Selenol-containing two-dimensional perovskite promotes visible-light-driven selective reduction of unsaturated ketones

Abstract

Semiconductors have shown growing promise for photocatalytic reactions due to their tunable band structures and efficient charge separation capabilities. Among them, metal halide perovskites (MHPs) have emerged as particularly attractive candidates owing to their intense light absorption and favorable charge transport properties; yet inefficient charge utilization often occurs in MHP-based photocatalysis due to undesired interfacial charge losses and lattice mismatches within the heterostructures. Herein, we report a two-dimensional perovskite (TMHP) photocatalyst, where selenol-functionalized organic cations are integrated into the lattice as both structural components and catalytic sites. This design enables efficient photoinduced charge separation and transfer from the [PbI₄]²⁻ layers to the selenol groups, achieving visible-light-driven reduction of α,β-unsaturated ketones with up to 87% yield across diverse substrates. Mechanistic studies reveal a radical-mediated pathway facilitated by the polarized lattice environment. This work demonstrates a new strategy for engineering molecular functionality into semiconductor lattices and creating integrated, efficient photocatalytic systems.

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Introduction

Metal halide perovskites (MHPs) have emerged as a rapidly developing family of semiconductor materials due to their exceptional absorption coefficients, tunable band structures, and superior charge transport properties.^1–3 These features mostly originate from the unique characteristic band edge constructed by the hybridization between s-orbitals of the metal cations (e.g., Pb²⁺ and Sn²⁺) and p-orbitals of halide anions (e.g., I⁻, Br⁻, and Cl⁻), which gives rise to direct bandgaps and favorable carrier dynamics.^4–6 Remarkably, MHPs have attracted considerable attention across diverse photocatalytic fields, including hydrogen production,^7–9 CO₂ reduction,^10–13 and organic synthesis such as C–H bond activation, C–X bond coupling (X = C, O, N, etc.),^14–16 and selective oxidation.¹⁷ These examples demonstrate MHPs as multifunctional photocatalytic platforms where tailored electronic structures and dynamic interfaces enable efficient solar energy conversion beyond conventional semiconductors.^18–20

The combination of MHPs with other materials through band alignment engineering has been widely explored to improve charge carrier separation. Existing strategies primarily involve solid–liquid interfacial transfer^7,14,21 or semiconductor heterostructures^{12,17,22–24} (Fig. 1a). However, the multiphase approach often suffers from charge recombination and sluggish surface redox kinetics,^16,25–27 while heterostructures face challenges such as energy-level misalignment, interfacial degradation,^28–31 and the need for complex multi-step synthesis to achieve lattice matching.^32–38 A photocatalyst that intrinsically integrates light absorption, charge generation, and catalytic transformation within a single crystalline phase would be highly desirable to overcome these limitations.

Fig. 1 Rational design of the MHP-based photocatalyst. (a) Schematic diagram of charge transfer models in metal halide perovskites as photocatalysts: solid–liquid interfacial transfer, heterojunction, and the proposed TMHP system in this study. The TMHP system features a single-phase crystalline architecture in which light-absorbing inorganic layers are integrated with catalytically active organic cations. (b) General crystal structures of three types of TMHPs: (HEA)₂PbI₄, (MEA)₂PbI₄, and (SEA)₂PbI₄ (HEA = NH₃⁺CH₂CH₂OH; MEA = NH₃⁺CH₂CH₂SH; SEA = NH₃⁺CH₂CH₂SeH), and (c) the corresponding DOS and pDOS patterns. All DOS/pDOS plots have been shifted so that the Fermi energy is at 0 eV for clear comparison of the near band edge states and band gap values. The valence band (VB) section sandwiched by blue and green lines represents the VB region where electrons can be excited by blue (450 nm) and green light (525 nm), respectively, to reach the conduction band minimum (shown with grey lines). (d) The contribution of pDOS in the valence band edges of the three types of TMHPs, in which electrons can be excited to the conduction band minimum under blue and green light irradiation, as defined in (c). The corresponding elemental proportion analyses are shown in Table S1. (HEA)₂PbI₄ cannot be effectively excited by green light due to its relatively large bandgap (2.69 eV).

