Henan Normal University

About: Henan Normal University is a education organization based out in Xinxiang, China. It is known for research contribution in the topics: Catalysis & Ionic liquid. The organization has 10863 authors who have published 11077 publications receiving 166773 citations.

Squeezed optomechanics with phase-matched amplification and dissipation.

Abstract: We investigate the nonlinear interaction between a squeezed cavity mode and a mechanical mode in an optomechanical system (OMS) that allows us to selectively obtain either a radiation-pressure coupling or a parametric-amplification process. The squeezing of the cavity mode can enhance the interaction strength into the single-photon strong-coupling regime, even when the OMS is originally in the weak-coupling regime. Moreover, the noise of the squeezed mode can be suppressed completely by introducing a broadband-squeezed vacuum environment that is phase matched with the parametric amplification that squeezes the cavity mode. This proposal offers an alternative approach to control the OMS using a squeezed cavity mode, which should allow single-photon quantum processes to be implemented with currently available optomechanical technology. Potential applications range from engineering single-photon sources to nonclassical phonon states.

Orbital Interactions in Bi-Sn Bimetallic Electrocatalysts for Highly Selective Electrochemical CO2 Reduction toward Formate Production

Abstract: DOI: 10.1002/aenm.201802427 conversion technologies with renewable but intermittent sources of energy such as wind and solar power.[8,9] However, CO2RR in general is difficult due to CO2 being thermodynamically stable,[10,11] resulting in very sluggish reaction kinetics and huge activation overpotentials during electroreduction. Additionally, the conversion of CO2 competes against other reactions such as the hydrogen evolution reaction (HER) which usually significantly decreases the formation of reduced carbon products. One interesting product which results from CO2 conversion is formate, which is a stable nontoxic liquid that has a large market potential in various applications including hydrogen carrier systems[12–14] and formic acid fuel cells.[15,16] However, highly active, selective, and stable electrocatalysts are still required to facilitate CO2RR to overcome large energy barriers and shift reaction pathways toward formate formation. Based on previously reported studies, most metal-based catalysts such as Au,[17,18] Ag,[19–21] and Ni[22,23] were shown to demonstrate a low selectivity toward the formation of formate, favoring the conversion of CO2 to CO, while Cu was demonstrated to produce a variety of hydrocarbons and alcohols at low Faradaic efficiencies (FE).[24–28] Interestingly, Pd,[29–31] Sn,[32–36] Bi,[37–40] In,[41] and Pb,[28] on the other hand, have demonstrated relatively high selectivity for formate production. Pd shows high selectivity with relatively low overpotentials, but it is too expensive for large-scale CO2 reduction systems. Meanwhile, In and Pb are known to be toxic and not environmentally friendly, which leaves Sn and Bi as good candidates for formate producing catalysts. These metals, being comparatively inexpensive and environmentally benign, are also interesting as electrode materials for large-scale CO2 reduction systems to be integrated into smart energy-grids.[42,43] In terms of catalyst composition, combining more than one element in the form of binary or multicomponent catalysts has shown to be an effective approach to tune the selectivity of CO2RR catalysts.[44–49] However, a wide range of Faradaic efficiencies for formate production (FEformate) from 40% to 99% have been reported on various binary Sn-based electrodes. Improved FEformate has been observed with binary Sn-based catalysts containing Pd,[44] A highly selective and durable electrocatalyst for carbon dioxide (CO2) conversion to formate is developed, consisting of tin (Sn) nanosheets decorated with bismuth (Bi) nanoparticles. Owing to the formation of active sites through favorable orbital interactions at the Sn-Bi interface, the Bi-Sn bimetallic catalyst converts CO2 to formate with a remarkably high Faradaic efficiency (96%) and production rate (0.74 mmol h−1 cm−2) at −1.1 V versus reversible hydrogen electrode. Additionally, the catalyst maintains its initial efficiency over an unprecedented 100 h of operation. Density functional theory reveals that the addition of Bi nanoparticles upshifts the electron states of Sn away from the Fermi level, allowing the HCOO* intermediate to favorably adsorb onto the Bi-Sn interface compared to a pure Sn surface. This effectively facilitates the flow of electrons to promote selective and durable conversion of CO2 to formate. This study provides sub-atomic level insights and a general methodology for bimetallic catalyst developments and surface engineering for highly selective CO2 electroreduction.

Photocatalytic degradation of fluoroquinolone antibiotics using ordered mesoporous g-C3N4 under simulated sunlight irradiation: Kinetics, mechanism, and antibacterial activity elimination

Abstract: The occurrence of fluoroquinolones (FQs) in the ambient environment has raised serious concerns. In this study, the photocatalytic degradation kinetics and mechanism of ciprofloxacin (CIP) was investigated in ordered mesoporous g-C3N4 (ompg-C3N4). Under simulated sunlight irradiation, ompg-C3N4 exhibited a 2.9 fold more rapid reaction for CIP degradation than bulk g-C3N4. This enhancement may be attributed to the large specific surface area and effective charge separation of ompg-C3N4. The eradication of CIP followed the Langmuir–Hinshelwood (L–H) kinetics model, and surface reactions played a significant role during the photocatalysis process. Further study of reactive species (RSs) by both ESR technology and RSs scavenging experiments revealed that the superoxide anion radical (O2 −) and photohole (h+) were primarily responsible for the degradation of CIP. Based on the identification of intermediates using liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), and the prediction of reactive sites via Frontier Electron Densities (FEDs), the degradation pathways of CIP were proposed. A comparison of the degradation among FQs revealed that the piperazine moiety showed a dramatic effect on the degradation of FQs during the photocatalysis process. A residual antibiotic activity experiment revealed that ompg-C3N4 provided a very desirable performance for the reduction of antibiotic activity. The sufficient photocatalytic degradation of CIP in ambient water revealed that a sunlight-driven ompg-C3N4 photocatalytic process may be efficiently applied for the remediation of CIP contaminated natural waters.