Enhanced Photoelectrochemical Performance from Rationally Designed Anatase/Rutile TiO₂ Heterostructures

Abstract

In a photoelectrochemical (PEC) cell for water splitting, the critical issue is charge separation and transport, which is usually completed by designing semiconductor heterojunctions. TiO2 anatase-rutile mixed junctions could largely improve photocatalytic properties, but impairs PEC water splitting performance. We designed and prepared two types of TiO2 heterostructures with the anatase thin film and rutile nanowire phases organized in different sequences. The two types of heterostructures were used as PEC photoanodes for water splitting and demonstrated completely opposite results. Rutile nanowires on anatase film demonstrated enhanced photocurrent density and onset potential, whereas strong negative performance was obtained from anatase film on rutile nanowire structures. The mechanism was investigated by photoresponse, light absorption and reflectance, and electrochemical impedance spectra. This work revealed the significant role of phase sequence in performance gain of anatase-rutile TiO2 heterostructured PEC photoanodes.

Black Si-doped TiO2 nanotube photoanode for high-efficiency photoelectrochemical water splitting

“…29 This indicated that Sidoping could suppress the phase transformation from anatase to rutile, the result was in agreement with previous report.…”

“…The reversible hydrogen potential V RHE could be obtained according to the equation of V RHE ¼ V Ag/AgCl + 0.059pH + 0.199, 29 where V Ag/AgCl represents the applied bias, and pH value is 13.6 for the KOH electrolyte. As shown in Fig.…”

Structure and Band Alignment Engineering of CdS/TiO2/Bi2WO6 Trilayer Nanoflake Array for Efficient Photoelectrochemical Water Splitting

“…Figure S15 shows the room-temperature photoluminescence (PL) spectra, which demonstrates that the CdS/TiO 2 /Bi 2 WO 6 displays the lower intensity than CdS/Bi 2 WO 6 , indicating the appropriate thick TiO 2 layer can reduce the recombination of photo-generated electron-hole pairs, [43] which is in accordance with the separation efficiency result. The carrier density can be calculated through the following equation: [44] Typically, the slope of plot is related to the type of semiconductor and carrier concentration.…”

Ordered Single-Crystalline Anatase TiO2Nanorod Clusters Planted on Graphene for Fast Charge Transfer in Photoelectrochemical Solar Cells

“…Figure a shows the Mott–Schottky (M–S) plot of 1/ C 2 as a function of the applied potential, from which positive slopes were observed, suggesting n‐type semiconductors. [2b] Furthermore, the carrier density ( N D ) of the samples could be calculated from Figure a according to the following equationwhere e is the electron charge (1.6 × 10 −19 C), ε 0 is the permittivity of the free space (8.86 × 10 −12 F m −1 ), ε is the dielectric constant of the semiconductor (48 for anatase TiO 2 ), and C is the capacitance. In our case, the N D value of rGO/ATRCs reaches as high as 4.3 × 10 19 cm −3 , which is much higher than that of common rGO/TNPs (7.15 × 10 18 cm −3 ).…”

“…Consequently, the higher N D of rGO/ATRCs signifies lesser trap sites than that in rGO/TNPs for favorable electron transfer, thus leading to enhanced photovoltaic performance. [2a]…”