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When the size of metallic nanocatalysts is reduced to clusters or even single atoms, they can exhibit unique catalytic activity. Understanding the local atomic structure of these highly dispersed metal species is crucial for comprehending changes in catalytic behavior. In recent years, researchers have developed the electron pair distribution function (ePDF) method, which has been utilized to study the atomic short-order arrangement of various materials. However, this technique has not yet been applied to the local structure study of supported metallic nanocatalysts to complement other characterization results. In this study, we introduced the ePDF method to investigate nanocarbon-supported Pt materials, which have potential applications as an oxygen reduction reaction catalyst. We demonstrate that with differential pair distribution function and independent component analysis, ePDF can probe the local structure of supported metal species, even the single atoms, in microregions. This technique was further extended to in situ experiments, indicating its semiquantitative capacity of studying structural evolution. The ePDF method is expected to complement electron microscopy and extended X-ray absorption fine structure, providing deeper insights into the structure–performance relationship of catalysts. [ABSTRACT FROM AUTHOR]

Perovskite ferroelectrics with prominent nonlinear optical absorption have attracted great attention in the field of photonics. However, they are traditionally dominated by inorganic oxides and exhibit relatively small nonlinear optical absorption coefficients, which hinder their further applications. Herein, we report a new organic--inorganic hybrid bilayered perovskite ferroelectric, (C4H9NH3)2(NH2CHNH2)Pb2Br7 (1), showing an above-room-temperature Curie temperature (~322 K) and notable spontaneous polarization (~3.8 μC cm--2). Significantly, the unique quantum-well structure of 1 results in intriguing two-photon absorption properties with a giant nonlinear optical absorption coefficient as high as 5.76 X 103 cm GW--1, which is almost two-orders of magnitude larger than those of mostly traditional all-inorganic perovskite ferroelectrics. To our best knowledge, 1 is the first example of hybrid ferroelectrics with giant two-photon absorption coefficient. The mechanisms for ferroelectric and two-photon absorption are revealed. This work will shed light on the design of new ferroelectrics with two-photon absorption and promote their potentials in the photonic application. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) is an attractive electrochromic and storage material due to its reversible and sustainable electrochemical redox processes. However, the insufficient surface area and excessive charge intercalation after long-term cycling results in limited charge capacitance and unsatisfactory cycling stability. In this work, we demonstrate an innovative method to increase PANI's electrochromic and energy storage performance by incorporating MXene, to enhance electrochemical activity and reveal more active areas of ion/electron intercalation/deintercalation and charge transfer. The hydrogen bonds formed between N-H, C-H, and C-N of PANI and -OH and -O surface functional terminations of MXene further enhance the interface interaction. With substantial optical transmittance modulation and charge capacitance, excellent coloration efficiency, and outstanding durability, the PANI/MXene thin film demonstrates exceptional color-switching and energy storage characteristics. Furthermore, the sandwich device with a PANI/MXene thin film as the positive electrode and zinc foil as the negative electrode demonstrates exceptional electrochromic and Zn 2+ storage capability. This work raises possibilities for next-generation intelligent energy conversion and storage technologies and offers fresh perspectives on the design of ionic devices., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The precise control of pore structures in porous organic polymer (POP) materials is of paramount importance in addressing a wide range of challenges associated with gas separation processes. In this study, we present a novel approach to optimize the gas separation performance of POPs through the introduction of fluorine groups and figure out an important factor of reaction decision that whether the AlCl 3 -catalyzed polymerization is Scholl reaction or Friedel-Crafts alkylation. In the chloroform system, the steric hindrance of function groups could make direct coupling between the benzene rings difficult, which would lead to part solvent knitting (Friedel-Crafts alkylation) instead. The fluorinated polymers show enhanced surface area and pore size characteristics. Notably, the fluorinated polymers exhibited significantly improved adsorption and separation performance for SF 6 , as evidenced by an ideal adsorbed solution theory selectivity (SF 6 /N 2 , v: v = 50:50, 273 K) increase of 75.0, 668.8, and 502.8% compared to the nonfluorinated POPs. These findings highlight the potential of fluorination as a strategy for tailoring the properties of POP materials for advanced gas separation applications.

Global warming and heavy metal pollution pose tremendous challenges to human development, and photocatalysis is considered to be an effective strategy to solve these problems. Herein, copper(II) tetra (4-carboxyphenyl) porphyrin (CuTCPP) molecules were successfully in situ loaded onto Bi 4 O 5 Br 2 by a hydrothermal approach. A series of experimental results show that the light absorption capacity and photogenerated carrier separation efficiency were synchronously enhanced after the construction of CuTCPP/Bi 4 O 5 Br 2 composites. Hence, the as-prepared composites possess significantly improved photocatalytic ability for both CO 2 and Cr(VI) reduction. Specifically, CuTCPP/Bi 4 O 5 Br 2 -2 achieves a CO generation rate of 17.14 μmol g -1 under 5 h irradiation, which is twice as high as that of Bi 4 O 5 Br 2 (8.57 μmol g -1 ). Besides, the optimized CuTCPP/Bi 4 O 5 Br 2 -2 also exhibits a removal rate of 61.87% for Cr(VI) within 100 min under irradiation. Furthermore, the mechanism of CO 2 and Cr(VI) photoreduction was explored by in situ Fourier transform infrared spectroscopy and capture experiments, respectively. This work can be a reference toward the construction of photocatalysts with high activity for solar energy conversion.

