The low-cost room-temperature sodium-sulfur battery system is arousing extensive interest owing to its promise for large-scale applications. Although significant efforts have been made, resolving low ...sulfur reaction activity and severe polysulfide dissolution remains challenging. Here, a sulfur host comprised of atomic cobalt-decorated hollow carbon nanospheres is synthesized to enhance sulfur reactivity and to electrocatalytically reduce polysulfide into the final product, sodium sulfide. The constructed sulfur cathode delivers an initial reversible capacity of 1081 mA h g
with 64.7% sulfur utilization rate; significantly, the cell retained a high reversible capacity of 508 mA h g
at 100 mA g
after 600 cycles. An excellent rate capability is achieved with an average capacity of 220.3 mA h g
at the high current density of 5 A g
. Moreover, the electrocatalytic effects of atomic cobalt are clearly evidenced by operando Raman spectroscopy, synchrotron X-ray diffraction, and density functional theory.
Both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are crucial to water splitting, but require alternative active sites. Now, a general π‐electron‐assisted strategy to ...anchor single‐atom sites (M=Ir, Pt, Ru, Pd, Fe, Ni) on a heterogeneous support is reported. The M atoms can simultaneously anchor on two distinct domains of the hybrid support, four‐fold N/C atoms (M@NC), and centers of Co octahedra (M@Co), which are expected to serve as bifunctional electrocatalysts towards the HER and the OER. The Ir catalyst exhibits the best water‐splitting performance, showing a low applied potential of 1.603 V to achieve 10 mA cm−2 in 1.0 m KOH solution with cycling over 5 h. DFT calculations indicate that the Ir@Co (Ir) sites can accelerate the OER, while the Ir@NC3 sites are responsible for the enhanced HER, clarifying the unprecedented performance of this bifunctional catalyst towards full water splitting.
HER and OER! The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are crucial to water splitting, but require alternative active sites. Now, a general π‐electron‐assisted strategy to anchor single‐atom sites (M=Ir, Pt, Ru, Pd, Fe, Ni) on a heterogeneous support is reported. The M atoms can simultaneously anchor on two distinct domains of the hybrid support, four‐fold N/C atoms, and centers of Co octahedra.
Developing dopant‐free hole transporting materials (HTMs) is of vital importance for addressing the notorious stability issue of perovskite solar cells (PSCs). However, efficient dopant‐free HTMs are ...scarce. Herein, we improve the performance of dopant‐free HTMs featuring with a quinoxaline core via rational π‐extension. Upon incorporating rotatable or chemically fixed thienyl substitutes on the pyrazine ring, the resulting molecular HTMs TQ3 and TQ4 show completely different molecular arrangement as well as charge transporting capabilities. Comparing with TQ3, the coplanar π‐extended quinoxaline based TQ4 endows enriched intermolecular interactions and stronger π–π stacking, thus achieving a higher hole mobility of 2.08×10−4 cm2 V−1 s−1. It also shows matched energy levels and high thermal stability for application in PSCs. Planar n‐i‐p structured PSCs employing dopant‐free TQ4 as HTM exhibits power conversion efficiency (PCE) over 21 % with excellent long‐term stability.
Quinoxaline derivatives, featuring with rotatable and chemically fixed thienyl substitutes, are introduced as the core for constructing dopant‐free hole transporting materials (HTMs). The coplanar π‐extended quinoxaline‐based HTM TQ4 achieves the best photovoltaic performance (exceed 21 %) among planar n‐i‐p structured dopant‐free perovskite solar cells.
