Imidazolium ion-terminated self-assembled monolayer (SAM)-modified electrodes achieve CO2 conversion while suppressing hydrogen evolution. Immobile imidazolium ion on gold (Au) electrodes reduce CO2 at low overpotential. The distance between electrode and imidazolium ion separated by alkane thiol affects CO2 reduction activity. CO2 reduction current depends on the tunnel current rate. Although the product of CO2 reduction at the bare Au electrode is CO, SAM-modified electrodes produce ethylene glycol in aqueous electrolyte solution without CO evolution. The faradaic efficiency reached a maximum of 87%. CO2 reduction at SAM-modified electrodes is unaffected by reduction activity of Au electrode. This phenomenon shows that the reaction field of CO2 reduction is not the electrode surface but the imidazolium ion monolayer.

Solar energy conversion to carbon monoxide (CO) is carried out using a wired photovoltaic photoelectrochemical (PV PEC) system under simulated solar light irradiation. The PV PEC system promotes CO generation from carbon dioxide and water with approximately 2.0% solar-to-CO conversion efficiency (h CO ) for 2 h. This is achieved via contributions from electrolyte conditions, which generate a sustainable liquid junction potential, in addition to the combination of efficient visible light absorption by a triple-junction amorphous silicon PV cell with high electrode activities with low overpotentials. Estimations of energy conversion efficiency based on the electrochemical properties of the PV cell and electrodes exhibit that the liquid junction potential makes a huge contribution to h CO .Moreover, the liquid junction potential created by bubbling two kinds of carrier gases produces sustainable chemical bias. This system may contribute to new strategies for the development of sustainable artificial photosynthesis.

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