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Recently,there has been a strong requirement for more powerful renewable portable power sources,which could be used in personal electronic devices.MFCs are considered a good candidate for these purposes.The energy density of fuel cells,which use external hydrogen fuel,is higher compared to existing batteries.However,external fuel causes difficulties when making portable MFC devices.To solve this problem,we propose to combine a fuel generation system with an MFC device to create a closed self-recharging fuel cell system based on hydrogen/oxygen fuel-making,through photocatalytic water splitting for autonomous power generation with effectively utilizing specific properties of micro/nano fluidics (See Fig.1.).Here,we report on the development of water splitting and the gas separation microfluidic device driven by the solar light energy for internal H2 and O2 generation with following consideration to combine the proposed system with the micro-fuel cell device.Firstly,we proposed two-dimensional nano-channels made in fused silica plate for efficient proton (H+) transport and separation.Series of experiments have been performed in our previous work to verify the H+ diffusion rate in extended nano-channels.The maximum value of H+ diffusion coefficient was detected when the nano-channels size decreased to 180 nm,and the result was~4.5 times higher in comparison with the bulk value1.Next,a photocatalytic water splitting system was developed2 and realized directly in a microfluidic chip made in fused silica plate,with the TiO2 nanostructured photoanode,Pt cathode,nano-channels array as the H+ transfer system and hydrophobic modified micro-channels as the gas-liquid separation system integrated in one microfluidic chip (Fig.2),and the working principle was confirmed.The results of the H2/O2 generation and separation are shown in Fig.3(a).Under solar light irradiation we observed the H2/O2 generation and separation,followed by the formation of H2 and O2 bubbles on the surfaces of Pt cathode and TiO2 photoanode,respectively.When the bubbles reached the appropriate size,they separated into hydrophobic channels due to Laplace pressure.The photocurrent was recorded in order to confirm the stability of our device during water splitting process.After 40 seconds of illumination,the photocurrent value started to periodically sweep due to the gases generation and separation (Fig.3(b)),which can be explained as follows: when the generated gases bubbles cover the electrodes they interfere the reaction,which results in the photocurrent decreasing.When the bubbles were removed from the electrode,the photocurrent increased again.The incident photon to current efficiency was also measured under the UV region and the maximum value ~48 % was reached.Also,we evaluated the generated gas by GC-MS to verify the H2/O2 separation and measured the generation rate of generated gases in the microfluidic chip.The results are shown in Fig.3(c).In summary,we have established the fundamentals of the light-driven micro fuel cell fabrication and verified the fuel generation and the gas liquid separation processes in the proposed microfluidic device.Presently,our efforts focus on developing and integrating more efficient photoanodes to improve the efficiency of the proposed device.