Thylakoids embedded in the chloroplast of plant absorb solar energy and produce photosynthetic electrons (PEs) from water splitting during photosynthesis. PEs excited by absorbing light energy are transferred via electrical carriers in the thylakoid membrane and finally they are consumed to form NADPH. Recent studies have investigated to harvest these excited PEs from thylakoids more efficiently through various approaches such as physical modification of electrodes, tethering of multi-walled carbon nanotubes to thylakoids, or use of mediators. Although these researches contributed to improve the efficiency of PE harvesting, still further studies are needed to achieve practical uses of the photosynthesis-based energy. In this study, we propose that 2-dimensional (2D) ruthenium oxide (RuO₂) nanosheet-deposited electrodes can increase the amount of extracted PEs from thylakoids. With large surface area, 2D RuO₂ nanosheets have high electrical conductivity and capacity such that they do not only enhance PE extraction but they also increase electron storage. RuO₂ nanosheets were synthesized by following processes. First, layered NaRuO₂ was synthesized by a solid state reaction, and then Na₂S₂O₈ solution was added to remove excess Na ions. 1 M HCl solution was treated for protonating Na_0.2RuO₂ before RuO₂ exfoliated to RuO₂ nanosheets by additional protonating with tetrabutylammonuim. To purify thylakoids, spinach leaves were blended, filtered and centrifugated to extract chloroplasts which contain thylakoids within their membrane. Then, the chloroplasts were osmotically shocked to destroy chloroplast membranes, and density gradient centrifugation was performed to obtain pure thylakoids. For electrode modification with RuO₂, RuO₂ nanosheets were deposited on Au electrodes by two different methods: drop casting and electrophoresis. 10 and 50 μL of RuO₂ solution with 2 mg/mL concentration was dropped on 1 cm² Au electrode such that 0.02 and 0.1 mg/cm² of RuO₂ nanosheets were deposited on the electrodes. For electrophoretic deposition, Au electrodes were immersed in an acetone solution with 0.01 mg/mL concentration of RuO₂. Because the zeta potential of RuO₂ nanosheets is negative, the Au electrode was biased with 20 V in order to deposit RuO₂ nanosheets on electrode. The thickness of RuO₂ nanosheet film was controlled with deposition time. RuO₂ was deposited 70 ~ 90 nm during 30 sec and 1~ 1.6 μm during 300 sec. For PEs extraction, 30 μL of thylakoid solution with 3 mg/mL chlorophyll concentration was dropped and dried on each electrode including bare Au electrodes as a control. Bias potential was maintained at 400 mV verses Ag/AgCl and Pt mesh was used as a counter electrode. Photosynthetic currents evidently increased for Au electrodes modified by RuO₂ nanosheets. The PE currents from electrodes coated with RuO₂ nanosheets were more than 4 times greater than that of bare Au electrodes. To be specific, in case of 0.02 mg/cm² drop-cast RuO₂ electrodes and electrophoretically-deposited RuO₂ samples, PE currents were up to 500 nA/cm², while PE currents from 0.1 mg/cm² drop-cast RuO₂ electrodes were 350 nA/cm². Also, electrophoretically deposited RuO₂ films were stable, while the drop cast RuO₂ films were detached after several hours of solution immersion for electrochemical measurement.