Search

Sub-10 nm anatase TiO2 nanoparticle-modified Pt nanoclusters were constructed as highly-efficient photocatalysts for H2 production from lignocellulosic biomass, including rice straw, corncob, polar wood chip, bamboo, rice hull and wheat straw.

Funding Information: This research was supported in part by the National Natural Science Foundation of China under Grant No. 61901136, the National Key Research and Development Program of China under Grant No. 2021YFC2801204, the Ph.D. Student Research and Innovation Fund of the Fundamental Research Funds for the Central Universities under Grant No. 3072021GIP0507, and the China Scholarship Council under Grant No. 202006680029. The authors would like to thank the Acoustic Research Laboratory of the National University of Singapore for providing the snapping shrimp noise. The authors also thank Mandar Chitre, the head of the Acoustic Research Laboratory, for his helpful comments to improve the manuscript. Publisher Copyright: © 2022 Acoustical Society of America. Detecting the presence or absence of a known signal is an important aspect of underwater acoustic (UWA) communications as it is a vital first step to process the received data. The influence of impulsive noise and multipath propagation on detection are both considered in this paper. Many robust detectors have been designed to cope with impulsive noise, but they tend to ignore the impact of multipath propagation, which may decrease the detection probability. To emphasize the role of multipath channel, we propose two-stage detection methods. In the first stage, the channel is estimated based on robust orthogonal matching pursuit, while in the second stage, detectors that use the channel estimation from the first stage, namely augmented log-likelihood ratio detector and augmented pseudo-correlation detector, are developed. The former detector is parametric and the latter one is non-parametric. The improved performance is demonstrated in simulated multipath channel and actual UWA channel with both simulated noiseand recorded snapping shrimp noise, indicating that the proposed detectors are resistant to impulsive noise. It is also shown that the use of multipath information helps to improve the detection performance.

Dual-cylinder driving columns of a hydraulic support are required to be synchronous, with the purpose of guaranteeing the support balance and providing the roof an enough force. In addition, pipelines connecting cylinders with electro-hydraulic servo-valve have a significance influence on synchronization. Taking the length of pipelines into account, the mathematical model of a dual-cylinder driven hydraulic support is built, and the displacement–force coupling characteristic caused by the shared pump is tackled by a decoupling compensator. Following that, an adaptive sliding-mode synchro-position control strategy (ASSC) is designed based on an improved sliding mode reaching law and an adaptive law is developed to restrain the uncertainties resulted from the sub-system after decoupling. The experimental results obtained from the joint simulation platform and practical system show that the proposed controller can effectively reduce the synchronization error between two column positions and has better control performance than the PI and fuzzy PID controllers.

Adsorption and activation of dinitrogen (N2) is an indispensable process in nitrogen fixation. Metal nitride species continue to attract attention as a promising catalyst for ammonia synthesis. However, the detailed mechanisms at a molecular level between reactive nitride species and N2 remain unclear at elevated temperature, which is important to understand the temperature effect and narrow the gap between the gas phase system and condensed phase system. Herein, the 14N/15N isotopic exchange in the reaction between tantalum nitride cluster anions Ta314N3− and 15N2 leading to the regeneration of 14N2/14N15N was observed at elevated temperature (393−593 K) using mass spectrometry. With the aid of theoretical calculations, the exchange mechanism and the effect of temperature to promote the dissociation of N2 on Ta3N3− were elucidated. A comparison experiment for Ta314N4−/15N2 couple indicated that only desorption of 15N2 from Ta314N415N2− took place at elevated temperature. The different exchange behavior can be well understood by the fact that nitrogen vacancy is a requisite for the dinitrogen activation over metal nitride species. This study may shed light on understanding the role of nitrogen vacancy in nitride species for ammonia synthesis and provide clues in designing effective catalysts for nitrogen fixation.

The increasingly stringent emission regulations make it urgent to get a fundamental understanding on the catalytic behaviors of rhodium, the most efficient component in three-way catalysts (TWCs) to convert NOx into N2. Herein, the catalytic conversion of NO and CO into N2 and CO2 by gas-phase rhodium-aluminum oxide species (RhAlO0–3 and RhAl2O1–4) was identified by mass spectrometry and quantum chemical calculations. This finding represents a significant step in the field of gas-phase catalysis, given that only elementary reactions for this conversion are commonly observed because it is extremely challenging to rupture the strong N–O bond and couple the N–N bond as well as drive the resulting product to oxidize CO. It emphasized that a polarized Rh–Al bond in gas-phase species is indispensable and the RhAlO0,1 and RhAl2O1,2 species with direct Rh–Al bonding can be involved in catalytic NO reduction by CO.

