Nonreciprocal routing of microwave photons with broad bandwidth via magnon-cavity chiral coupling.

We propose a scheme for realizing nonreciprocal microwave photon routing with two cascaded magnon-cavity coupled systems, which work around the exceptional points of a parity-time (PT)-symmetric Hamiltonian. An almost perfect nonreciprocal transmission can be achieved with a broad bandwidth, where the transmission for a forward-propagating photon can be flexibly controlled with the backpropagating photon being isolated. The transmission or isolated direction can be reversed via simply controlling the magnetic field direction applied to the magnons. The isolation bandwidth is improved by almost three times in comparison with the device based on a single PT-symmetric system. Moreover, the effect of intrinsic cavity loss and added thermal noises is considered, confirming the experimental feasibility of the nonreciprocal device and potential applications in quantum information processing.

Optomechanical squeezing with strong harmonic mechanical driving.

In this paper, we propose an optomechanical scheme for generating mechanical squeezing over the 3 dB limit, with the mechanical mirror being driven by a strong and linear harmonic force. In contrast to parametric mechanical driving, the linearly driven force shakes the mechanical mirror periodically oscillating at twice the mechanical eigenfrequency with large amplitude, where the mechanical mirror can be dissipatively stabilized by the engineered cavity reservoir to a dynamical squeezed steady state with a maximum degree of squeezing over 8 dB. The mechanical squeezing of more than 3 dB can be achieved even for a mechanical thermal temperature larger than 100 mK. The scheme can be implemented in a cascaded optomechanical setup, with potential applications in engineering continuous variable entanglement and quantum sensing.

One-pot synthesis of N-doped petroleum coke-based microporous carbon for high-performance CO2 adsorption and supercapacitors.

Waste resource utilization of petroleum coke is crucial for achieving global carbon emission reduction. Herein, a series of N-doped microporous carbons were fabricated from petroleum coke using a one-pot synthesis method. The as-prepared samples had a large specific surface area (up to 2512 m2/g), a moderate-high N content (up to 4.82 at.%), and high population (55%) of ultra-micropores (<0.7 nm). Regulating the N content and ultra-microporosity led to efficient CO2 adsorption and separation. At ambient pressure, the optimal N-doped petroleum coke-based microporous carbon exhibited the highest CO2 uptake of 4.25 mmol/g at 25°C and 6.57 mmol/g at 0°C. These values are comparable or even better than those of numerous previously reported adsorbents prepared by multistep synthesis, primarily due to the existence of ultra-micropores. The sample exhibited excellent CO2/N2 selectivity at 25°C owing to the abundant basic pyridinic and pyrrolic N species; and showed superior CO2 adsorption-desorption cycling performance, which was maintained at 97% after 10 cycles at 25°C. Moreover, petroleum coke-based microporous carbon, with a considerably high specific surface area and hierarchical pore structure, exhibited excellent electrochemical performance over the N-doped sample, maintaining a favorable specific capacitance of 233.25 F/g at 0.5 A/g in 6 mol/L KOH aqueous electrolyte. This study provides insight into the influence of N-doping on the porous properties of petroleum coke-based carbon. Furthermore, the as-prepared carbons were found to be promising adsorbents for CO2 adsorption, CO2/N2 separation and electrochemical application.

Precise preparation of biomass-based porous carbon with pore structure-dependent VOCs adsorption/desorption performance by bacterial pretreatment and its forming process.

Pore distribution characteristic is one of the most crucial factors for porous adsorption materials, and the variety of volatile organic compounds (VOCs) approaches about how to simply and accurately tailor practical porous carbons for VOCs adsorption has gradually attracted attention. Here, precursors with different lignocellulose mass ratios have been used to produce porous carbon for model experiments to investigate the influence of the precursor lignocellulose contents on the pore structure and distribution characteristics of porous carbon, and the applicability of these mechanisms to real biomass materials has been further verified through bacteria-targeted bagasse decomposition: the microvolumes of ultra-micropores have decreased with decrease in cellulose contents, while mesopores have followed the reverse trend. The dynamic toluene adsorption/desorption performances of the obtained samples have been tested. The BACs-36 exhibits high toluene adsorption performance in low concentration with 635 mg/g while the BACs-48 shows excellent reusability in 10 times cycles. Based on this the balance between the adsorptive and regenerative capacities has been observed which indicates that carbon materials with abundant micropores and narrow mesopores have much better adsorption performance than porous carbon with a hierarchical pore structure, while the latter show better regeneration abilities than the former, which resulting in less desorption as a counter-acting force at the pore wall. Furthermore, the porous carbon has been shaped by one-step co-pyrolysis method using phenolic resin, which can not only maintain the hardness but also can avoid pore plugging phenomenon.

Preparing hierarchical porous carbon with well-developed microporosity using alkali metal-catalyzed hydrothermal carbonization for VOCs adsorption.