Derived from conventional three-dimensional (3D) MHP structures by inserting bulky organic cations, two-dimensional MHPs (TMHPs) have shown unique features arising from the dimensionality reduction and structural modification induced by the spacers. The incorporation of organic cations with functional end groups leads to unrivalled tunability in the 2D lattice structures with programmable photophysical and chemical properties, which allows post-synthetic chemical reactions on TMHP scaffolds.^1,5,39,40 In addition, the atomically flat interface and sub-nanometer interlayer distance enable efficient energy and charge transfer between the inorganic layers and the organic cations, which is crucial for promoting the efficiency of TMHP-based energy conversion devices.^41–43 Earlier work employing TMHPs for catalytic reactions has shown strong potential in photocatalytic applications. However, most of the TMHPs are only utilized as the light absorber, in which the photocatalytic efficiency still significantly relies on the efficient charge transfer to the external active sites.^44–48

In this study, we sought to develop a new photocatalyst based on the rationally designed TMHP structures to integrate both the intense light-absorption and effective charge generation and transfer features of MHPs. The proposed TMHPs have suitable band gap (1.95–2.69 eV, Fig. 1c) to effectively convert visible light to charge carriers within the inorganic scaffolds,^39,49 which are effectively transferred to the functional end groups on the organic cations and directly used for the catalytic reactions (Fig. 1a). More importantly, the chalcogenol functional groups (–OH, –SH, and –SeH) have high chemical reactivity and have been widely used for organic reactions.^50–56 Therefore, we devised a TMHP structure containing a short organic chain with a unified formula of NH₃⁺-CH₂-CH₂-RH, where R=O, S, and Se (Fig. 1b). Density functional theory (DFT) calculations reveal that Se contributes 71% and 62% to the valence band edge within the excitation energy ranges of blue (450 nm) and green light (525 nm) irradiation, respectively, significantly exceeding the contributions of O and S atoms in analogues TMHP structures (Fig. 1c, d, S2 and Table S1). This dominance arises from several key factors: (i) diffuse 4p orbitals of the Se atom enhance delocalization and orbital hybridization; (ii) its lower electronegativity (2.55 for Se vs. 3.44 for O and 2.58 for S) promotes greater electron density near the valence band edge; and (iii) the longer Se–H bond length and higher covalency strengthen orbital overlap compared to the more localized O/S counterparts. Collectively, these properties enhance Se atom's role in light absorption and charge carrier generation under visible excitation. These results suggest that selenol-containing TMHPs facilitate efficient photo-induced charge separation with excited electrons and holes migrating to the inorganic layer and the selenol active sites, respectively, thereby promoting redox reactions.

Results and discussion

Preparation of selenol-containing TMHP

To experimentally verify the functions of selenols in the MHP system, we prepared the selenol-containing TMHP (SEA)₂PbI₄ (SEA = 2-hydroselenoethan-1-aminium (CCDC number: 2348172)) single crystals through a one-pot crystallization process (Fig. 2a). In an acidic aqueous solution, lead iodide (PbI₂) and 2,2′-diselanediylbis(ethan-1-aminium) (DSEA) cations were dissolved in hydrogen iodide (HI) solution (containing ≤1.5% of hypophosphorous acid (H₃PO₂)) to form the mother liquor. During this process, Se–Se bonds on DSEA cations are fully reduced by H₃PO₂ to form SEA cations.^56,57 This transformation occurs simultaneously with the crystallization of the TMHP structure, yielding distinctive orange plate-like crystal structures. Detailed crystallographic information and the structural refinement data are available in Table S2.

Fig. 2 Preparation and characterization of (SEA)₂PbI₄ crystals. (a) Schematic illustration of the preparation of (SEA)₂PbI₄. (b) Single-crystal structure of (SEA)₂PbI₄, where a and h refer to the penetration depth of the cations and the distance between two adjacent planes for the Pb centers in the [PbI₆]⁴⁻ octahedra, respectively. (c) Raman spectrum of the (SEA)₂PbI₄ crystals. An unknown impurity is denoted using an asterisk. Inset: stereo fluorescence microscope (SFM) image of a (SEA)₂PbI₄ crystal. (d) PXRD patterns of (SEA)₂PbI₄ crystals over time. (e) Absorption and PL spectra of (SEA)₂PbI₄.

