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A smart covalent organic framework (Por-HQ-COF) possessing environment-initiated switchable photocatalytic reduction and oxidation and H2O2 production, is constructed by engineering at a molecular level and the local phenol-quinone structure of the skeletal building blocks. As a smart photocatalyst, Por-HQ-COF based on phenol-quinone transformation can convert into Por-BQ-COF intelligently with a trigger, and vice versa.

Abstract

Developing multifunctional photocatalysts with intelligent self-adjusting is of great significance in the photocatalytic process. Herein, a smart covalent organic framework (Por-HQ-COF) with a phenol-quinone conversion structure with pH changes is constructed for photooxidation, photoreduction, and H2O2 production. As a smart photocatalyst, Por-HQ-COF can convert into Por-BQ-COF intelligently with a trigger including solution pH, and vice versa. The reconstruction of phenol-quinone conversion not only significantly alters the morphologies and the specific surface areas of the COF, but also leads to an entirely change in the band energy and charge distribution to influence photoelectric properties. As a result, under acidic conditions, Por-BQ-COF converts into Por-HQ-COF automatically and can photoreduce high concentration Cr(VI) to Cr(III) efficiently. Under neutral conditions, the superoxide anions (·O2 −) initiate the Por-HQ-COF reconstruction into Por-BQ-COF to accelerate photooxidation to degrade high-concentration TC. Under alkaline conditions, Por-HQ-COF converts into Por-BQ-COF, can effectively photosynthesize H2O2 (1525 µmol h−1 g−1 at λ > 420 nm) in the absence of any sacrificial reagents, and reveal the strong alkalinity lower the energy barrier of hydrogen extraction from H2O and clarify active sites for H2O2 production. This work provides a new strategy for developing smart photocatalysts and fulfill the application across the full pH environment.

F-N-C catalysts with high density of accessible sites (D-Fe-N/C) is fabricated by a cascade capturing strategy. Systematic structural and electrochemical characterizations demonstrate that the high active site density and site utilization enable D-Fe-N/C showcases excellent ORR performance, which is further verified in laminated zinc-air batteries with remarkable durability and temperature-adaptive.

Abstract

Designing single-atom catalysts (SACs) with high density of accessible sites by improving metal loading and sites utilization is a promising strategy to boost the catalytic activity, but remains challenging. Herein, a high site density (SD) iron SAC (D-Fe-N/C) with 11.8 wt.% Fe-loading is reported. The in situ scanning electrochemical microscopy technique attests that the accessible active SD and site utilization of D-Fe-N/C reach as high as 1.01 × 1021 site g−1 and 79.8%, respectively. Therefore, D-Fe-N/C demonstrates superior oxygen reduction reaction (ORR) activity in terms of a half-wave potential of 0.918 V and turnover frequency of 0.41 e site−1 s−1. The excellent ORR property of D-Fe-N/C is also demonstrated in the liquid zinc-air batteries (ZABs), which exhibit a high peak power density of 306.1 mW cm−2 and an ultra-long cycling stability over 1200 h. Moreover, solid-state laminated ZABs prepared by presetting an air flow layer show a high specific capacity of 818.8 mA h g−1, an excellent cycling stability of 520 h, and a wide temperature-adaptive from −40 to 60 °C. This work not only offers possibilities by improving metal-loading and catalytic site utilization for exploring efficient SACs, but also provides strategies for device structure design toward advanced ZABs.

The electrocatalytic reduction of nitrate into value-added NH3 not only facilitates wastewater denitrification but also promotes nitrogen circulation. The hierarchical carbon-based metal-free electrocatalyst with multi-topological defect-induced active sites in graphene sheets/outside carbon layer and the pristine carbon nanotubes as the conductive core achieves high activity and durability for electrocatalytic reduction of nitrate in a wide pH range.

Abstract

The electrocatalytic reduction of nitrate (eNO3 −RR) to ammonia (NH3) across varying pH is of great significance for the treatment of practical wastewater containing nitrate. However, developing highly active and stable catalysts that function effectively in a wide pH range remains a formidable challenge. Herein, a hierarchical carbon-based metal-free electrocatalyst (C-MFEC) of winged carbon coaxial nanocables (W-CCNs, in situ generated graphene nanosheets and outside carbon layer with abundant topological defects from pristine carbon nanotubes, CNTs), is prepared through moderate oxidation of CNTs and the subsequent introduction of topological defects. The W-CCNs feature functional separation properties, with an inner core of pristine CNTs that facilitates efficient charge transfer, while the outer shell is composed of in situ generated graphene nanosheets and carbon layers enriched with topological defects characterized by distinct carbon atom configurations, which play a crucial role in promoting the adsorption of NO3 −, the dissociation of water, and the N─H bond formation. This innovative design enables the C-MFEC to exhibit outstanding performance for eNO3 −RR, operating efficiently with the NH3 yield rates of 49.5, 75.3, and 88.1 g h−1 gcat. −1 in acidic, neutral, and alkaline media, respectively. Such performance metrics not only outshine C-MFECs but also rival or surpass those of certain metal-based catalysts.

