocatalyst with Improved Reactivity for Hydrogen Evolution
Advanced Materials Interfaces2023
BaTiO3 heated in an excess of SrCl2 at 1150 °C converts to SrTiO3 through an ion exchange reaction. The SrTiO3 synthesized by ion exchange produces hydrogen from pH 7 water at a rate more than twice that of conventional SrTiO3 treated identically. The apparent quantum yield for hydrogen production in pure water of the ion exchanged SrTiO3 is 11.4% under 380 nm illumination.
Photogeneration of Hydrogen from Glycerol and Other Oxygenates Using Molecular Photocatalysts and In Situ Produced Nanoparticulate Cocatalysts
ACS Sustainable Chemistry & Engineering2022
This work describes a photocatalytic process using the oxidation of biorenewable alcohols as the electron/proton source for the photogeneration of hydrogen. The approach utilizes a molecular iridium photosensitizer (PS), an in situ synthesized Pd-containing colloid catalyst, and a redox shuttle (RS). By virtue of the high-throughput photoreactor utilized in this work, rapid reaction parameter screening for five donor species (oxalic acid, benzyl alcohol, isopropanol, ethanol, and glycerol) was undertaken, resulting in the identification of reaction conditions conducive to the formation of hydrogen from all species.
Identifying limitations in screening high-throughput photocatalytic bimetallic nanoparticles with machine-learned hydrogen adsorptions
Applied Catalysis B: Environmental2023
The Sabatier principle is of fundamental importance to computational catalyst discovery, saving researchers time and expense by predicting catalytic activity in silico at scale. However, as polycrystalline and nanoscale catalysts increasingly dominate industry, computational screening tools must be adapted to these uses. In this work, we demonstrate the effectiveness of computational adsorption energy screening in nanocatalysis by comparing a multisite adsorption energy prediction workflow against a large experimental dataset of hydrogen evolution activities over bimetallic nanoparticles.
Reinterpreting the Fate of Iridium(III) Photocatalysts─Screening a Combinatorial Library to Explore Light-Driven Side-Reactions
Journal of the American Chemical Society2022
Photoredox catalysts are primarily selected based on ground and excited state properties, but their activity is also intrinsically tied to the nature of their reduced (or oxidized) intermediates. Catalyst reactivity often necessitates an inherent instability, thus these intermediates represent a mechanistic turning point that affords either product formation or side-reactions. In this work, we explore the scope of a previously demonstrated side-reaction that partially saturates one pyridine ring of the ancillary ligand in heteroleptic iridium(III) complexes.
Ligand Enhanced Activity of In Situ Formed Nanoparticles for Photocatalytic Hydrogen Evolution
ChemCatChem2021
Hundreds of metal combinations and concentrations can be and have already been tested to determine promising hydrogen evolution catalysts. However, variables such as the formation of nanoparticles and the stability of those nanoparticles complicate interpretation of successful metal stoichiometries. Here, we report the addition of nanoparticle ligands is necessary to sustain hydrogen evolution in nanoparticle catalysts.
