Organic-inorganic halide perovskites (OIHPs) are recognized as the promising next-generation X-ray detection materials. However, the device performance is largely limited by the ion migration issue of OIHPs. Here, we reported a simple atomistic surface passivation strategy with methylammonium iodide (MAI) to remarkably increase the ion migration activation energy of CH3NH3PbI3 single crystals. The amount of MAI deposited on the crystal surface is finely regulated by a self-assemble process to effectively suppress the metallic lead defects, while not introducing extra mobile ions, which results in significantly improved dark current stability of the coplanar-structure devices under a large electric field of 100 V mm-1. The X-ray detectors hence exhibit a record-high sensitivity above 700,000 μC Gyair‐1 cm‐2 under continuum X-ray irradiation with energy up to 50 keV, which enables an ultralow X-ray detection limit down to 1.5 nGyair s-1. Our findings will allow for the dramatically reduced X-ray exposure of human bodies in medical imaging applications.

Nanostructures have attracted increasing interest for applications in electrolysis of water as electrocatalysts. In this work, the edge-catalytic effects of one dimensional (1D) VS2 nanoribbons with various edge configurations and widths have been investigated based on first-principles calculations. We show that the catalytic ability of VS2 nanoribbons strongly depends on their edge structure, edge configuration, and width. We find that the S-edges of VS2 nanoribbons are more active in electrolysis of water than V-edges due to their optimal Gibbs free energy for hydrogen evolution reaction in a wider range of hydrogen coverages. We also find that narrow nanoribbons show better catalytic performance than their wide counterparts. We further show that the S-edge of narrow VS2 nanoribbons with their V-edge covered by eight sulfur atoms has near-zero Gibbs free energy of hydrogen adsorption and comparable catalytic performance with Pt to a wide range of hydrogen coverage, which is contributed to its metallic characteristic. We expect that VS2 nanoribbons would be a promising 1D catalyst in electrolysis of water because of their impressive catalytic abilities both on the basal planes and edges.

We investigate nonclassical properties of the field states generated by subtracting any number photon from the squeezed thermal state (STS). It is found that the normalization factor of photon-subtracted STS (PSSTS) is a Legendre polynomial of squeezing parameter r and average photon numbern of thermal state. Expressions of several quasi-probability distributions of PSSTS are derived analytically. Furthermore, the nonclassicality is discussed in terms of the negativity of Wigner function (WF). It is shown that the WF of single PSSTS always has negative values ifn < sinh 2 r at the phase space center. The decoherence effect on PSSTS is then included by analytically deriving the time evolution of WF. The results show that the WF of single PSSTS has negative value if 2κt < ln{1 − (2n + 1)(n − sinh 2 r)/[(2N + 1)(n cosh 2r + sinh 2 r)]}, which is dependent not only on average number N of environment, but also onn and r.

No abstract

Low-cost, efficient and stable electrocatalysts are required for large-scale production of hydrogen by industrial scale water electrolysis. We report here a hybrid bifunctional electrocatalyst, composed of amorphous NiFe LDH nanosheets...

No abstract

No abstract

We present a scheme for implementing the unconventional geometric two-qubit phase gate with nonzero dynamical phase by using the two-channel Raman interaction of two atoms in a cavity. We show that the dynamical phase acquired in a cyclic evolution is proportional to the geometric phase acquired in the same cyclic evolution, hence the the total phase possesses the same geometric features as the geometric phase. In our scheme the atomic excited state is adiabatically eliminated and the operation of the proposed logic gate involves only in the metastable states of the atom and hence is not affected by spontaneous emission.