Efficient and Stable Photoelectrochemical Seawater Splitting with TiO2@g-C3N4 Nanorod Arrays Decorated by Co-Pi

Co-Pi decorated TiO 2 @graphitic carbon nitrides ( g -C 3 N 4 ) nanorod arrays (denoted as CCNRs) with different mass ratios of g -C 3 N 4 have been constructed on the FTO substrate through three processes, hydrothermal growth, chemical bath deposition and electrodeposition. First, TiO 2 nanorod arrays were grown onto a FTO substrate by a hydrothermal method. Second, g -C 3 N 4 was coated onto the TiO 2 nanorod arrays by immersing the above substrate with TiO 2 nanorod arrays into a solution of urea and then heated at higher temperature. In this procedure, the amount of the g -C 3 N 4 on the TiO 2 nanorod arrays can be controlled by tuning the concentration of the urea solution. At last, Co-Pi were decorated on the surface of the TiO 2 @ g -C 3 N 4 by electrodeposition. The as-prepared CCNRs were characterized by XRD, FESEM, TEM, XPS, UV–vis, and FTIR, respectively, which illustrated that Co-Pi moieties were successfully decorated on the hybrid TiO 2 @ g -C 3 N 4 nanorod arrays. Photoelectrochemical (PEC) measurements have demonstrated that the prepared CCNRs serve as an efficient and stable photoanode for PEC seawater splitting. The photocurrent density reaches 1.6 mA/cm 2 under 100 mW/cm 2 (AM1.5G) light illumination at 1.23 V (RHE). More significantly, the CCNRs photoanode is quite stable during seawater splitting and the performance remain undiminished even after 10 h continuous illumination. Finally, a systematical photocatalytic mechanism of the Co-Pi decorated TiO 2 @ g -C 3 N 4 was proposed, and it can be considered as potential explanation of enhanced PEC performance.