Tunable Photo‐Electrochemistry of Patterned TiO₂/BDD Heterojunctions

Abstract

Heterojunctions are especially attractive for photo‐electrocatalytic applications if both high‐performance photo and electrocatalysts are employed for their construction. Herein, a p–n heterojunction is synthesized using uniform patterns of p‐type boron doped diamond (BDD) and an n‐type anatase TiO2 film. The exposure ratios of the BDD patterns are varied to tune the photo‐electrocatalytic abilities of this heterojunction. A heterojunction with a BDD exposure ratio of 20% exhibits a photocurrent density of 0.63 mA cm−2, which is 2.86‐fold higher than that obtained on a BDD film and 1.91‐fold higher than that obtained on a TiO2 film coated on a BDD film. It completely degrades methyl orange within 4 h, following the application of a 2.5 V bias potential, while the degradation efficiency on the BDD film and the TiO2 film is 56% and 45%, respectively. As confirmed by electron spin resonance spectroscopy, an accelerated production rate of •OH radicals is realized on this heterojunction. It originates from a synergistic effect between the BDD patterns that act as an ultra‐microelectrode array with a TiO2/BDD p–n heterojunction as well as facilitated charge separation in a lateral direction. This TiO2/BDD patterned heterojunction is thus promising as a new photo‐electrocatalyst for various catalytic applications.

Layer‐by‐Layer Electrodeposition of FTO/TiO2/CuxO/CeO2 (1 <x< 2) Photocatalysts with High Peroxidase‐Like Activity by Greatly Enhanced Singlet Oxygen Generation

“…The similar phenomenon has been observed in FTO/TiO 2 /Cu x O that the initial morphology of Cu 2 O became significantly disordered after etching, and meanwhile the product of Cu x O began to cover the whole surface rather than just the edges of TiO 2 nanosheets by using NH 3 • H 2 O solely (Figure 1c). [ 40,41 ] Besides, the color of the FTO slide was changed from yellow (FTO/TiO 2 /Cu 2 O) to gray the same as the typical color of bulk CuO (Figure S1d, Supporting Information). But in situ etching occurred on the Cu 2 O surface in the presence of NH 3 • H 2 O and Ce(NO 3 ) 3 for FTO/TiO 2 /Cu x O/CeO 2 (Figure 1d) in good agreement with the morphology evolution in the previous reports, [ 15,38 ] as well reflected by the weakened intensity of the two characteristic XRD peaks of Cu 2 O in FTO/TiO 2 /Cu x O and FTO/TiO 2 /Cu x O/CeO 2 (Figures S3 and S6, Supporting Information).…”

“…The selected area electron diffraction (SAED) patterns could be indexed into the diffraction spots of the [001] zone, indicating the single crystal phase of TiO 2 judged by the diffraction spots of tetragonal (002) and (020) facets (Figure 2c). [ 32,33,40,41 ] The diffraction pattern at the edge of FTO/TiO 2 /Cu x O/CeO 2 presented some diffraction ring patterns based on the single crystal pattern, as shown in Figure 2d. Combining the measured spacing with the XRD crystal plane data, the diffraction rings were attributed to CeO 2 (111), CeO 2 (200), and Cu 2 O (200) crystal planes.…”

“…SEM images disclose that the morphology evolution of FTO/TiO 2 /Cu 2 O was quite different by varying the amount of NH 3 • H 2 O and Ce 3+ as seen in Figure 1c,d 002) and (020) facets (Figure 2c). [32,33,40,41] The diffraction pattern at the edge of FTO/TiO 2 /Cu x O/CeO 2 presented some diffraction ring patterns based on the single crystal pattern, as shown in Figure 2d. Combining the measured spacing with the XRD crystal plane data, the diffraction rings were attributed to CeO 2 (111), CeO 2 (200), and Cu 2 O (200) crystal planes.…”

Ultrathin Diamond Nanofilms—Development, Challenges, and Applications

“…OTEs arise as a technological component for a variety of applications ranging from touch displays and panels via photo‐electrochemistry [ 230 ] to optoelectronic devices (i.e., related to spectroelectrochemistry). [ 231 ] Traditionally, OTEs are based on the deposition of a thin conductive material, that is, a conductive metal, on a transparent substrate, that is, quartz, glass or plastic.…”

Enhanced Visible-Light-Driven Photoelectrochemical Activity in Nitrogen-Doped TiO2/Boron-Doped Diamond Heterojunction Electrodes

“…To suppress the recombination and promote the separation of photogenerated carriers, heterojunctions have been fabricated by combining TiO 2 and different materials (such as BDD, NiTiO 3 , g-C 3 N 4 , CdS, etc.) to achieve better catalytic performance. − Boron-doped diamond (BDD), the p-type semiconductor, is one of the attractive candidates due to its wide potential window, which can supply a sufficient bias voltage to enhance the PEC performance of TiO 2 . Moreover, BDD also shows unique properties including low background current, long-term robustness against mechanical damage, high corrosion resistance, and high thermal conductivity .…”