Biomass-derived porous carbonaceous materials are efficient adsorbents for VOCs, but their traditional preparation method, pyrolysis combined with activation, suffers from high energy consumption, equipment corrosion, and low pore-making efficiency, which hinders their large-scale practical application. A novel method of alkali metal-catalyzed hydrothermal carbonization coupling with chemical activation for the preparation of microporous carbon is presented. Porous carbon with well-developed microporosity deriving from corn husk were prepared through the hydrothermal carbonization using potassium persulfate (K2S2O8) as a catalyst and programmed heating activation process. And the products were applied to removal of typical oxygen-containing VOCs, ethyl acetate. The addition of K2S2O8 in hydrothermal carbonization accelerated the biomass hydrolysis, decomposed the biopolymer, and formed functional hydrochars. Potassium salts introduced into the hydrochars, which acted as an activator in this programmed heating activation process, formed a great deal of micropores. The specific surface area of micropores increased by 81%, and the specific surface area of micropores less than 1 nm increased by 180%. The introduction of K2S2O8 in preparation improved the adsorption performance of CH-based porous carbons 16.46% and 60.00% respectively at different preparation temperatures (600 °C and 800 °C). Basing on these results, the improvement of micropores less than 1 nm is directly related to the adsorption performance. This indicates that pores (<1 nm) respond well to the adsorption of ethyl acetate.

Key factors and primary modification methods of activated carbon and their application in adsorption of carbon-based gases: A review.

To achieve carbon neutrality, it is necessary to control carbon-based gas emissions to the atmosphere. Among the various carbon-based gas removal technologies reported to date, adsorption is considered one of the most promising because of its economic efficiency, reusability, and low energy consumption. Activated carbon is widely used to treat different types of carbon-based gases owing to its large specific surface area, abundant functional groups, and strong adsorption capacity. This paper reviews the recent research progress into activated carbon as an adsorbent for carbon-based gases. The key factors (i.e., specific surface area, pore structure, and surface functional groups) affecting the adsorption of carbon-based gases by activated carbon were analyzed. The main methods employed to modify activated carbon (i.e., surface oxidation, surface reduction, loading materials, and plasma modification methods) to improve its adsorption capacity are also discussed herein, along with the targeted applications of such material in the adsorption of different types of carbon-based gases (such as aldehydes, ketones, aromatic hydrocarbons, halogenated hydrocarbons, and carbon-based greenhouse gases). Finally, the future development directions and challenges of activated carbon are discussed. Our work will be expected to benefit the development of activated carbon exhibiting selective adsorption properties, and reduce the production costs of adsorbents.

Preparation of porous carbon based on partially degraded raw biomass by Trichoderma viride to optimize its toluene adsorption performance.

Volatile organic compounds (VOCs), which are usually organic compounds with boiling point in the range of 50 to 260°C, pose a serious threat to human health and ecological environment. In order to find an adsorbent with excellent adsorption effect on VOCs, activated carbon was prepared from corn bran partially degraded by Trichoderma viride, and the adsorption performance of the optimized porous carbon materials on toluene was studied. Physical and chemical properties (such as specific surface area, pore size distribution, and surface functional groups) of the activated carbon were characterized by scanning electron microscope (SEM), N2 adsorption/desorption experiences, Fourier-transform infrared (FTIR), and Raman and X-ray diffraction (XRD). The results showed that the specific surface area of corn bran reached 1896 m2/g and the total pore volume was 1.04 cm3/g after 15 days of microbial pretreatment. Dynamic simulation of adsorption experiment found that the saturated adsorption capacity of the pretreated carbon material was 237 mg/g at 100 ppm toluene concentration, which was 1.58 times of that of corn bran without microbial pretreatment. Generally, the improvement of adsorption performance may be mainly attributed to the increase of specific surface area, pore volume and the decrease of surface acidic groups.

Hierarchical porous carbon fabricated from cellulose-degrading fungus modified rice husks: Ultrahigh surface area and impressive improvement in toluene adsorption.

The porous carbon materials formed from biomass precursors are promising candidates for adsorbing organic vapor pollutants. However, these materials have insufficient pores, which hinder their accessibility to adsorbates. This study develops an ultrahigh-surface-area porous carbon adsorbent with interlacing micro-mesoporous structures through Trichoderma viride decomposition. An orthogonal experiment is conducted, and the most suitable conditions for fabricating porous carbon with an ultrahigh SBET of 3714 m2.g-1 and a hierarchical porous structure are identified. This work achieves one of the highest specific surface areas of biomass carbons among recent studies. T. viride corrodes the internal and external microstructures of rice husks, and regulates the lignin, cellulose, and hemicellulose contents, which improve the efficiency of carbonization and chemical activation. The carbonaceous materials with microbial pretreatment exhibit better toluene adsorption performances (100 ppm: 708 mg.g-1), adsorption rates, and cyclic utilization than those without pretreatment (100 pm: 538 mg.g-1). In addition, grand canonical Monte Carlo simulation is conducted. The micropores and mesopores created after microbial pretreatment are effective toluene adsorption sites. Moreover, the diffusion coefficient calculated by utilizing Thomas model and Chemical diffusion verify that the mesopores accelerate the kinetic process of toluene adsorption.