Cathode Surface pH Modulates Multicarbon Product Selectivity during the Electrochemical Conversion of CO<sub>2</sub> Capture Solutions
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Bibliographic record
Abstract
The electrolysis of (bi)carbonate solutions can upgrade captured carbon dioxide (CO 2 ) into chemicals and fuels. This style of electrolysis relies on a pH swing to release the CO 2 from the sorbent. Here, we report a bicarbonate electrolyzer equipped with an operando Raman spectroscopic probe that can measure the pH, at or near the cathode surface, as a function of current density. We correlate this cathode surface pH to the selectivity of the CO 2 reduction reaction products when electrolyzing (bi)carbonate, a CO 2 capture solution, set at different pH values. Our results show that C 2 products (C 2 H 5 OH) are favored over C 1 products (CO, CH 4, HCOO – ) when the pH at the cathode surface is high. This trend is consistent with the literature. However, at higher current densities and where the surface pH is highest, C 2 product formation is actually less favored. This outcome is because less CO 2 reactant is available for C−C coupling events. Consequently, the highest Faradaic efficiency for C 2 product formation (22%) occurred at the lowest current density measured (100 mA cm −2 ).
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
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Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it