The “Midas Touch” Transformation of TiO2 Nanowire Arrays during Visible Light Photoelectrochemical Performance by Carbon/Nitrogen Coimplantation

Abstract Titanium dioxide is a promising photoanode material for water oxidation, but it is substantially limited by its poor efficiency in the visible light range. Herein, an innovative carbon/nitrogen coimplantation method is utilized to realize the “Midas touch” transformation of TiO 2 nanowire (NW) arrays for photoelectrochemical (PEC) water splitting in visible light. These modified golden–yellow rutile TiO 2 NW arrays (C/N‐TiO 2 ) exhibit remarkably enhanced absorption in visible light regions and more efficient charge separation and transfer. As a result, the photocurrent density of carbon/nitrogen co‐implanted TiO 2 under visible light (>420 nm) can reach 0.76 mA cm −2 , which far exceeds the value of 3 µA cm −2 seen for pristine TiO 2 nanowire arrays at 0.8 V versus Ag/AgCl. An incident photon to electron conversion efficiency of ≈14.8% is achieved at 450 nm on C/N‐TiO 2 without any other cocatalysts. The ion implantation doping approach, combined with codoping strategies, is proved to be an effective strategy for enhancing the photoelectrochemical conversion and can enable further improvement of the PEC water‐splitting performance of many other semiconductor photoelectrodes.