Analysis of structural and optical properties

Similar to OH- and SH-containing TMHPs, (SEA)₂PbI₄ has a layered structure with a corner-sharing [PbI₆]⁴⁻ octahedral network. However, due to the significantly longer Se–H bond length (Se–H: 1.29 Å vs. S–H: 1.19 Å, O–H: 0.84 Å) the spatial configuration of the SEA ligand differs greatly from the ‘curled’ structure of the HEA and MEA ligands, instead adopting an extended conformation aligned with the growth direction of the layered structure (Fig. S1). This leads to a significantly expanded interlayer spacing of 12.10 Å in (SEA)₂PbI₄, which is 20% (2.05 Å) and 18% (1.81 Å) larger than those in (HEA)₂PbI₄ and (MEA)₂PbI₄, respectively (Fig. S3). The H⋯I distances (2.69 Å and 2.84 Å) between the H atoms on ammonium end groups and the adjacent I atoms (Fig. 2b) in (SEA)₂PbI₄ are notably shorter than the summation of van der Waals radii of H and I atoms (∼3.1 Å)⁵⁸ and those in (HEA)₂PbI₄ (2.75 Å) and (MEA)₂PbI₄ (2.86 to 2.92 Å), indicating strong hydrogen bonding interactions in (SEA)₂PbI₄ (Fig. S3). This interaction results in a positive penetration depth (a = 0.44 Å) of intercalating cations, defined as the distance between the primary NH₃⁺ group and the plane of terminal iodides, and also induces significant distortion of the inorganic framework, as evidenced by the small equatorial Pb–I–Pb angles of 147.6°, compared to those of (HEA)₂PbI₄ (159.8°), (MEA)₂PbI₄ (175.4°), and other reported TMHPs.^59–61

We next investigated the stability of the selenol-containing TMHP structure. Due to the relatively low bond dissociation energy of Se–H (305 kJ mol⁻¹) compared to S–H (344 kJ mol⁻¹) and O–H (428 kJ mol⁻¹), the selenol (Se–H) bond in freestanding molecules is much more prone to oxidation compared to thiols (S–H) and alcohols (O–H) and rapidly converts to diselenide (i.e., –Se–Se–) groups even under mild oxidative conditions.^56,62 Surprisingly, Se–H bonds in (SEA)₂PbI₄ are relatively stable even under the exposure to air with humidity up to 80%, as the notable Se–H stretching vibration signal at 2277 cm⁻¹ persists (Fig. 2c).^63,64 The TMHP structure even remains unchanged after the storage under ambient conditions (20 °C, 60–80% of humidity) for 28 days (Fig. 2d and S4). We ascribe the enhanced stability of the Se–H bonds to the formation of compact TMHP structures in which Se–H bonds are closely packed within the layered structure and protected by the inorganic components (Fig. 2b).

To gain insights into the intrinsic properties of these TMHPs, we turned our attention to optical absorption and photoluminescence (PL) spectroscopy. (SEA)₂PbI₄ exhibits an absorption edge at 548 nm (Fig. 2e), corresponding to a bandgap of 2.20 eV as derived from Tauc plot analysis (Fig. S5). This experimental value is consistent with the DFT-calculated bandgap of 2.30 eV (Fig. 1c), with the slight discrepancy (∼0.1 eV) attributable to DFT's typical underestimation of excitonic effects. The PL emission maximum at 608 nm (Stokes shift: ∼60 nm) further confirms a direct bandgap transition, consistent with the sharp absorption onset (Fig. 2e). Notably, the band gap of (SEA)₂PbI₄ is slightly larger than those of (HEA)₂PbI₄ (2.24 eV)^49,65 and (MEA)₂PbI₄ (2.09 eV),³⁹ reflecting the influence of the selenol group (–SeH) on electronic structure modulation (Fig. 1c). The small Stokes shift and strong absorption in the blue–green region (450–550 nm) suggest low exciton binding energy and efficient light-harvesting capabilities, positioning (SEA)₂PbI₄ as a promising candidate for visible-light photocatalysis.

