A Review on Halide Perovskite-Based Photocatalysts: Key Factors and Challenges

Abstract

A growing number of research articles have been published on the use of halide perovskite materials for photocatalytic reactions. These articles extend these materials' great success from solar cells to photocatalytic technologies such as hydrogen production, CO₂ reduction, dye degradation, and organic synthesis. In the present review article, we first describe the background theory of photocatalysis, followed by a description on the properties of halide perovskites and their development for photocatalysis. We highlight key intrinsic factors influencing their photocatalytic performance, such as stability, electronic band structure, and sorption properties. We also discuss and shed light on key considerations and challenges for their development in photocatalysis, such as those related to reaction conditions, reactor design, presence of degradable organic species, and characterization, especially for CO₂ photocatalytic reduction. This review on halide perovskite photocatalysts will provide a better understanding for their rational design and development and contribute to their scientific and technological adoption in the wide field of photocatalytic solar devices.

Figure 1

(a) Schematic showing how the absorption of a photon of energy hv leads to the separate charge carriers being used for photocatalytic reactions. (b) Schematic showing the thermodynamic (the straddling of the reaction potentials) and kinetic requirements (the overpotential needed as a driving force) for photocatalysis upon the absorption of a photon by a heterogeneous photocatalyst.

Figure 2

(a) Halide gradient was proposed to drive the charges to the surface, leading to high levels of H₂ production. Reproduced from ref (16). Copyright 2018 American Chemical Society. (b) Black phosphorene-MAPbI₃ catalyst shows high production over 100 h of illumination, with performance maintained after 1 month of storage. Reproduced with permission from ref (17). Copyright 2019, Elsevier.

Figure 3

(a) Production of H₂ (black) and O₂ (red), showing less than stoichiometric O₂ from H₂O splitting. The formation of peroxides was ruled out, so the authors could not explain the disparity. No products were observed in the absence of water. Reproduced with permission from ref (18). Under a CC license, 2020, MDPI. (b) Production of H₂ over four cycles for a lead halide perovskite, showing remarkable stability. Reproduced with permission from ref (19). Copyright 2021, Elsevier.

Figure 4

(a) Illustration of CsPbBr₃ QDs deposited on high surface area graphene oxide, with a diagram showing the energy step the electrons take as they migrate to GO. Reproduced from ref (24). Copyright 2017, American Chemical Society. (b) Photocatalytic production of CsPbBr₃ nanosheets, and production with the addition of transport layers and metal cocatalyst. The selectivity shifts from CO to CH₄. Reproduced from ref (21). Copyright 2020, American Chemical Society.

Figure 5

(a) Recyclability of CsSnBr₃ for the degradation of crystal violet. Reproduced with permission from ref (26). Copyright 2018, John Wiley and Sons. (b) Scheme showing the direct oxidation of MBT, which does not rely on standard water-derived radicals, as the reaction is conducted in hexane. Reproduced from ref (27). Copyright 2019, American Chemical Society.

Figure 6

Direct polymerization of 3,4-ethylenedioxythiophene through oxidation, leading to encapsulation of CsPbI₃ QDs with increased stability. Reproduced from ref (32). Copyright 2017, American Chemical Society.

Figure 7

(a) Crystalline structure of ABX3 halide perovskites. Reproduced with permission from ref (43). Copyright 2017, Springer Nature. (b) Schematic representation of the different dimensionalities of HPs, from 0D to 3D ones. Reproduced with permission from ref (44). Copyright 2020, John Wiley and Sons.

Figure 8

Schematic representation of (a) the hot-injection and (f) ligand-assisted reprecipitation (LARP) methods. Reproduced with permission from ref (54). Copyright 2021, John Wiley and Sons. Colloidal perovskite CsPbX₃ NCs (X = Cl, Br, I) show size- and composition-tunable bandgap energies in the entire visible spectral region with narrow and bright emission: (b) optical images of colloidal solutions in toluene under UV irradiation (λ = 365 nm); (c) PL spectra upon excitation of λ_exc = 400 or 350 nm for CsPbCl₃; (d) optical absorption and PL spectra; (e) time-resolved PL decays for all samples in (c) except CsPbCl₃. Reproduced fromref (39). Copyright 2015, American Chemical Society; (g) optical images of MAPbX₃ QDs under ambient light and UV lamp (λ = 365 nm); (h) PL emission spectra of MAPbX₃ QDs; (i) CIE color coordinates corresponding to the MAPbX₃ QDs (1–9, black circle), pc-WLED devices (blue lines), and NTSC standard (bright area); (j, k) schematic diagram and EL spectra of pc-WLED devices using green emissive MAPbBr₃ QDs and red emissive rare earth phosphor KSF. Reproduced from ref (38). Copyright 2015, American Chemical Society.

Figure 9

Schematic representation of a perovskite crystal (1–1–3) and its derivatives after replacing two divalent B-site cations with (2–1–6) a tetravalent cation, (3–2–9) a trivalent cation, and (2–1–1–6) a tri- and monovalent cation. The string of digits above the structures refers to the vacancy order of the ions, respectively. Reproduced from ref (78). Copyright 2015, American Chemical Society.

Figure 10

Proposed formation of CsPbBr₃@SiO₂ core–shell NPs, and XRD pattern highlighting stability of (a) CsPbBr₃ NCs and (b) CsPbBr₃@SiO₂ core–shell NPs. Reproduced from ref (84). Copyright 2018, American Chemical Society.