The liberation of a single D atom in N2 activation by gas-phase clusters was identified for the first time in the reactions of Ta2D2,4− with N2, and Ta2D4− is much more reactive than Ta2D2−.

We experimentally identify the gas-phase species Rh2− that can drive the reverse water–gas shift (RWGS, CO2 + H2 → CO + H2O) reaction. The generation of a gas-phase H2O molecule and [Rh2(CO)ads]− at room temperature was identified and the only elementary step that requires extra energy to complete the catalysis is CO desorption.

A possible N–C bond formation directly from N2 and CH4 mediated by heteronuclear metal cluster anions CoTaC2− at room temperature was identified.

TiO2 nanoparticles grown on MoS2/N-doped graphitic carbon were demonstrated to be efficient noble-metal-free photocatalysts for H2 production from lignocellulosic biomass, and the H2 generation rate from wheat straw, corncob, polar...

Some nanosystems based on carbon nanomaterials have been used for fluorescent chemical/biosensing, elementary information processing, and textual coding. However, little attention has been paid to utilizing biowaste-derived carbon nanomaterials for colorimetric multi-channel sensing and advanced molecular information protection (including text and pattern information). Herein, fish scale-derived carbon nanoparticles (FSCN) were prepared and used for colorimetric detection of metal ions, encoding, encrypting and hiding text- and pattern-based information. The morphology and composition of FSCN were analyzed by TEM, XRD, FTIR, and XPS, and it was found that the FSCN-based multi-channel colorimetric sensing system can detect Cr

A high-temperature linear ion trap that can stably run up to 873 K was newly designed and installed into a homemade reflectron time-of-flight mass spectrometer coupled with a laser ablation cluster source and a quadrupole mass filter. The instrument was used to study the pyrolysis behavior of mass-selected (V

Fundamental understanding of the nature of active sites in real-life water gas shift (WGS) catalysts that can convert CO and H2O into CO2 and H2 is crucial to engineer related catalysts performing under ambient conditions. Herein, we identified that the WGS reaction can be, in principle, catalyzed by rhodium-manganese oxide clusters Rh2MnO1,2- in the gas phase at room temperature. This is the first example of the construction of such a potential catalysis in cluster science because it is challenging to discover clusters that can abstract the oxygen from H2O and then supply the anchored oxygen to oxidize CO. The WGS reaction was characterized by mass spectrometry, photoelectron spectroscopy, and quantum-chemical calculations. The coordinated oxygen in Rh2MnO1,2- is paramount for the generation of an electron-rich Mn+-Rh- bond that is critical to capture and reduce H2O and giving rise to a polarized Rh+-Rh- bond that functions as the real redox center to drive the WGS reaction.

As an alternative strategy for H2 production under ambient conditions, solar-driven lignocellulose-to-H2 conversion provides a very attractive approach to store and utilize solar energy sustainably. Exploiting efficient photocatalyst for photocatalytic lignocellulose-to-H2 conversion is of huge significance and remains the key challenge for development of solar H2 generation from lignocellulose. Herein, 2D-2D MoS2 /TiO2 photocatalysts with large 2D nanojunction were constructed for photocatalytic lignocellulose-to-H2 conversion. In this smart structure, the 2D nanojunctions acted as efficient channel for charge transfer from TiO2 to MoS2 to improve charge separation efficiency and thus enhance photocatalytic lignocellulose-to-H2 conversion activity. The 2 % MoS2 /TiO2 photocatalyst showed the highest photocatalytic lignocellulose-to-H2 conversion performance with the maximal H2 generation rate of 201 and 21.4 μmol h-1 g-1 in α-cellulose and poplar wood chip aqueous solution, respectively. The apparent quantum yield at 380 nm reached 1.45 % for 2 % 2D-2D TiO2 /MoS2 photocatalyst in α-cellulose aqueous solution. This work highlights the importance of optimizing the interface structures of photocatalyst for solar-driven lignocellulose-to-H2 conversion.

A Z-scheme system was successfully constructed for visible-light-driven photocatalytic H2 production from lignocelluloses, the highest H2 evolution rate of this Z-scheme system is 5.3 and 1.6 μmol h-1 in α-cellulose and poplar wood chip aqueous solutions, respectively, under visible light irradiation.

