Department of Inorganic and Analytical Chemistry University of

Department of Inorganic and Analytical Chemistry, University of Geneva, Quai E. Ansermet 30, CH-1211 Geneva, Switzerland

Introduction Present Study Membrane Spiropyran (Sp) Sp Cation exchanger (K+R-) Lipophilic salt (ETH 500) In a supported liquid membrane Merocyanine (Mc) Mc form exhibits higher p. K a value than Sp (Chem. Commun. 48, 5662– 5664 (2012)) Sp used as light triggered ion exchange materials selective for Ca 2+, Na+, Cl(J. Am. Chem. Soc. 134, 16929– 16932 (2012)) Major Findings Scheme demonstrating the photocurrent generation 1)Artificial light-hervesting system based on a liquid polymeric membrane. 2)Proton gradient is generated acroos the membrane upon light illumination. 3)UV and Visible light cause the proton flux to different direction and alternating current is generated

Light-induced voltage and current due to a light-driven proton gradient within the spiropyran-doped polypropylene membrane. a, Representation of the flow cell used to measure the photocurrent generated by the light-harvesting membrane. b, Photocurrents generated when the membrane is placed in 0. 1 M HCl and illuminated with ultraviolet light on one side. c, Photocurrent generated with illumination by visible light (482+35 nm) on one side of the membrane. d, Observed open-circuit voltage when the membrane is illuminated with ultraviolet on one side and subsequently with visible on the other

Conversion efficiency for the light-harvesting system and Alternating current generation a, Current density characteristics for the light- arvesting cell under light illumination (10 Wcm 22) and in the dark. b, Corresponding power density–voltage relationship under light irradiation. Alternating photocurrent generation by the membrane in 0. 1 M HCl with alternating ultraviolet and visible light (ultraviolet for 2 s +off for 4 s + visible for 1 s + off for 4 s) illuminating one side of the membrane.

Conclusion a polymeric liquid membrane light-harvesting systemis presented that utilizes the photoswitching of spiropyran with ultraviolet and visible light. Currents of different signs are observed when the membrane is illuminated with ultraviolet or visible light and alternating current can be produced by applying alternatingultraviolet and visible light.

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Theoretical simulation to understand the current evolution a, Photocurrent evolution from numerical simulation showing the difference between ultraviolet irradiation on one side only (ringopening rate constant k 1. 1021. 1 s 21, ring-closing rate constant k 2. 1 s 21) and asymmetric illumination with ultraviolet and visible (k 1. 1021. 1 s 21, k 2. 1026 s 21). b, Experimental photocurrent generated when the membrane is illuminated with the light sequence indicated in the figure.

Influence of an interfering ion to the direction proton flux