Figure 11

Specific gradient bandgap structure in FAPbX3. PL spectra under continuous illumination of materials with different thicknesses (a) 58 nm, (b) 239 nm, and (d) 1.3 μm (λ_exc = 405 nm). PL intensity of the two peaks of the medium thickness NP (c) as a function of the illumination time and (e) a schematic diagram of the gradient energy band structures. Reproduced with permission from ref (97). Copyright 2018, Wiley-VCH.

Figure 12

Sketch represents dependence between reaction time vs concentration of different morphological modifications and shape evolution of CsPbBr3 nanostructures during various reaction times (a, b) 10 min, (c) 30 min, (d) 40 min, (e) 90 min, and (f) 180 min. Scale bar is 100 nm. Reproduced from ref (48). Copyright 2015, American Chemical Society.

Figure 13

Normalized intensity photoconductance traces vs. time. Charge carrier dynamics obtained using various excitation intensities at (a) 165 K, (b) 240 K, and (c) 300 K, and (d) PL of MAPbI3 on Al2O3 vs temperature (circles) detected by integrating over the emission band on optical excitation at 514 nm. The dashed line represents an exponential fit to the data points yielding binding energy of 32 ± 5 meV. The solid line shows the yield of charges on assuming that thermal ionization is the only nonradiative decay channel. Reproduced from ref (113). Copyright 2014, American Chemical Society.

Figure 14

HPs model (a) H₂O–H₂CO₃ complex and (b) defect structure with embedded H₃O⁺ and HCO₃^–. The box represents the simulation cell which contains an H₂O–H₂CO₃ complex or H₃O⁺ – HCO₃^– ion pair. Due to the visualization, additional species can be observed. (c) Multimass thermal desorption spectroscopy of perovskite thin film and (d) after a 2L dose of CO₂ on a 2nd sample. Reproduced with permission from ref (127). Copyright 2018, The Royal Society of Chemistry.

Figure 15

Results of photocatalytic CO₂ reduction to CO (a) using CsPbBr₃/Cs₄PbBr₆, and CsPbBr₃ without and with CH₃OH, (b) using CsPbBr₃/Cs₄PbBr₆ and Co-doped CsPbBr₃/Cs₄PbBr₆ with CH₃OH (c) ¹³C NMR spectra for the liquid products ¹³CO₂ and CH₃OH and (b) CO₂ and ¹³CH₃OH as feedstocks and (e) schematic band structures diagram for CsPbBr₃/Cs₄PbBr₆ and Co-doped CsPbBr₃/Cs₄PbBr₆. Reproduced with permission from ref (130). Copyright 2020, The Royal Society of Chemistry.

Figure 16

(a) Variation in HCOOH (Δ) and CH₃OH (o) production with pressure for TiO₂ in suspension. Reproduced with permission from ref (134). Copyright 1996, Elsevier. (b) CH₃OH yield with pressure for Cu/TiO₂ in suspension. Reproduced with permission from ref (136). Copyright 2002, Elsevier.

Figure 17

(a) Evolution of CO and CH₄ from as-prepared and washed NCs. (b) Schematic representation of the possible photoreduction reactions on the surface of Cs₂AgBiBr₆ NCs. (c) Evolution of CO and CH₄ gases for as-prepared and washed Cs₂AgBiBr₆ NCs with respect to time. Reproduced with permission from ref (71). Copyright 2018, John Wiley and Sons.

Figure 18

(a) Simplified schematic of the setup with a stainless-steel photocatalytic reactor. Reproduced with permission from ref (173). Copyright 2021, Multidisciplinary Digital Publishing Institute. (b) Detailed layout of a typical continuous flow photocatalytic CO₂ reduction setup. Reproduced with permission from ref (160). Copyright 2017, Elsevier.

Figure 19

(a) Photoreactor setup for CO₂ reduction and hydrogenation reactions from the Eslava group at Imperial College London. (b) Close-up of mass flow controller configuration before the reactor and (c) the photoreactor.

Figure 20

Different commercial photoreactors. (a) Photoreactor m2 (Penn Photon Devices, LLC), (b) EvoluChem PhotoRedOx Box (HepatoChem), (c) air-cooled TAK120 system (HK Testsysteme GmbH), and (d) liquid-cooled TAK120-LC system (HK Testsysteme GmbH).

Figure 21

Rate of production of Pt-TiO₂@g-C₃N₄ composites in different solvents under (a) UV–visible and (b) visible light. No catalyst control experiments performed under (c) UV–visible and (d) visible light. Reproduced from ref (164). Copyright 2021, American Chemical Society.

Figure 22

(a) SEM images of MAPbI₃ with the atomic ratio for I/Pb from EDX mappings and (b) STEM image and EDX mappings of the sample for quantitative analysis. Reproduced with permission from ref (183). Copyright 2018, Springer Nature. (c, d) SAED patterns (A–D) of a single nanosheet at −120 °C and their azimuthal integration compared with the reference cards for the orthorhombic CsPbBr₃ phase (ICSD: 97851), CsBr (ICSD: 236387), CsPb (ICSD: 627071), and PbBr₂ (ICSD: 202134). (e) Zoomed-in view of the white-boxed regions in high-resolution TEM (HRTEM) images. Reproduced from ref (184). Copyright 2017, American Chemical Society.

Figure 23

Variation of the elemental ratios on the surface of MAPI crystals under (a) dark and (b) light conditions with time. Reproduced with permission from ref (191). Copyright 2018, Royal Society of Chemistry Maps of I/Pb ratio of the perovskite films after storage (c) in N₂ atmosphere and (d) under vacuum for 50 h. Reproduced from ref (192). Copyright 2018, American Chemical Society.