ML and high-throughput screens find organic H2 photocatalysts
Screening 572 then 96 organic molecules under identical HER conditions, plus ML, uncovered unexpected molecular photocatalysts rivaling conjugated polymers.
Source
Combining machine learning and high-throughput experimentation to discover photocatalytically active organic molecules
What they did
Authors measured sacrificial photocatalytic hydrogen evolution for hundreds of laboratory-available aromatics under one solar-simulator protocol with Pt and triethylamine/methanol, then trained unsupervised and supervised ML models (including SOAP-KNN and MLP classifiers) and tested a 96-molecule blind set.
What they found
About 1% of the library matched polymer-level HERs; aryl carbonyls and triplet-related optoelectronic descriptors correlated with activity; an adaptive ML advisor found active catalysts faster than random sampling.
The limits
What it doesn't show
The screen is sacrificial HER with photodeposited Pt, not water-splitting without a hole scavenger, and the 668-molecule set is still a tiny slice of organic chemical space.
Key terms
- HER
- Hydrogen evolution rate from photocatalytic water reduction under the authors’ sacrificial conditions.
- Sacrificial agent
- Electron donor (here triethylamine/methanol) that supplies electrons so the photocatalyst can reduce protons.
- SOAP
- Smooth overlap of atomic positions, a local structural descriptor used in the KNN classifiers.
- TADF
- Thermally activated delayed fluorescence, a triplet-harvesting photophysical process noted for ID566.
- Blind-test set
- 96 extra molecules held out of the original 572-member library to test ML generalization.
Flashcards
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The experimental photocatalytic metric here is:
Common questions
How many molecules were measured in total?
668 (572 library plus 96 blind-test molecules).
What was the top molecular HER?
28.3 μmol h−1 (5660 μmol g−1 h−1) for ID153.
Which sacrificial agent worked best?
Trimethylamine among those tested.
What structural motif was common among high-activity molecules?
At least one aryl carbonyl (except ID566).
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