Solar energy conversion and storage: Rhodamine B - Fructose photogalvanic cell Pooran Koli * , Urvashi Sharma, K.M. Gangotri Department of Chemistry, Jai Narain Vyas University, Jodhpur 342033, Rajasthan, India article info Article history: Received 29 September 2010 Accepted 14 June 2011 Available online 13 July 2011 Keywords: Fructose Rhodamine B Storage capacity Photogalvanic cell abstract Photogalvanic cells are photoelectrochemical cells chargeable in light for solar energy conversion and storage. They may be energy source for the future, if their electrical performance is increased. In this study, the Rhodamine B dye as photo sensitizer, Fructose as reductant and NaOH as alkaline medium has been used to enhance electrical performance of the cell. The observed cell performance is radically high. The observed cell performance in terms of maximum potential, maximum photocurrent, short-circuit current, power at power point, conversion efficiency and storage capacity in terms of half change time is 1071 mV, 1049 mA, 972 mA, 244.02 mW, 7.58% and 3.6 h, respectively. It is concluded that Rhodamine B - Fructose based cells have radically enhanced performance. It is also viewed that the Rhodamine B - Fructose based photogalvanic cells, with additional advantage of low cost and storage capacity, can give electrical output comparable to that for commercially used power storage property lacking photovoltaic cells. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Solar energy is a cheap, clean, abundant and freely available renewable non-conventional source for power generation. Photo- galvanic cell technique provides a promising and unexplored method for solar power generation and storage. Photogalvanic cell is a photoelectrochemical device involving ions as mobile charges moving in solution through diffusion process. In this cell, the solution is absorber phase contacted by two electrodes with different selectivity to the redox reaction. The current or voltage changes results from photo chemically generated changes in the relative concentrations of reactants in a solution phase redox couple. Alternatively, it can be said that in a photogalvanic cell, a dye in solution is photo excited to energy rich product which may lose energy electrochemically to generate electricity with inherent storage capacity. The inherent storage makes them superior to photovoltaic cells. There is no consumption of chemicals during charging and de-charging of these solar cells. First of all, Rideal and Williams [1] observed the photogalvanic effect during the action of light on the ferrous iodineeiodide equilibrium, which later on was systematically investigated by Rabinowitch [2,3] in Fe (II)-Thionine system. Rabinowitch sug- gested that the photogalvanic effect might be used to convert sunlight into electricity. To explore this suggestion, some photo- galvanic cells using the iron-thionine system as the photosensitive fluid were tested [4]. The observed maximum power conversion efficiency was 3  10 4 per cent. The principal reason for the low efficiency was shown to be polarization of the polished platinum electrodes and rapid loss of the photochemical activity of the dye. Coating the electrodes with platinum black reduced polarization sufficiently. In principle, it appeared possible to make further increases in efficiency by increasing electrode area and decreasing the electrolyte resistance. The maximum power conversion efficiency [5] that could be achieved from a photogalvanic cell is between 5 and 9%. Photogalvanic cells based on Chlorophyll-a (Chl-a) plated Pt electrode and Chl-a free Pt electrode separated by a salt bridge [6], aqueous ferric bromide [7], ruthenium complex of dye [8e10], [Cr 2 O 2 S 2 (1-Pipdtc) 2 (H 2 O) 2 ] in a Honda Cell [11], and micro emul- sions with micellar solution [12] have also been studied. Gangotri and Pramila [13] have presented principles of photogalvanic cell containing NaLS, mannitol (reductant) and safranine (photo sensitizer) in which compounds are broken up by sunlight into electrochemically charged fragments which usually recombine instantaneously if relieved of their electrical charges. In beginning, photogalvanics emphasized on coated Pt electrode with Fe 2þ as reducing agent. Later on, the researcher started using non-coated Pt electrode with saturated calomel electrode, dyes like methylene blue [14,15], azure-B [16], azure-A [17], fluoroscein [18], toluidine blue [19], malachite Green [20], etc., organic reductants like mannitol [21], oxalic acid [22],ethylene diamine tetraacetic acid [23], etc. and surfactants like sodium lauryl sulfate (NaLS) [24,25],Tween-80 [26], etc. * Corresponding author. Tel./fax: þ91 291 2614162. E-mail address: poorankoli@rediffmail.com (P. Koli). Contents lists available at ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene 0960-1481/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.renene.2011.06.022 Renewable Energy 37 (2012) 250e258