Diffusion‐Controlled Z‐Scheme‐Steered Charge Separation across PDI/BiOI Heterointerface for Ultraviolet, Visible, and Infrared Light‐Driven Photocatalysis

Abstract

Constructing heterojunctions is an efficient approach for enhancing charge separation to optimize photoreactivity. Although the aligned built‐in electric fields across the heterointerface are generally considered as the main driving force for charge separation, diffusion‐controlled charge separation also happens, which is poorly investigated in photocatalytic heterojunctions. Here, a perylene‐3,4,9,10‐tetracarboxylic diimide (PDI)–bismuth oxyiodide (BiOI) heterojunction is elaborately fabricated by in situ successive ion layer adsorption and reaction (SILAR) methods. Utilizing Kelvin probe force microscopy (KPFM), the local separation of photogenerated charge carriers across the heterointerface is directly mapped, which obeys a Z‐scheme mechanism. Experimental results and theoretical simulations reveal that the differences of electron densities between PDI and BiOI enable a diffusion‐controlled charge separation process, which overwhelm that of built‐in electric fields across heterointerfaces. Benefiting from the effective charge separation driven by a diffusion‐controlled driving force, this PDI/BiOI heterojunction exhibits superior photocatalytic activities even under infrared (IR)‐light irradiation. These findings highlight the importance of diffusion‐controlled charge separation, and also offer useful roadmaps for the design of high‐performance heterojunction photocatalysts for down‐to‐earth applications.

Heterostructured Perylene Diimide (PDI) Supramolecular Nanorods with SnO2 Quantum Dots for Enhanced Visible‐Light Photocatalytic Activity and Stability

“…Under visible light illumination, there were slight positive shifts in the binding energy of C 1s (by 0.11 eV) (Figure 6B) and N 1s (by 0.11 eV) (Figure 6C) spectra, demonstrating that the electron density of PDI supramolecular nanorods was decreased. Meanwhile, under light irradiation, the characteristic Sn 3d spectra of 4 %‐SnO 2 QDs/PDI showed a negative shift (by 0.17 eV) (Figure 6D), demonstrating an increase in the electron density on the SnO 2 QDs [26] . Hereby, migration of photogenerated electrons from PDI to SnO 2 QDs when exposed to visible light was confirmed, as revealed in Scheme 1.…”

“…Meanwhile, under light irradiation, the characteristic Sn 3d spectra of 4 %-SnO 2 QDs/PDI showed a negative shift (by 0.17 eV) (Figure 6D), demonstrating an increase in the electron density on the SnO 2 QDs. [26] Hereby, migration of photogenerated electrons from PDI to SnO 2 QDs when exposed to visible light was confirmed, as revealed in Scheme 1.…”

Manipulating Excitonic Effects in Layered Bismuth Oxyhalides for Photocatalysis

“…By constructing heterojunction, the band-edge charge density can be disordered, particularly around the interface, thereby promoting excitons dissociation and enhancing the charge-carrier-dominated photocatalytic reactions. ,− Zhou et al designed a binary hybrid single-unit-cell Bi 3 O 4 Br/AgI heterojunction via an in situ deposition-precipitation method . According to the high-resolution XPS spectra of the AgI/Bi 3 O 4 Br heterojunction, the slight shift of O 1s peaks to lower binding energy indicated the strong interfacial interaction between AgI and Bi 3 O 4 Br (Figure a).…”

Biosynthesized δ-Bi2O3 Nanoparticles from Crinum viviparum Flower Extract for Photocatalytic Dye Degradation and Molecular Docking

“…As per reports, several semiconductor-based materials have been applied as photocatalysts in diverse applications. − Among semiconducting materials, Bi 2 O 3 nanomaterials are gaining significant interest in the areas of fuel cells, ceramics, sensors, optoelectronics, energy storage, and photocatalysis as they have a large band gap, ionic conductivity, dielectric-permittivity, photoconductivity, morphology, and so forth. − Basically, Bi 2 O 3 occurs in six polymorphs with different band gaps: monoclinic α-Bi 2 O 3 (stable at 730 °C), face-centered cubic δ-Bi 2 O 3 (stable at 730–825 °C), tetragonal β-Bi 2 O 3 , BCC γ-Bi 2 O 3 , triclinic ε-Bi 2 O 3 , and orthorhombic ω-Bi 2 O 3 . The δ-Bi 2 O 3 has an FCC arrangement with fluorite structure, wherein 75% oxygen occupied in a tetrahedral manner.…”