An efficient strategy to improve photoelectrochemical performance of TiO₂ nanowire arrays by optimization electrolytes

Optimization of photoelectrochemical (PEC) performance for electrode is very important to efficiently utilize solar energy in the form of chemical energy. The aim of this study is to optimize the PEC performance of TiO₂ nanowire array electrodes via the optimization of Na₂SO₃ and Na₂SO₄ electrolytes. The electrode shows significant improvement for the PEC performance in Na₂SO₃ electrolyte with a photocurrent density of 0.8 mA/cm², which is 5 times higher than that in Na₂SO₄ electrolyte. The incident photon-to-current conversion efficiency obtained in Na₂SO₃ electrolyte is 14.7% at λ = 390 nm, which is 2.6 times higher than that in Na₂SO₄ electrolyte. The Mott-Schottky and electrochemical impedance spectroscopy measurements experimentally show that the improved PEC performance is attributed to the efficient separation of photo-generated electrons and holes induced by the consumption of holes by ${\mathrm{S}\mathrm{O}}_3^{2-}$. The results of this study provide a promising strategy to improve the PEC performance of electrode by choosing the optimal electrolyte.