Inverted‐structured perovskite solar cells (PSCs) mostly employ poly‐triarylamines (PTAAs) as hole‐transporting materials (HTMs), which generally result in low‐quality buried interface due to their ...hydrophobic nature, shallow HOMO levels, and absence of passivation groups. Herein, the authors molecularly engineer the structure of PTAA via removing alkyl groups and incorporating a multifunctional pyridine unit, which not only regulates energy levels and surface wettability, but also passivates interfacial trap‐states, thus addressing above‐mentioned issues simultaneously. By altering the linking‐site on pyridine unit from ortho‐ (o‐PY) to meta‐ (m‐PY) and para‐position (p‐PY), they observed a gradually improved hydrophilicity and passivation efficacy, mainly owing to increased exposure of the pyridine‐nitrogen as well as its lone electron pair, which enhances the contact and interactions with perovskite. The open‐circuit voltage and power conversion efficiency (PCE) of inverted‐structured PSCs based on these HTMs increased with the same trend. Consequently, the optimal p‐PY as HTM enables facile deposition of uniform perovskite films without complicated interlayer optimizations, delivering a remarkably high PCE exceeding 22% (0.09 cm2). Moreover, when enlarging device area tenfold, a comparable PCE of over 20% (1 cm2) can be obtained. These results are among the highest efficiencies for inverted PSCs, demonstrating the high potential of p‐PY for future applications.
The quality of buried interfaces in inverted perovskite solar cells is improved via constructing hole‐transporting materials with deep HOMO levels, high wetting, and passivation capabilities. By systematically regulating the linking‐site of pyridine unit, high efficiencies exceeding 22% (0.09 cm2) and 20% (1 cm2) are achieved.
Recently LHCb declared a new structure
X
(6900) in the final state di-
J
/
ψ
which is popularly regarded as a
cc
-
c
¯
c
¯
tetraquark state. Within the Bethe–Salpeter (B–S) framework we study the ...possible
cc
-
c
¯
c
¯
bound states and the interaction between diquark (
cc
) and antidiquark (
c
¯
c
¯
). In this work
cc
(
c
¯
c
¯
) is treated as a color anti-triplet (triplet) axial-vector so the quantum numbers of
cc
-
c
¯
c
¯
bound state are
0
+
,
1
+
and
2
+
. Learning from the interaction in meson case and using the effective coupling we suggest the interaction kernel for the diquark and antidiquark system. Then we deduce the B–S equations for different quantum numbers. Solving these equations numerically we find the spectra of some excited states can be close to the mass of
X
(6900) when we assign appropriate values for parameter
κ
introduced in the interaction (kernel). We also briefly calculate the spectra of
bb
-
b
¯
b
¯
bound states. Future measurement of
bb
-
b
¯
b
¯
state will help us to determine the exact form of effective interaction.
The oxygen reduction reaction (ORR) on transition single‐atom catalysts (SACs) is sustainable in energy‐conversion devices. However, the atomically controllable fabrication of single‐atom sites and ...the sluggish kinetics of ORR have remained challenging. Here, we accelerate the kinetics of acid ORR through a direct O−O cleavage pathway through using a bi‐functional ligand‐assisted strategy to pre‐control the distance of hetero‐metal atoms. Concretely, the as‐synthesized Fe−Zn diatomic pairs on carbon substrates exhibited an outstanding ORR performance with the ultrahigh half‐wave potential of 0.86 V vs. RHE in acid electrolyte. Experimental evidence and density functional theory calculations confirmed that the Fe−Zn diatomic pairs with a specific distance range of around 3 Å, which is the key to their ultrahigh activity, average the interaction between hetero‐diatomic active sites and oxygen molecules. This work offers new insight into atomically controllable SACs synthesis and addresses the limitations of the ORR dissociative mechanism.
The dual single‐atom carbon electrocatalysts are rationally optimized for the interatomic distance and promote an effective oxygen reduction reaction via the direct oxygen‐oxygen bond cleavage mechanism in acid electrolyte. The specific distance of dual‐hetero single‐atom pairs weakens and destabilizes the bond energy of the oxygen‐oxygen bond through the strong and evenly bilateral electron and charge transfer capabilities.
