Crucial role of sustainable liquid junction potential for solar-to-carbon monoxide conversion by a photovoltaic photoelectrochemical system†
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 (ηCO) 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 ηCO. 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.