Investigation on photocatalytic capability

Selenols are acidic and are readily deprotonated to form selenolate anions, which have been widely applied for nucleophilic addition/substitution.^56,66–69 However, because of Se–H bond's intrinsic instability against moisture and oxygen, most existing selenol-driven reactions heavily rely on the in situ formation of selenols (e.g., benzeneselenol,^57,70 H₂Se^71,72 or metallic hydrogen selenide⁷³), significantly limiting the applications of Se–H as a potential catalytically active site. Encouraged by the materials stability and the unique electronic structure, as well as the strong light absorption of (SEA)₂PbI₄, we sought to investigate its potential as a MHP-based photocatalyst. In this composite catalyst, the lead halide component can effectively absorb photon energy and generate sufficient free charge carriers, which are transferred to the selenol component to facilitate redox reactions.

To verify the effectiveness of (SEA)₂PbI₄ as a photocatalyst, we selected α,β-unsaturated carbonyl compounds as the substrates for demonstrating the capability of TMHPs for photoinduced selective redox reactions.^74,75 Specifically, chalcone was used as the model substrate due to its representative asymmetric enone model and well-defined redox behavior. The standard reaction was carried out under a nitrogen atmosphere and excited by visible-light irradiation with predesigned wavelengths, in which (SEA)₂PbI₄ and H₃PO₂ were used as the photocatalyst and stoichiometric reductant, respectively. Among the commonly used solvents in selenol reduction, we selected hexane as the standard solvent, as the reaction with it showed the best performance among all tested solvents. This is likely due to its non-polar nature, which better preserves the structural integrity of the perovskite catalyst, affording the reduced product 2a in a yield up to 81% (excitation wavelength λ_ex = 450 nm, Table 1, entries 1–5, measured by ¹H NMR using 1,3,5-trimethoxybenzene as the internal standard). Varying the catalyst loading between 0.1 and 0.2 equivalents showed negligible impact on the catalytic process (entries 5–8), with yields consistently over 80%. It is important to note that although DSEACl₂ and PbI₂ salts are capable of absorbing visible light in the blue light region (Fig. S6), the control reactions using these two light absorbers yield only 51% (DSEACl₂, entry 9) and < 5% of product (PbI₂, entry 10) under the same operating conditions, indicating the importance of the coexistence of selenol groups and lead halide units within a TMHP structure for boosting the photocatalytic efficiency.

Table 1 Optimization of reaction conditions for selective reduction of unsaturated ketones

Entry^a	λex (nm)	Catalyst (equiv.)	Solvent	Yield^b (%)
a Conditions: substrate 1a (0.1 mmol), H3PO2 (0.12 mmol, 50 wt%), (SEA)2PbI4, solvent (2.0 mL), N2, 60 °C, 16 h, under LED illumination.b Refers to ^1H NMR yield, which is calculated using 1,3,5-trimethoxybenzene as the internal standard.
1	450	(SEA)2PbI4 (0.20)	Isopropanol	56
2	450	(SEA)2PbI4 (0.20)	Toluene	46
3	450	(SEA)2PbI4 (0.20)	Chloroform	33
4	450	(SEA)2PbI4 (0.20)	Acetonitrile	29
5	450	(SEA)2PbI4 (0.20)	Hexanes	81
6	450	(SEA)2PbI4 (0.15)	Hexanes	82
7	450	(SEA)2PbI4 (0.10)	Hexanes	85
8	450	(SEA)2PbI4 (0.05)	Hexanes	34
9	450	DSEACl2 (0.10)	Hexanes	51
10	450	PbI2 (0.10)	Hexanes	Trace
11	—	(SEA)2PbI4 (0.10)	Hexanes	Trace
12	525	(SEA)2PbI4 (0.10)	Hexanes	87
13	525	DSEACl2 (0.10)	Hexanes	33
14	525	PbI2 (0.10)	Hexanes	Trace
15	450/525	—	Hexanes	Trace

