Electrocatalytic CO2 Reduction at Pyridine Functionalized Au Nanoparticles Supported by NanoCOT Electrode

CO2 reduction reaction (CO2RR) is a promising technique for mitigating global warming and storing renewable energy if it can be obtained with a highly selective, efficient, and durable electrocatalyst. Here, we report CO2RR catalyzed by Au nanoparticles (NPs) stabilized by pyridines and pyrimidines (e.g., 2-mercaptopyridine (2Mpy), 4-mercaptopyridine (4Mpy), and 2-mercaptopyrimidine (2Mpym)) on a nanostructured carbon-doped TiO2 nanowire (NanoCOT) electrode, which has been previously reported by our team for electrocatalytic water oxidation. An online gas chromatography (GC) set-up with improved gaseous product sensitivity with real-time pressure monitoring is used to quantify CO and hydrogen products from the Au NP-modified NanoCOT electrode. High CO selectivity is observed at Au-2Mpy coated NanoCOT electrode. CO2 reduction products are not observed at bare NanoCOT suggesting CO2 is reduced at the Au nanoparticle sites of the electrode. Moreover, CH3OH is not detected at the Au-Mpy/Mpym NPs during rotating ring disk electrode (RRDE) analysis which implies pyridine attached to the Au NPs has no catalytic effects on CO2RR as claimed by others in the literature. A durable complete H-cell using a NanoCOT anode and Au NP-NanoCOT cathode electrodes is assembled for complete water splitting, CO2RR, and stability test.

Automated summary

In this study, CO2 reduction reaction (CO2RR) catalyzed by Au nanoparticles (NPs) was reported. The Au NPs exhibited high selectivity in reducing CO2 to CO and hydrogen gas. A novel nanostructured electrode was used and the Au-2Mpy coated electrode showed high CO selectivity. The results also suggested that the pyridine attached to the Au NPs had no catalytic effects on CO2RR.