A microfluidic all-vanadium photoelectrochemical cell with multi-nanostructured TiO2 photoanode

All-vanadium photoelectrochemical cell possesses the inherent merits of both the all-vanadium redox flow battery and the solar energy utilization, which can directly store the solar energy in the form of the chemical energy. A promising design of the photoelectrochemical cell should provide large active surface area and ensure efficient transport of reactants, photons and charge carriers. To meet the above-mentioned requirements, a microfluidic all-vanadium photoelectrochemical cell with a multi-nanostructured TiO2 photoanode consisting of the interwoven nanotube bundles and the interspersed nanorods and nanoparticles, is proposed in this work for enhancing the solar energy storage. The miniaturization design can intensify the photon and mass transport because of the intrinsic large specific surface area, while the multi-nanostructured photoanode can offer more active surface area and plentiful pore structure, which can also enhance the photon and mass transport and avail the light scattering to deplete the photons. Such synergistic effect is able to promote the photoelectrochemical reaction efficiency. Experimental results show that the proposed photoelectrochemical cell exhibits excellent photoresponse and operation stability. Under each operation conditions, compared to conventional TiO2 nanoparticles stacked photoanode, the proposed photoanode can remarkably improve the vanadium ion conversion rate, demonstrating its promising potential in real applications.