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We next investigated the irradiation-dependent reactivity of the TMHP catalyst. Control experiments in the dark showed negligible chalcone conversion (entry 11), indicating the necessity of irradiation. Favored by the absorption spectrum of (SEA)₂PbI₄ in the broad regions shorter than 548 nm, the reaction can be driven by blue (λ_ex = 450 nm) and green (λ_ex = 525 nm) light with high product yield (85% and 87%, respectively, entries 7 and 12). In contrast, the control reactions using DSEACl₂ as the catalyst decreased from 51% under blue light to 33% (entry 13), suggesting more efficient charge separation and transfer in (SEA)₂PbI₄ under visible-light irradiation induced by the incorporation of lead halide layers.

Substrate scope for the reduction of α,β-unsaturated ketones

We further evaluated the substrate scope with the optimized reaction conditions (Fig. 3 and S7–S47). All chalcones, regardless of whether they contained electron-donating (2b–2e) or electron-withdrawing (2f–2j) substituents on the phenyl ring, were successfully reduced with isolated yields ranging from 37% to 81%. A clear electronic trend was observed: substrates bearing electron-donating groups afforded higher yields (e.g., 2b: 81%; 2c: 78%), while those with electron-withdrawing groups gave comparatively lower yields (2f–2j: 37–67%). This trend is consistent with the proposed radical-mediated mechanism, where electron-donating substituents stabilize the key radical-cation intermediate, thereby facilitating the reduction. Notably, for substrates containing multiple unsaturated bonds (e.g., with terminal allyl (1d) and propargyl (1e) groups on the aryl ring, or conjugated α,β,γ,δ-unsaturated structures (1k and 1l)), the reduction occurred selectively at the C=C bond in the α,β-unsaturated site with isolated yields from 36% to 69%, while other unsaturated bonds were preserved (Fig. 3). We ascribe the high chemoselectivity to the polarization effect arising from conjugation with the carbonyl group, which renders the β-carbon partially positively charged. The nucleophilic selenium atom on the surface of (SEA)₂PbI₄ therefore can attack the β-carbon via a 1,4-conjugate addition pathway, forming a β-seleno carbonyl intermediate that can subsequently undergo further reduction. Moreover, substrates with α,β-unsaturated C=C bonds on both sides of the central carbonyl (e.g., biphenylpentadienone (1m)) can be completely reduced to form fully saturated ketones with a considerably high yield of 54%, indicating the capability of multi-site activation with photoexcited (SEA)₂PbI₄. The selective reduction is found to be effective for extended types of substrates such as a naphthyl substituent (1n), heterocycles (1o and 1p), a sterically hindered α-substituted substrate (1q), an ester group (1r), a diketone (1s), and an aromatic alkynyl ketone (1aa), with isolated yields ranging from 30% to 73%.

Fig. 3 Substrate scope of photocatalytic reduction with various ketone structures. Reaction conditions: substrate 1 (0.1 mmol), H₃PO₂ (0.12 mmol, 50 wt%), (SEA)₂PbI₄ (0.01 mmol), hexane (2.0 mL), N₂, 60 °C, 16 h, under 525 nm LED illumination. Yields were isolated yields. ^aReaction time: 36 h. ^bH₃PO₂ (0.22 mmol). ^cAcetylene ketone 1aa can also be reduced to 2a under these conditions.

Mechanistic studies on the TMHP-driven photocatalytic reactions

To gain mechanistic insight into the selective reduction of unsaturated ketones better, related control experiments were conducted. First, excess equivalents of radical scavenger 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) were added to the catalytic system (Fig. 4a). We found that the formation of the product was inhibited significantly, regardless of whether (SEA)₂PbI₄ or DSEACl₂ was used as the catalyst, indicating that radical species might be involved in the catalytic reduction process.