It is of great importance to study the mechanisms to activate dinitrogen (N2), the very inert molecule, under mild conditions. Gas-phase metal clusters are being actively generated to react with N2 to identify new reaction types and mechanisms. Herein, an unprecedented, mechanistically unique metal atom (Fe or V) ejection in the thermal reaction of FeV2C2- with N2 has been identified using mass spectrometry, photoelectron imaging spectroscopy, and quantum chemistry calculations. Strong evidence suggests that the complete cleavage of the N≡N triple bond and subsequent functionalization of two N atoms via C-N coupling were achieved in this reaction. The complementary cooperation between V atoms with strong electron-donating ability and an Fe atom with large electron-withdrawing ability as well as the geometric flexibility of the Fe-V-V ring drives the whole reaction. The important role of C ligands in N≡N cleavage was also revealed. This study emphasizes the importance of heteronuclear metal systems for N2 fixation.

Photoassisted steam reforming and dry (CO2 ) reforming of methane (SRM and DRM) at room temperature with high syngas selectivity have been achieved in the gas-phase catalysis for the first time. The catalysts used are bimetallic rhodium-vanadium oxide cluster anions of Rh2 VO1-3 - . Both the oxidation of methane and reduction of H2 O/CO2 can take place efficiently in the dark while the pivotal step to govern syngas selectivity is photo-excitation of the reaction intermediates Rh2 VO2,3 CH2 - to specific electronically excited states that can selectively produce CO and H2 . Electronic excitation over Rh2 VO2,3 CH2 - to control the syngas selectivity is further confirmed from the comparison with the thermal excitation of Rh2 VO2,3 CH2 - , which leads to diversity of products. The atomic-level mechanism obtained from the well-controlled cluster reactions provides insight into the process of selective syngas production from the photocatalytic SRM and DRM reactions over supported metal oxide catalysts.

Cleavage of the triple N≡N bond by metal clusters is of fundamental interest and practical importance in nitrogen fixation. Previous studies of N≡N bond cleavage by gas-phase metal clusters emphasized the importance of the dinuclear metal centers. Herein, the dissociative adsorption of N2 and subsequent C-N coupling on trinuclear carbide cluster anions V3C4- under thermal collision conditions have been characterized by employing mass spectrometry (collision induced dissociation), cryogenic photoelectron imaging spectroscopy, and quantum chemistry calculations. A theoretical analysis identified a crucial adsorption intermediate with N2 bonded with the V3 metal core in the end-on/side-on/side-on (ESS) mode, which most likely enables the facile cleavage of the N≡N bond. Such a vital N2 coordination in the ESS mode is a result of symmetry-matched interactions between the occupied orbitals of the metal core and both of the two empty π* orbitals of N2. Furthermore, carbon ligands also play a considerable role in enhancing the reactivity of the metal core toward N2. This study strongly suggests a new mechanism of N≡N bond cleavage by gas-phase metal clusters.

Nitrogen (N

Plasmonic materials have been widely used in chemo/biosensing and biomedicine. However, little attention has been paid to the application of plasmonic materials in terms of the transition from molecular sensing to molecular informatization. Herein, we demonstrated that silver nanoparticles (AgNPs) prepared through facile and rapid microwave heating have multimode colorimetric sensing capabilities to different metal ions (Cr

Peptides have higher information density than DNA and equivalent molecular recognition ability and durability. However, there are currently no reports on the comprehensive use of peptides' recognition ability and structural diversity for sensing, logic computing, information coding, and protection. Herein, we, for the first time, demonstrate peptide-based sensing, logic computing, and information security on the antimonene platform. The molecular recognition capability and structural diversity (amino acid sequence) of peptides (Pb

Inspired by information processing and communication in nature based on molecular recognition and structural diversity, ongoing efforts aim to development of artificial molecular or nano-systems for sensing, logic computing, and even data storage and safety. However, due to their preparation/functionalization shortcomings (laborious and time-consuming), poor flexibility and compatibility, and limited paradigm, it is still a big challenge whether simple molecules can be used to achieve comprehensive and universal applications from sensing to information storage and protection. Herein, we for the first time demonstrated a molecular paradigm-computer-like "basic input output system (BIOS)" which can realize "plug-and-play" sensing, information encoding, molecular cryptography, and steganography based on a simple artificial molecule (p-nitrophenol, PNP). Based on its molecular recognition and inherent chemical identities, PNP was utilized for colorimetric detection of multiple metal ions (Hg

Cleavage of the strong N≡N bond has long been a great challenge for energy-efficient dinitrogen (N