Dry reforming of methane (DRM) has been investigated for more than a century; the paramount stumbling block in its industrial application is the inevitable sintering of catalysts and excessive carbon emissions at high temperatures. However, the low-temperature DRM process still suffered from poor reactivity and severe catalyst deactivation from coking. Herein, we proposed a concept that highly durable DRM could be achieved at low temperatures via fabricating the active site integration with light irradiation. The active sites with Ni-O coordination (Ni SA /CeO 2 ) and Ni-Ni coordination (Ni NP /CeO 2 ) on CeO 2 , respectively, were successfully constructed to obtain two targeted reaction paths that produced the key intermediate (CH 3 O*) for anticoking during DRM. In particular, the operando diffuse reflectance infrared Fourier transform spectroscopy coupling with steady-state isotopic transient kinetic analysis ( operando DRIFTS-SSITKA) was utilized and successfully tracked the anticoking paths during the DRM process. It was found that the path from CH 3 * to CH 3 O* over Ni SA /CeO 2 was the key path for anticoking. Furthermore, the targeted reaction path from CH 3 * to CH 3 O* was reinforced by light irradiation during the DRM process. Hence, the Ni SA /CeO 2 catalyst exhibits excellent stability with negligible carbon deposition for 230 h under thermo-photo catalytic DRM at a low temperature of 472 °C, while Ni NP /CeO 2 shows apparent coke deposition behavior after 0.5 h in solely thermal-driven DRM. The findings are vital as they provide critical insights into the simultaneous achievement of low-temperature and anticoking DRM process through distinguishing and directionally regulating the key intermediate species.

Chemiresistive sensing has been regarded as the key monitoring technique, while classic oxide gas detection devices always need an external power supply. In contrast, the bulk photovoltage of photoferroelectric materials could provide a controllable power source, holding a bright future in self-powered gas sensing. Herein, we present a new photoferroelectric ([ n -pentylaminium] 2 [ethylammonium] 2 Pb 3 I 10 , 1 ), which possesses large spontaneous polarization (∼4.8 μC/cm 2 ) and prominent visible-photoactive behaviors. Emphatically, driven by the bulk photovoltaic effect, 1 enables excellent self-powered sensing responses for NO 2 at room temperature, including extremely fast response/recovery speeds (0.15/0.16 min) and high sensitivity (0.03 ppm -1 ). Such figures of merit are superior to those of typical inorganic systems (e.g., ZnO) using an external power supply. Theoretical calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy measurements confirm the great selectivity of 1 for NO 2 . As far as we know, this is the first realization of ferroelectricity-driven self-powered gas detection. Our work sheds light on the self-powered sensing systems and provides a promising way to broaden the functionalities of photoferroelectrics.

A lamellar carbon nitride (CN) framework is one of the most promising materials for solar-driven hydrogen peroxide production. The low dielectric constant of the organic CN framework leads to severe recombination of the excitons, and the photon-to-chemical conversion efficiency is thus unsatisfactory. In this work, by polycondensation of the small molecules on the KCl crystal surface, K + -incorporated crystalline CN (CNK) frameworks show significantly extended periodicity of the stacking layers and in-plane orderly organized heptazine/triazine units. The crystalline CNK frameworks exhibit a series of favorable photophysical properties, such as enhanced photon absorption, negatively shifted LUMO potentials, and attenuated emissive decay of the excitons. The CNK frameworks thus present remarkable performance in the photocatalytic selective oxygen reduction reaction for hydrogen peroxide production, e.g., CNK framework from the polycondensation of NH 4 SCN on the KCl surface could produce hydrogen peroxide at a remarkable reaction rate of 26.7 mmol h -1 g -1 with a high apparent quantum yield of 25.0%, which is 23.5 times that on its counterpart synthesized in the absence of KCl. This method is generally applicable to all of the precursors for CN synthesis.

Benefiting from superior semiconducting properties and the angle-dependence of the bulk photovoltaic effect (BPVE) on polarized light, the two-dimensional (2D) hybrid perovskite ferroelectrics are developed for sensitive self-powered polarized photodetection. Most of the currently reported ferroelectric-driven polarized photodetection is restricted to the shortwave optical response, and expanding the response range is urgently needed. Here we report the first instance of a FAPbI 3 -derived (2D) perovskite ferroelectric, (BA) 2 (FA)Pb 2 I 7 ( 1 , BA is n -butylammonium, FA is formamidinium). It exhibited a notably high thermostability and broad-spectrum adsorption extending to around 650 nm. Significantly, 1 demonstrated ferroelectricity-driven self-powered polarized photodetection under 637 nm with an anisotropic photocurrent ratio of ∼1.96, ultrahigh detectivity of 3.34 × 10 12 Jones, and long-term repetition. This research will shed light on the development of new ferroelectrics for potential application in broad-spectrum polarization-based optoelectronics.