Fig. 4 Mechanistic investigation of TMHP-promoted photocatalytic reduction. (a) Inhibition of the reaction by the application of TEMPO as a radical trap. (b) ¹H NMR spectra (400 MHz, DMSO-d₆) of the solid residues from reactions of chalcone 1a with stoichiometric amounts of DSEACl₂ (blue line) or (SEA)₂PbI₄ (orange line) under standard reaction conditions but in the dark. The residual solvent DMSO, the trace amount of water, and unknown impurities are denoted using a circle (●), a black diamond (◆), and an asterisk (*), respectively. (c) Proposed mechanism for (SEA)₂PbI₄-catalyzed selective reduction of α,β-unsaturated ketones using chalcone as the model substrate: under irradiation, (SEA)₂PbI₄ (I) generates photoinduced charge carriers, which undergo intramolecular transfer to form surface-bound selenium radicals (II) (step 1, detailed sub-steps are shown in the blue dashed box). Meanwhile, the chalcone (1a) undergoes 1,4-addition with the surface-bound selenol species (I), forming the β-seleno carbonyl intermediate (III) (step 2); the as-formed selenium radical (II) further promotes the cleavage of the Se–C bond on TMHP surfaces (III) to generate the radical cation intermediate (IV) and diselenide species (step 3); the intermediate (IV) is finally reduced by the photoexcited TMHPs to yield the saturated product (2a) (step 4), while the diselenide is recycled to selenium species by H₃PO₂/H₂O (step 5) to complete the catalytic cycle.

To investigate the role of irradiation in the catalytic process, we next conducted control experiments without irradiation and collected the solid and liquid to analyze the progress of the reaction. Only a negligible amount of product (yield below 2%) was detected from the solution after a 16-h reaction in the dark, while the β-seleno carbonyl intermediates were observed in solid-phase residues when either (SEA)₂PbI₄ or DSEACl₂ was used in stoichiometric amounts, as confirmed by NMR and mass spectrometry (MS) studies of the isolated solid residues (Fig. 4b and S48–S50). These results hint at the 1,4-addition on the α,β-unsaturated moiety between the selenol groups and the chalcone substrate even in the absence of light, consistent with the previous reports.^71,72,74 These results indicate that light is not required for the formation of the β-seleno carbonyl intermediate but rather functions as an excitation source absorbed by the TMHP to generate excitons that drive the subsequent reduction steps.

A standard hot filtration test was carried out to evaluate the heterogeneous nature of the TMHP catalysis. After removal of the solid catalyst at the reaction temperature, the filtrate was further irradiated under identical conditions. ¹H NMR analysis showed that the product yield remained virtually unchanged, increasing only from 20% to 21% (Fig. S51), demonstrating that no catalytically active species leach into solution and confirming the heterogeneous nature of the TMHP catalysis.

The material characterization and mechanistic studies lead us to a more detailed model of the TMHP-promoted photocatalytic process (Fig. 4c). Upon irradiation, the inorganic [PbI₄]²⁻ layer of (SEA)₂PbI₄ (I) absorbs photons, generating electron–hole pairs, with the electron and hole becoming localized on the Pb and I atoms of the inorganic framework, respectively. The hole residing on the I atom renders it electron-deficient. This electron-deficient I atom can abstract an electron from the nearby Se–H group via the hydrogen-bonding network, given that Se is the most electropositive site in the organic cation. This leads to the oxidation of selenol, yielding selenyl radical cations (II) as the intermediate species (step 1).

Meanwhile, the unsaturated ketone molecule (taking chalcone (1a) for example) undergoes nucleophilic 1,4-conjugate addition with the surface-bound selenol species (I), forming the intermediate (III), which is a spontaneous reaction (step 2, ΔG₁ = −11.3 kcal mol⁻¹, Scheme S1). Subsequently, III interacts with the surface selenyl radical cation (II, formed in situ from the visible light excitation process as shown in Fig. 4c) and triggers exothermic heterolytic Se–C cleavage (step 3, ΔG₂ = −16.0 kcal mol⁻¹), yielding radical-cation-containing intermediate IV, accompanied by the release of the diselenide structure (V). Subsequent electron transfer from the photoexcited inorganic layer reduces IV to the saturated product 2a, completing the selective reduction (step 4) with ΔG₃ = −13.6 kcal mol⁻¹. With the presence of H₂O and H₃PO₂, diselenide (V) is reduced to form selenol-containing I and completes the catalytic cycle (step 5).

