Direct Z-Scheme Heterojunction of Semicoherent FAPbBr₃/Bi₂WO₆ Interface for Photoredox Reaction with Large Driving Force

Abstract

Metal halide perovskites with direct band gap and strong light absorption are promising materials for harvesting solar energy; however, their relatively narrow band gap limits their redox ability when used as a photocatalyst. Adding a second semiconductor component with the appropriate band structure offsets can generate a Z-scheme photocatalytic system, taking full advantage of the perovskite’s intrinsic properties. In this work, we develop a direct Z-scheme photocatalyst based on formamidinium lead bromide and bismuth tungstate (FAPbBr3/Bi2WO6) with strong redox ability for artificial solar-to-chemical energy conversion. With desirable band offsets and strong joint redox potential, the dual photocatalyst is shown to form a semicoherent heterointerface. Ultrafast transient infrared absorption studies employing selective excitation reveal synergetic photocarrier dynamics and demonstrate Z-scheme charge transfer mechanisms. Under simulated solar irradiation, a large driving force photoredox reaction (∼2.57 eV) of CO2 reduction coupled with benzyl alcohol oxidation to benzaldehyde is achieved on the Z-scheme FAPbBr3/Bi2WO6 photocatalyst, harnessing the full synergetic potential of the combined system.

Photocorrosion at Irradiated Perovskite/Electrolyte Interfaces

“…The product evolution rates did not match the expected 1:1 stoichiometry, and superoxide formation from O 2 was also shown. 87 Furthermore, the pristine FAPbBr 3 showed signs of degradation, yielding CO, which calls for further studies. Perovskite PCs with varying amount of iodide vacancies were also evaluated in the PC degradation of organic compounds, and the beneficial role of iodide vacancies via the increased production of radical O 2 •– species was claimed.…”

“…Various perovskite-based heterojunctions (both type II and Z-scheme) were employed for the photooxidation of benzyl alcohol to benzaldehyde. 83 , 86 , 87 In the type II case, the perovskite acts as a sensitizer that injects photoexcited electrons to the CB of TiO 2 ( Figure 3 A). 83 , 86 These electrons react with molecular oxygen and form reactive superoxide radicals.…”

Glycine‐Functionalized CsPbBr3 Nanocrystals for Efficient Visible‐Light Photocatalysis of CO2 Reduction

“…In the field of the photocatalysis of CO 2 conversion with MHP NCs‐based photocatalysts, continuous efforts have focused on surface/interface modification [16, 18–24] and heterojunction engineering [25–32] to increase the active sites and improve the separation efficiency of photogenerated carriers, achieving a great improvement in photocatalytic performance over the past few years. However, the long alkyl‐chain capping ligands in conventional MHP NCs will be unfavorable for the CO 2 adsorption and hinder the efficient carrier transport in MHP NCs‐based heterojunctions, [26, 27] which has not yet been recognized extensively.…”

“…[9] TheseM HP NCs have attracted ever-increasing attention recently in the photocatalytic field, [10][11][12][13] for applications such as photocatalysis of H 2 evolution, [14] photodegradation of organic pollutants, [15] photocatalysis of CO 2 reduction, [16] and photocatalytic organic synthesis. [17] In the field of the photocatalysiso fC O 2 conversion with MHP NCs-based photocatalysts, continuouse ffortsh ave focused on surface/interface modification [16,[18][19][20][21][22][23][24] and heterojunction engineering [25][26][27][28][29][30][31][32] to increase the active sites and improve the separatione fficiencyo fp hotogenerated carriers,a chieving ag reat improvementi np hotocatalytic performanceo ver the past few years. However,t he long alkyl-chain capping ligands in conventional MHP NCs will be unfavorable for the CO 2 adsorptiona nd hinder the efficient carriert ransport in MHP NCsbasedh eterojunctions, [26,27] which has not yet been recognized extensively.C onsidering that capping ligandsa re indispensable for the preparation of MHP NCs with good stabilitya nd low surface defect density, the employment of small functional organic molecules as capping ligandsc ould be an ideal solution to maintain colloidals tability andi mprove the photocatalytic CO 2 activity of MHP NCs-based photocatalysts.…”

Solar-Driven Hydrogen Generation by Metal Halide Perovskites: Materials, Approaches, and Mechanistic View

“…In this respect, it is worth mentioning here a very recent report of the development of a direct Z-scheme photocatalyst based on FAPbBr 3 /Bi 2 WO 6 with strong redox ability for solar-to-chemical energy conversion. 23 Such an approach must be further exploited for overall water splitting by MHPs-based systems.…”