Nitrate electrocatalytic reduction (NO3RR) for ammonia production is a promising strategy to close the N‐cycle from nitration contamination, as well as an alternative to the Haber–Bosch process with ...less energy consumption and carbon dioxide release. However, current long‐term stability of NO3RR catalysts is usually tens of hours, far from the requirements for industrialization. Here, symmetry‐broken Cusingle‐atom catalysts are designed, and the catalytic activity is retained after operation for more than 2000 h, while an average ammonia production rate of 27.84 mg h−1 cm−2 at an industrial level current density of 366 mA cm−2 is achieved, obtaining a good balance between catalytic activity and long‐term stability. Coordination symmetry breaking is achieved by embedding one Cu atom in graphene nanosheets with two N and two O atoms in the cis‐configuration, effectively lowering the coordination symmetry, rendering the active site more polar, and accumulating more NO3− near the electrocatalyst surface. Additionally, the cis‐coordination splits the Cu 3d orbitals, which generates an orbital‐symmetry‐matched π‐complex of the key intermediate *ONH and reduces the energy barrier, compared with the σ‐complex generated with other catalysts. These results reveal the critical role of coordination symmetry in single‐atom catalysts, prompting the design of more coordination‐symmetry‐broken electrocatalysts toward possible industrialization.
A coordination‐symmetry‐breaking Cusingle‐atom catalyst enables a good balance between catalytic activity and long‐term stability in nitrate electroreduction to ammonia. The catalytic activity is retained after operation for more than 2000 h, while an average ammonia production rate of 27.84 mg h−1 cm−2 at an industrial level current density of 366 mA cm−2 is achieved.
A
bstract
We obtain the complete and independent bases of effective operators at mass dimension 5, 6, 7, 8, 9 in both standard model effective field theory with light sterile right-handed neutrinos (
...ν
SMEFT) and low energy effective field theory with light sterile neutrinos (
ν
LEFT). These theories provide systematical parametrizations on all possible Lorentz-invariant physical effects involving in the Majorana/Dirac neutrinos, with/without the lepton number violations. In the
ν
SMEFT, we find that there are 2 (18), 29 (1614), 80 (4206), 323 (20400), 1358 (243944) independent operators with sterile neutrinos included at the dimension 5, 6, 7, 8, 9 for one (three) generation of fermions, while 24, 5223, 3966, 25425, 789426 independent operators in the
ν
LEFT for two generations of up-type quarks and three generations of all other fermions.
We present a complete and independent list of the dimension-nine operator basis in the Standard Model effective field theory by an automatic algorithm based on the amplitude-operator correspondence. ...A complete basis (Y-basis) is first constructed by enumerating the Young tableau of an auxiliary SU(N) group and the gauge groups, with the equation-of-motion and integration-by-part redundancies all removed. In the presence of repeated fields, another basis (P-basis) with explicit flavor symmetries among them is derived from the Y-basis, which further induces a basis of independent monomial operators through a systematic process called desymmetrization. Our form of operators has advantages over the traditional way of presenting operators constrained by flavor relations, in the simplicity of both eliminating flavor redundancies and identifying independent flavor-specified operators. We list the 90456 (560) operators for three (one) generations of fermions, all of which violate baryon number or lepton number conservation; among them we find new violation patterns as ΔB = 2 and ΔL = 3, which only appear at the dimensions d ≥ 9.
A
bstract
We consider extended scalar sectors of the Standard Model as ultraviolet complete motivations for studying the effective Higgs self-interaction operators of the Standard Model effective ...field theory. We investigate all motivated heavy scalar models which generate the dimension-six effective operator, |
H
|
6
, at tree level and proceed to identify the full set of tree-level dimension-six operators by integrating out the heavy scalars. Of seven models which generate |
H
|
6
at tree level only two, quadruplets of hypercharge
Y
= 3
Y
H
and
Y
=
Y
H
, generate only this operator. Next we perform global fits to constrain relevant Wilson coefficients from the LHC single Higgs measurements as well as the electroweak oblique parameters
S
and
T
. We find that the
T
parameter puts very strong constraints on the Wilson coefficient of the |
H
|
6
operator in the triplet and quadruplet models, while the singlet and doublet models could still have Higgs self-couplings which deviate significantly from the standard model prediction. To determine the extent to which the |
H
|
6
operator could be constrained, we study the di-Higgs signatures at the future 100 TeV collider and explore future sensitivity of this operator. Projected onto the Higgs potential parameters of the extended scalar sectors, with 30 ab
−1
luminosity data we will be able to explore the Higgs potential parameters in all seven models.
A
bstract
We obtain the complete operator bases at mass dimensions 5, 6, 7, 8, 9 for the low energy effective field theory (LEFT), which parametrize various physics effects between the QCD scale and ...the electroweak scale. The independence of the operator basis regarding the equation of motion, integration by parts and flavor relations, is guaranteed by our algorithm 1, 2, whose validity for the LEFT with massive fermions involved is proved by a generalization of the amplitude-operator correspondence. At dimension 8 and 9, we list the 35058 (756) and 704584 (3686) operators for three (one) generations of fermions categorized by their baryon and lepton number violations (∆
B
, ∆
L
), as these operators are of most phenomenological relevance.