It is important to note, however, that a primary limitation of this system is the participation of only surface-exposed selenol ligands in the catalytic cycle. The progressive loss of these SEA groups through repeated redox cycling results in gradual degradation of the TMHP catalyst (Fig. S52 and S53). This is consistent with the catalytic recycling experiments, which show a gradual decrease in product yield from 87% in the first cycle to 13% after four cycles (Fig. S54). Future improvements in reaction parameters, such as the rational design of new selenol-containing cations and optimization of the solvent environment, are expected to enhance the stability of TMHP-based materials and broaden their utility in heterogeneous catalytic reactions.

Conclusions

In this work, we have developed a new photocatalyst design by integrating selenol-containing organic cations into two-dimensional metal halide perovskites (TMHPs), creating a unified crystalline platform (SEA)₂PbI₄ that combines efficient light absorption, charge carrier generation and separation, and catalytic activation. The hybrid framework demonstrates notable stability for typically labile Se–H bonds and enables visible-light-driven selective reduction of α,β-unsaturated ketones with a broad substrate scope and high chemoselectivity. Mechanistic investigations reveal a radical-mediated pathway in which photoexcited charges from the inorganic layers activate selenol groups to promote selective reduction reactions on various types of unsaturated carbonyl compounds, highlighting the unique synergy between perovskite photophysics and incorporated molecular catalysis. This work advances the fundamental understanding of TMHP-based photocatalysis and provides a general design strategy for multifunctional perovskite materials. By overcoming traditional limitations of charge recombination and lattice mismatches, our approach opens new possibilities for applying perovskites in light-driven selective organic transformations and chemical synthesis.

Author contributions

W. L. and L. L contributed equally. W. L. and Z. Y. designed the study and wrote the paper. W. L. synthesized and characterized the TMHPs. W. L., L. L., J. L. (Jingpeng Li), W. Q., and X. Z. conducted the catalytic experiments. J. L. (Jialong Liu) prepared the carbonyl substrates. Y. Z., G. Y., and T. Z. performed the computational studies. All authors approved the final version of the manuscript.

Conflicts of interest

A provisional patent application CN119059949A was filed on December 3, 2024 by Sun Yat-sen University. The remaining authors declare no competing interests.

Data availability

CCDC 2348172 contains the supplementary crystallographic data for this paper.⁷⁶

The data supporting the findings of this study are available in the article and its supplementary information (SI) or from the corresponding authors upon reasonable request. Supplementary information: materials and methods, additional structural and optical characterization, substrate synthetic procedures, summary of NMR data, and supplementary mechanistic studies. See DOI: https://doi.org/10.1039/d5sc09706a.

Acknowledgements

All calculations were carried out using the Tianhe-2 (TH-2) super computer clusters (Guangzhou, Guangdong, China) and resources provided by Digital Research Alliance of Canada. Z. Y. would like to acknowledge financial support from the National Natural Science Foundation of China (no. 21905316, 22175201, and 22475239), the Department of Science and Technology of Guangdong Province (no. 2019QN01C108), and Sun Yat-sen University. T. Z. thanks the Natural Sciences and Engineering Research Council (NSERC) of Canada (no. RGPIN-2024-06286) for financial support. All single crystal X-ray diffraction tests were conducted by the Testing Center of Sun Yat-sen University. X. Z. would like to acknowledge financial support from the National Natural Science Foundation of China (no. 22171292 and 22371308). L. L. thanks the Guangzhou Science and Technology Plan, Basic and Applied Basic Research Special Topic, Young Doctoral “Sailing” Project (no. 2025A04J4290), and the Fundamental Research Funds for the Central Universities, Sun Yat-sen University (no. 24qnpy048) for financial support.

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Footnote

† These authors contributed equally to this work.

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