Fluorescence-based technologies have revolutionized in vivo monitoring of biomolecules. However, significant technical hurdles in both probe chemistry and complex cellular environments have limited ...the accuracy of quantifying these biomolecules. Herein, we report a generalizable engineering strategy for dual-emission anti-Kasha-active fluorophores, which combine an integrated fluorescein with chromene (IFC) building block with donor-π-acceptor structural modification. These fluorophores exhibit an invariant near-infrared Kasha emission from the S
state, while their anti-Kasha emission from the S
state at around 520 nm can be finely regulated via a spirolactone open/closed switch. We introduce bio-recognition moieties to IFC structures, and demonstrate ratiometric quantification of cysteine and glutathione in living cells and animals, using the ratio (S
/S
) with the S
emission as a reliable internal reference signal. This de novo strategy of tuning anti-Kasha-active properties expands the in vivo ratiometric quantification toolbox for highly accurate analysis in both basic life science research and clinical applications.
Chemiluminescence (CL)‐based technologies have revolutionized in vivo monitoring of biomolecules. However, significant technical hurdles have limited the achievement of trigger‐controlled, bright, ...and enriched CL signal. Herein, a dual‐lock strategy uses sequence‐dependent triggers for bright optical imaging with real‐time fluorescent signal and ultra‐sensitive CL signal. These probes can obtain an analyte‐triggered accumulation of stable pre‐chemiluminophore with aggregation‐induced emission (AIE), and then the pre‐chemiluminophore exhibits a rapid photooxidation process (1,2‐dioxetane generation) by TICT‐based free‐radical addition, thereby achieving an enrichment and bright CL signal. The dual‐lock strategy expands the in vivo toolbox for highly accurate analysis and has for the first time allowed access to accurately sense and trace biomolecules with high‐resolution, dual‐mode of chemo‐fluoro‐luminescence, and three‐dimensional (3D) imaging in living animals.
A dual‐lock strategy by sequence‐dependent triggers is developed for bright optical imaging with the integration of real‐time fluorescence and ultra‐sensitive chemiluminescence (CL) signals. This sequential dual‐lock strategy allows accurate sensing and tracing of biomolecules with high‐resolution, dual‐mode 3D imaging in living animals.
Optical characteristics of luminescent materials, including emission color (wavelength), lifetime, and excitation mode, play crucial roles in data communication and information security. Conventional ...luminescent materials generally display unicolor, unitemporal, and unimodal (occasionally bimodal) emission, resulting in low‐level readout and decoding. The development of multicolor, multitemporal, and multimodal luminescence in a single material has long been considered to be a significant challenge. In this study, for the first time, the superior integration of colorful (red–orange–yellow–green), bitemporal (fluorescent and delayed), and four‐modal (thermo‐/mechano‐motivated and upconverted/downshifted) emissions in a particular piezoelectric particle via optical multiplexing of dual‐lanthanide dopants is demonstrated. The as‐prepared versatile NaNbO3:Pr3+,Er3+ luminescent microparticles shown are particularly suitable for embedding into polymer films to achieve waterproof, flexible/wearable and highly stretchable features, and synchronously to provide multidimensional codes that can be visually read‐out using simple and commonly available tools (including the LED of a smartphone, pen writing, cooling–heating stimuli, and ultraviolet/near‐infrared lamps). These findings offer unique insight for designing highly integrated stimuli‐responsive luminophors and smart devices toward a wide variety of applications, particularly advanced anticounterfeiting technology.
Thermo‐mechano‐opto‐responsive bitemporal (fluorescent and delayed) colorful (red–orange–yellow–green) luminescence is designed and achieved through optical multiplexing of dual‐lanthanides of Pr3+ and Er3+ in NaNbO3 piezoelectric microparticles. The smart materials are well‐embedded into polymer elastomers to show waterproof, flexible/wearable and highly‐stretchable features, and provide multidimensional codes that enable visual readout using commonly available tools (e.g., smartphone flashlight, pen writing, and cooling‐heating stimuli).
PDF