Inspired by information exchange and logic functions of life based on molecular recognition and interaction networks, ongoing efforts are directed toward development of molecular or nanosystems for multiplexed chem/biosensing and advanced information processing. However, because of their preparation shortcomings, poor functionality, and limited paradigms, it is still a big challenge to develop advanced nanomaterials-based systems and comprehensively realize neuron-like functions from multimode sensing to molecular information processing and safety. Herein, using fish scales derived carbon nanoparticles (FSCN) as a reducing agent and stabilizer, a simple one-step synthesis method of multifunctional silver-carbon nanocomposites (AgNPs-FSCN) is developed. The prepared AgNPs-FSCN own wide antibacterial and multisignal response abilities in five channels (including color, Tyndall, absorption and fluorescence intensities, and absorption wavelength) for quantitative colorimetric and fluorescence sensing of H2 O2 , ascorbic acid, and dopamine. Benefiting from its multicoding stimuli-responsive ability, molecular concealment, and programmability, AgNPs-FSCN can be abstracted as nanoneurons for implementing batch and parallel molecular logic computing, steganography, and cryptography. This research will promote the preparation of advanced multifunctional nanocomposites and the development of their multipurpose applications, including the multireadout-guided multianalyte intelligent sensing and sophisticated molecular computing, communication, and security.

The heterogeneous oxidation of isoprene (C5H8) by metal-oxide particles, such as the typical mineral aerosols TiO2, plays an important role in the isoprene atmospheric chemistry. However, the underlying mechanism of C5H8 oxidation remains elusive owing to the complexities of aerosol surfaces and reaction channels. Herein, we report the gas-phase reactions of TixOy+ (x = 1-7, y = 1-14) cations with isoprene by using mass spectrometry and density functional theory (DFT) calculations. Five types of reaction channels were observed: association, hydrogen atom transfer (HAT), C-C bond cleavage, combined oxygen atom transfer (OAT) and HAT and combined OAT and C-C bond cleavage. It is noteworthy that formaldehyde is known as the major oxidation product of isoprene/hydroxyl radicals in the atmosphere. In addition, CO has not been observed in the reactions of isoprene with gas-phase ions. Therefore, the reaction mechanisms of CH2O and CO generation observed in Ti2O5+/C5H8 and Ti4O8+/C5H8 systems were further investigated by DFT calculations, and the calculated results are in agreement with the experimental observations. In these two reactions, both Ti and O atoms can be the adsorption sites for C5H8. The reaction channels and mechanistic information gained in these gas-phase model reactions may offer fundamental insights relevant to the corresponding oxidation processes over titanium oxide aerosols in the atmosphere.

The side-on-end-on coordination of N2 can be very important to activate and functionalize this very stable molecule. However, such coordination has rarely been reported. This study reports a gas-phase species (a polynuclear vanadium nitride cluster anion [V5 N5 ]- ) that can capture N2 efficiently (12 %), and the quantum chemistry modelling suggests an unusual side-on-end-on coordination. The cluster anions were generated by laser ablation and the reaction with N2 has been characterized by mass spectrometry, photoelectron imaging spectroscopy, and density functional theory calculations. The back-donation interactions between the localized d-d bonding orbitals on the low-coordinated dual metal (V) sites and the antibonding π* orbitals of N2 are the driving forces to adsorb N2 with a high binding energy (about 2.0 eV).

Understanding the heterogeneous oxidation of isoprene is crucial to discover the missing sink of the atmospheric isoprene. Iron oxide nanoparticles dominate the most abundant type of anthropogenic ...

Dinitrogen activation and reduction is one of the most challenging and important subjects in chemistry. Herein, we report the N2 binding and reduction at the well-defined Ta3N3H– and Ta3N3– gas-pha...

Dinitrogen (N2) activation by metal hydride species is of fundamental interest and practical importance while the role of hydrogen in N2 activation is not well studied. Herein, the structures of Co3Dn− (n = 0–4) clusters and their reactions with N2 have been studied by using a combined experimental and computational approach. The mass spectrometry experiments identified that the Co3Dn− (n = 2–4) clusters could adsorb N2 while the Co3Dn− (n = 0 and 1) clusters were inert. The photoelectron imaging spectroscopy indicated that the electron detachment energies of Co3D2–4− are smaller than those of Co3D0,1−, which characterized that it is easier to transfer electrons from Co3D2–4− than from Co3D0,1− to activate N2. The density functional theory calculations generally supported the experimental observations. Further analysis revealed that the H atoms in the Co3Hn− (n = 2–4) clusters generally result in higher energies of the Co 3d orbitals in comparison with the Co3Hn− (n = 0 and 1) systems. By forming chemical bonds with H atoms, the Co atoms of Co3H2–4− are less negatively charged with respect to the naked Co3− system, which leads to higher N2 binding energies of Co3H2–4N2− than that of Co3N2−.

The construction of C–N bonds by the direct incorporation of dinitrogen (N2) instead of ammonia (NH3) into active species is particularly desirable but has been rarely reported. Herein, a ditantalu...