We report phase-programmable Gaussian boson sampling (GBS) which produces up to 113 photon detection events out of a 144-mode photonic circuit. A new high-brightness and scalable quantum light source ...is developed, exploring the idea of stimulated emission of squeezed photons, which has simultaneously near-unity purity and efficiency. This GBS is programmable by tuning the phase of the input squeezed states. The obtained samples are efficiently validated by inferring from computationally friendly subsystems, which rules out hypotheses including distinguishable photons and thermal states. We show that our GBS experiment passes a nonclassicality test based on inequality constraints, and we reveal nontrivial genuine high-order correlations in the GBS samples, which are evidence of robustness against possible classical simulation schemes. This photonic quantum computer, Jiuzhang 2.0, yields a Hilbert space dimension up to ∼ 1043, and a sampling rate ∼ 1024 faster than using brute-force simulation on classical supercomputers.
To remedy the drawbacks of weak solar‐thermal conversion capability, low thermal conductivity, and poor structural stability of phase change materials, pyramidal graphitized chitosan/graphene ...aerogels (G‐CGAs) with numerous radially oriented layers are constructed, in which the long‐range radial alignment of graphene sheets is achieved by a novel directional‐freezing strategy. A G‐CGA/polyethylene glycol phase change composite exhibits a thermal conductivity of 2.90 W m−1 K−1 with a latent heat of 178.8 J g−1, and achieves a superior solar‐thermal energy conversion and storage efficiency of 90.4% and an attractive maximum temperature of 99.7 °C under a light intensity of 200 mW cm−2. Inspired by waterlilies, solar‐responsive phase change composites (SPCCs) are designed for the first time by assembling the G‐CGA/polyethylene glycol phase change composites with solar‐driven bilayer films, which bloom by day and close by night. The heat preservation effect of the solar‐driven films leads to a higher temperature of SPCC for a longer period at night. The SPCC‐based solar–thermal–electric generator achieves output voltages of 499.2 and 1034.9 mV under light intensities of 200 and 500 mW cm−2, respectively. Even after stopping the solar irradiation, the voltage output still occurs because of the latent heat release and the heat preservation of the films.
Pyramidal graphene aerogels with radial structures are prepared by a novel directional‐freezing strategy as thermally conductive skeletons for solar‐thermal phase change composites. Inspired by waterlilies, solar‐responsive phase change composites are designed for the first time, which can bloom during daytime for solar‐thermal conversion and close at night to reduce heat loss. Assembled solar‐thermal‐electric generator achieves high output‐voltages under solar‐light irradiation.
We present a complete list of the dimension-eight operator basis in the standard model effective field theory using group theoretic techniques in a systematic and automated way. We adopt a new form ...of operators in terms of the irreducible representations of the Lorentz group and identify the Lorentz structures as states in a SU(N) group. In this way, redundancy from equations of motion is absent and that from integration by part is treated using the fact that the independent Lorentz basis forms an invariant subspace of the SU(N) group. We also decompose operators into the ones with definite permutation symmetries among flavor indices to deal with subtlety from repeated fields. For the first time to our knowledge, we provide the explicit form of independent flavor-specified operators in a systematic way. Our algorithm can easily be applied to higher-dimensional standard model effective field theory and other effective field theories, making these studies more approachable.
Quantum computers promise to perform certain tasks that are believed to be intractable to classical computers. Boson sampling is such a task and is considered a strong candidate to demonstrate the ...quantum computational advantage. We performed Gaussian boson sampling by sending 50 indistinguishable single-mode squeezed states into a 100-mode ultralow-loss interferometer with full connectivity and random matrix-the whole optical setup is phase-locked-and sampling the output using 100 high-efficiency single-photon detectors. The obtained samples were validated against plausible hypotheses exploiting thermal states, distinguishable photons, and uniform distribution. The photonic quantum computer,
, generates up to 76 output photon clicks, which yields an output state-space dimension of 10
and a sampling rate that is faster than using the state-of-the-art simulation strategy and supercomputers by a factor of ~10
.
Abstract
The demand for sustainable energy has motivated the development of artificial photosynthesis. Yet the catalyst and reaction interface designs for directly fixing permanent gases (e.g. CO
2
, ...O
2
, N
2
) into liquid fuels are still challenged by slow mass transfer and sluggish catalytic kinetics at the gas-liquid-solid boundary. Here, we report that gas-permeable metal-organic framework (MOF) membranes can modify the electronic structures and catalytic properties of metal single-atoms (SAs) to promote the diffusion, activation, and reduction of gas molecules (e.g. CO
2,
O
2
) and produce liquid fuels under visible light and mild conditions. With Ir SAs as active centers, the defect-engineered MOF (e.g. activated NH
2
-UiO-66) particles can reduce CO
2
to HCOOH with an apparent quantum efficiency (AQE) of 2.51% at 420 nm on the gas-liquid-solid reaction interface. With promoted gas diffusion at the porous gas-solid interfaces, the gas-permeable SA/MOF membranes can directly convert humid CO
2
gas into HCOOH with a near-unity selectivity and a significantly increased AQE of 15.76% at 420 nm. A similar strategy can be applied to the photocatalytic O
2
-to-H
2
O
2
conversions, suggesting the wide applicability of our catalyst and reaction interface designs.
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