Crucial role of sustainable liquid junction potential for solar-to-carbon monoxide conversion by a photovoltaic photoelectrochemical system

Abstract

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.

Solar-driven CO2 to CO reduction utilizing H2O as an electron donor by earth-abundant Mn–bipyridine complex and Ni-modified Fe-oxyhydroxide catalysts activated in a single-compartment reactor

“…The product ratios were almost the same as those observed for the poly-Si cells. Photoelectrochemical CO 2 reduction to CO using the same light absorber has been reported by Sugano et al, 24 where the system was composed of an Au nanoparticle cathode and a photoanode that combined a 3jn-a-Si cell and a CoO x catalyst. A two-compartment reactor separated by an anion exchange membrane was used for the wired photovoltaic-photoelectrochemical cell system.…”

Recent Advances in Photoelectrochemical Applications of Silicon Materials for Solar‐to‐Chemicals Conversion

“…Additionally, silicon materials were used as photoanodes to drive water oxidation to generate electrons and protons required in the CO 2 RR on the cathode side, the process for which was regarded as the indirect PEC CO 2 RR. For example, a triple‐junction a‐Si:H PV cell with a CoO x catalyst, and a c‐Si heterojunction solar cell with Ni foam catalyst, were reported to be OER photoanodes for driving the cathodic CO 2 RR ,. In these cases, the efficiencies and products of the CO 2 RR strongly depended on the cathode catalyst used.…”

Design of an artificial photosynthetic system for production of alcohols in high concentration from CO2

“…Figure 5b shows that the crossover current density is equal to the ethanol current density until the onset of phase separation occurs at the catalyst-to-membrane (Cu cathode-to-Nafion membrane) area ratio of 18.46, after which the crossover current density rapidly decreases with further increasing catalyst-to-membrane area ratio, since the ethanol in the electrolyte is already at the saturation limit. The ohmic loss across the membrane increases linearly with increasing catalyst-to-membrane area ratio, and for the area ratio of 18.46 the crossover current density is equal to 0.6 mA/cm 2 , which means that the net rate of ethanol formation will be 0.85 -0.60 = 0.25 mA cm -2 ; however, the ohmic loss across the membrane will only be 20 mV. The crossover current density could be reduced from 0.6 mA cm -2 to 0.1 mA cm -2 by decreasing the membrane ethanol permeability by six fold relative to Nafion 117, and in this case, the net ethanol current density will become 0.85 -0.1 = 0.75 mA cm -2 .…”

“…10,27 A photo/electrochemical cell consisting of IrO2 anode and Cu cathode separated by Nafion 117 can be operated at -1.1 vs RHE to generate such current densities in Cs2CO3 electrolyte. 20 However, as noted above, rate of ethanol generation is well below the threshold current density to form a microemulsion in a 13 wt% CsCO3 solution (10.6 mA/cm 2 ), and all of the ethanol produced will cross over to the anolyte compartment and be consumed. One way to circumvent this situation is to increase the ratio of catalyst-to-membrane areas well above 1.0.…”

“…Solar-driven photo-electrochemical CO2 reduction (CO2R) devices based on various catalysts and light absorbers with varying levels of integration have been demonstrated experimentally, [1][2][3][4][5] and investigated theoretically in detail. 6,7 Such devices typically operate at near-neutral pH using bicarbonate electrolyte, cation-or anionexchange membrane, and pure CO2 feed.…”