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

Abstract

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. Firstly, TiO 2 nanorod arrays were grown onto a FTO substrate by a hydrothermal method. Secondly, 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 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 ten hours 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. .7 eV 35 , has attracted more and more attentions for its inherent chemical and thermal stability 36, 37 . Unlike transitional metal oxides and sulfide semiconductor photocatalysts, g-C 3 N 4 behaves very stable performance in acid or alkaline electrolytes ascribing to strong covalent bonds between carbon and nitride atoms in its structure 38 . However, applications of pure g-C 3 N 4 are limited largely because of its low quantum efficiency and high electron-hole recombination rate 39 .Therefore, it lays a large space to explore and construct novel composite materials to remedy these deficiencies of pure g-C 3 N 4 .Herein, we combined TiO 2 and g-C 3 N 4 to fabricate TiO 2 @g-C 3 N 4 nanorod arrays 40 with different mass ratios of g-C 3 N 4 via hydrothermal growth and chemical bath deposition. Moreover, the composite nanorod arrays were decorated with Co-Pi particles 41-43 to offset the inadequacy of g-C 3 N 4 44 . To the best of our knowledge, this is the first report upon semiconductor nanorod arrays modified with tunable g-C 3 N 4 mass ratio. As reported, Co-Pi decorated TiO 2 @g-C 3 N 4 nanorod arrays (CCNRs) used for photoelectrode within PEC cells are still unexplored. More importantly, the results in this work have proved that the composited nanorod arrays as photoelectrodes exhibit very efficient and stable performances for PEC seawater splitting.

First row transition metal catalysts for solar-driven water oxidation produced by electrodeposition

“…This enhanced performance of photo-electrodeposited films was attributed to more uniform distribution of the catalyst across the surface of the semiconductor, in a similar manner to that previously reported by Gamelin. [95][96][97] 106 The photocatalytic performance of these electrodes for the OER under 1 Sun was found to be about 30% better (at a bias of +1.5 V vs. RHE) than that of undecorated TiO 2 -gC 3 N 4 substrates, which in turn showed about 3 times the activity of TiO 2 under the same conditions. Ni-oxide electrodeposits have also been generated on semiconductor substrates for use as photoanodes for the OER.…”

Photoelectrochemical Immunosensor for Detection of Carcinoembryonic Antigen Based on 2D TiO2 Nanosheets and Carboxylated Graphitic Carbon Nitride

“…Thus, owing to the proper band level between g-C 3 N 4 and TiO 2 , g-C 3 N 4 and TiO 2 are combined together leading to the easy separation of the photo-generated electron and hole. Although there are some references about the combination of g-C 3 N 4 and TiO 2 , the morphology of TiO 2 is maily focused on nanorod1014, nanoparticles11 and nanotube151617.…”

Fabrication and photoelectrochemical properties of silicon nanowires/g-C3N4 core/shell arrays

“…Comparing the XRD pattern of Si NWs/g-C 3 N 4 and the Si NWs, it can be concluded that the diffraction peaks at 38.5 • and 44.7 • of the Si NWs/g-C 3 N 4 sample can be attributed to the (111) and (200) crystal planes of Si. This result might be ascribed to the fact that the amount of g-C 3 N 4 was very small and well dispersed onto the surface of the Si NWs [20].…”

“…Various strategies, such as morphology modification, elemental doping, and copolymerization are subsequently applied to improve the photocatalytic performance of g-C 3 N 4 [16][17][18]. More recently, combining g-C 3 N 4 with other semiconductors, such as ZnO, TiO 2 , CuInS 2 , Bi 5 O 7 I, InVO 4 , to form a photoelectrochemical (PEC) heterogeneous electrode for water splitting has been considered an effective way to improve its photocatalytic activity [19][20][21][22][23][24][25]. However, these photoelectrodes also suffer from insufficient absorption of solar energy and poor surface area, which may restrict their practical applications.…”