Narrowband response of organic semiconductors determines the band selectivity and anti-interference in the photodetection process. For constructing strong anti-interference photodetectors, a general strategy is developed to achieve narrowband ultraviolet-responsive organic semiconductors by tuning the absorption state and intermolecular potential of organic semiconductor.

Abstract

Narrowband response of organic semiconductors determines the band selectivity and anti-interference of the organic photodetectors, which are pursued for a long time but have not yet been resolved in the UV band. Herein, a feasible strategy is developed to realize narrowband UV response by tuning the absorption state and intermolecular potential of organic semiconductors. The as-designed non-Donor-Acceptor molecule, 2,5-diphenylthieno[3,2-b]thiophene (2,5-DPTT), exhibits narrowband absorption by fully suppressing the charge transfer state absorption. Simultaneously, the intermolecular potential is significantly enhanced (to ≈90 KJ mol−1) by modulating the molecular planarity. Consequently, the UV photodetector based on 2,5-DPTT achieves excellent narrowband response at 310 nm wavelength and a record-breaking photosensitivity (P = 1.21 × 106) in the deep UV range. In the demonstration application of flame alarm, the flame detector based on 2,5-DPTT single crystal exhibits excellent anti-interference capability. This work provides the inspiration for designing narrowband responsive organic semiconductors and building up multifunctional optoelectronic devices.

A reliable benchmark for qualitative and quantitative analysis of oxygen functional groups on carbon surface is established by in situ characterizations and theoretical calculations. And the dynamic evolution of carbon surface reveals the special flame-retardant effect and anchor metal ability of oxygen functionalities on carbon materials. These findings strengthen the understanding of carbon surface chemistry from an atomic perspective.

Abstract

The explicit roles of the hardly avoidable oxygen species on carbon materials in various fields remain contentious due to the limitations of characterization techniques, which lead to a lack of fundamental understanding of carbon surface chemistry. This study delves exhaustively into the comprehension of the features of different oxygen-modified carbons through the dynamic evolution of surficial oxygen functional groups. Significant differences of thermal stability and electronic properties among various oxygen species are elucidated via in situ characterizations and theoretical calculations, providing a reliable benchmark for identifying oxygen functional groups on carbon materials. The chemical properties of the carbon materials are simultaneously investigated to show the influence of the oxygen functional groups on carbon structures, redox stability, and scalable metal adsorption. These findings not only consider the common misconception that oxygen species produced under various conditions possess identical properties but also raise awareness of understanding carbon surface chemistry in the atomic level.

A novel organic electrochemical device achieving over 90% reversible THz modulation via a conducting polymer is developed. The device demonstrates stability under repeated and continuous voltage switching and can operate in either depletion or accumulation modes. This device introduces a new option for future THz wireless sensing and communications, and application scope for organic mixed ionic-electronic conductors.

Abstract

The sub-Terahertz and Terahertz bands play a critical role in next-generation wireless communication and sensing technologies, thanks to the large amount of available bandwidth in this spectral regime. While long-wavelength (microwave to mm-Wave) and short-wavelength (near-infrared to ultraviolet) devices are well-established and studied, the sub-THz to THz regime remains relatively underexplored and underutilized. Traditional approaches used in the aforementioned spectral regions are more difficult to replicate in the THz band, leading to the need for the development of novel devices and structures that can manipulate THz radiation effectively. Herein a novel organic, solid-state electrochemical device is presented, capable of achieving modulation depths of over 90% from ≈500 nm of a conducting polymer that switches conductivity over a large dynamic range upon application of an electronically controllable external bias. The stability of such devices under long-term, repeated voltage switching, as well as continuous biasing at a single voltage, is also explored. Switching stabilities and long-term bias stabilities are achieved over two days for both use cases. Additionally, both depletion mode (always “ON”) and accumulation mode (always “OFF”) operation are demonstrated. These results suggest applications of organic electrochemical THz modulators in large area and flexible implementations.

Nature Materials, Published online: 07 February 2025; doi:10.1038/s41563-024-02112-7

Sublattice amorphization is revealed as the deformation mechanism of Ag2Te1–xSx (0.3 ≤ x ≤ 0.6), based on which an iterative crystalline–amorphous transition strategy is proposed to enable these bulk inorganic semiconductors with metal-like processability.

Nature Materials, Published online: 07 February 2025; doi:10.1038/s41563-024-02109-2

Pentagonal PdSe2 induces anisotropic, gate-tunable spin–orbit coupling in graphene, enabling a tenfold modulation of in-plane spin lifetimes at room temperature and providing opportunities to control spin dynamics in van der Waals materials.

Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D4EE04063E, Review ArticleWenhao Xu, Libo Li, Yangmingyue Zhao, Suo Li, Hang Yang, Hao Tong, Zhixuan Wang
In the pursuit of sustainable energy, lithium-ion batteries (LIBs) have revolutionized storage solutions and advanced the development of electric vehicles. However, as LIBs near their energy density limits and face...
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