It remains a challenge to develop UV nonlinear optical (NLO) crystals that can achieve a desirable trade-off on UV absorption edge, second harmonic generation (SHG), and birefringence. Here we report a thiosulfate UV NLO crystal of a 2D van der Waals layered structure, [C(NH 2 ) 3 ] 2 SO 3 S. Remarkably, this thiosulfate realizes the desired trade-off, with a short absorption edge of 254 nm, a strong SHG response of approximately 2.8 times that of the benchmark KH 2 PO 4 , and a sufficient birefringence of 0.073 at the wavelength of 546 nm. In addition, it exhibits strong in-plane anisotropy of the SHG intensity. According to the first-principles calculations, the non- π -conjugated [SO 3 S] 2- anion is the dominant SHG functional gene, while the π -conjugated [C(NH 2 ) 3 ] + cation serves as the functional gene of birefringence. This is different from common UV NLO materials whose functionals of SHG and birefringence are the same. These findings indicate that combining different function genes may be an effective strategy to develop outstanding NLO materials with the desirable property trade-off.

Trace 17β-estradiol (E2) is persistent against advanced treatment when blended with higher concentrations of low-toxicity organics, thus wasting energy. A circulating-flow selective photoelectrocatalysis (CF-SPEC) system is established with a selective E2-TiO 2 -NR photoanode, accurately reducing 1 μg L -1 E2 to less than 0.1 ng L -1 along with eliminating estrogenic activity even when blended with natural organic matter (NOM) at a thousand times higher concentration. Such high efficiency is derived from the augmented selectivity and activity of E2-TiO 2 -NRs toward E2 during CF-SPEC. Under a flow, the difference in adsorption capacity between NOM and E2 is further amplified 5.6-fold. Furthermore, the higher initial • OH concentration and faster mass transfer jointly endow CF-SPEC with a stronger oxidation capacity. As a result, the removal of E2 increases by 58.7%, and the elimination of estrogenic activity increases 5.8-fold. In addition, deeper mineralization and less homo- and heterocoupling under CF-SPEC are observed, leading to more thorough estrogenic activity removal. Although additional energy is needed to maintain the flow, there is a 55% decrease in energy consumption due to the accurate removal capacity. This work suggests a combination of flow degradation and surface engineering that can be expanded for the selective removal of toxic trace pollutants in blended systems.

Circularly polarized light (CPL)-sensitive direct detection is attracting increasing attention owing to its various optical technology applications and ultracompact device structures. However, current CPL-sensitive direct detection mainly focuses on a single mode, whereas the visible-near-infrared (vis-NIR) dual-modal detection, which is important for improving device sensitivity and night-vision performance, still remains to be explored. Here, for the first time, the vis-NIR dual-modal CPL-sensitive direct detection is presented in bulk single crystals of two-dimensional chiral perovskite ( R -BPEA) 2 PbI 4 ( R -BPEA = ( R )-1-(4-bromophenyl)ethylammonium). Benefiting from the strong light-matter interaction of the layered structure, ( R -BPEA) 2 PbI 4 shows a two-photon absorption (TPA) coefficient of up to 55 cm/MW, which almost falls around the highest value of 2D hybrid perovskites. Notably, ( R -BPEA) 2 PbI 4 exhibits a high vis-NIR dual-modal CPL-sensitive direct detecting performance under both visible light (520 nm) and NIR light (800 nm), with the on/off ratios of current higher than 10 3 , and the anisotropy factors for photocurrent higher than 0.1. This work will shed light on the design of new chiral semiconductors with a large TPA coefficient and promote their applications in vis-NIR dual-modal CPL-sensitive direct detection.

High-Curie-temperature ( T c ) ferroelectrics have exhibited broad applications in optoelectronic devices. Recently, two-dimensional multilayered perovskite ferroelectrics with excellent photoelectric attributes are attracting increasing interest as new systems of photoferroelectrics. However, the effective tuning of the T c value of a multilayered perovskite photoferroelectric system still remains a huge challenge. Here, by a halogen substitution strategy to introduce bromine atoms on n -propylamine cations, the hybrid perovskite photoferroelectric (3-bromopropylaminium) 2 (formamidinium)Pb 2 Br 7 ( BFPB ) with a high T c value (348.5 K) was obtained. It is notable that BFPB adopts a two-dimensional bilayered inorganic framework, with tight linking to the organic cation by C-Br···Br-Pb halogen···halogen interactions and N-H···Br hydrogen bonds. Intriguingly, in comparison with the prototypical compound ( n -propylaminium) 2 (formamidinium)Pb 2 Br 7 , a remarkable augmentation of 85.2 K in the resulting T c value of BFPB is clearly observed, which further broadens the temperature range of its application. In combination with the remarkable ferroelectric and semiconducting attributes, the reversible bulk photovoltaic effect was realized in single crystals of BFPB . This finding can not only enhance the hybrid perovskite ferroelectric family but also further promote the photoelectric application of ferroelectrics.