一种新型太阳能热电化学耦合甲烷重整制氢脱碳与太阳能储能方法

Hydrogen is widely regarded as a sustainable energy carrier with tremendous potential for low-carbon energy transition.Solar photovoltaic-driven water electrolysis(PV-E)is a clean and sustainable approach of hydrogen production,but with major barriers of high hydrogen production costs and limited capacity.Steam methane reforming(SMR),the state-of-the-art means of hydrogen production,has yet to overcome key obstacles of high reaction temperature and CO_(2)emission for sustainability.This work proposes a solar thermo-electrochemical SMR approach,in which solar-driven mid/low-temperature SMR is combined with electrochemical H_(2)separation and in-situ CO_(2)capture.The feasibility of this method is verified experimentally,achieving an average methane conversion of 96.8%at a dramatically reduced reforming temperature of 400-500℃.The underlying mechanisms of this method are revealed by an experimentally calibrated model,which is further employed to predict its performance for thermoelectrochemical hydrogen production.Simulation results show that a net solar-to-H_(2)efficiency of26.25%could be obtained at 500℃,which is over 11 percentage points higher than that of PV-E;the first-law thermodynamic efficiency reaches up to 63.27%correspondingly.The enhanced efficiency also leads to decreased fuel consumption and lower CO_(2)emission of the proposed solar-driven SMR system.Such complementary conversion of solar PV electricity,solar thermal energy,and low-carbon fuel provides a synergistic and efficient means of sustainable H_(2)production with potentially long-term solar energy storage on a vast scale.

High sulfur loading and shuttle inhibition of advanced sulfur cathode enabled by graphene network skin and N,P,F-doped mesoporous carbon interfaces for ultra-stable lithium sulfur battery

Achieving high loading of active sulfur yet rational regulating the shuttle effect of lithium polysulfide(LiPS)is of great significance in pursuit of high-performance lithium-sulfur(Li-S)battery.Herein,we develop a free-standing graphene nitrogen(N),phosphorus(P)and fluorine(F)co-doped mesoporous carbon-sulfur(G-NPFMC-S)film,which was used as a binder-free cathode in Li-S battery.The developed mesoporous carbon(MC)achieved a high specific surface area of 921 m^(2)·g^(-1)with a uniform pore size distribution of 15 nm.The inserted graphene network inside G-NPFMC-S cathode can effectively improve its electrical conductivity and simultaneously restrict the shuttle of LiPS.A high sulfur loading of 86%was achieved due to the excellent porous structures of graphene-NPFMC(G-NPFMC)composite.When implemented as a freestanding cathode in Li-S battery,this G-NPFMC-S achieved a high specific capacity(1,356 mAh·g^(-1)),favorable rate capability,and long-term cycling stability up to 500 cycles with a minimum capacity fading rate of 0.025%per cycle,outperforming the corresponding performances of NPFMC-sulfur(NPFMC-S)and MC-sulfur(MC-S).These promising results can be ascribed to the featured structures that formed inside G-NPFMC-S film,as that highly porous NPFMC can provide sufficient storage space for the loading of sulfur,while,the N,P,F-doped carbonic interface and the inserted graphene network help hinder the shuttle of LiPS via chemical adsorption and physical barrier effect.This proposed unique structure can provide a bright prospect in that high mass loading of active sulfur and restriction the shuttle of LiPS can be simultaneously achieved for Li-S battery.

A hybrid carbon aerogel with both aligned and interconnected pores as interlayer for high-performance lithium-sulfur batteries

The soluble nature of polysulfide species created on the sulfur electrode has severely hampered the electrochemical performance of lithium-sulfur （Li-S） batteries. Trapping and anchoring polysulfides are promising approaches for overcoming this issue. In this work, a mechanically robust, electrically conductive hybrid carbon aerogel （HCA） with aligned and interconnected pores was created and investigated as an interlayer for Li-S batteries. The hierarchical cross-linked networks constructed by graphene sheets and carbon nanotubes can act as an ＂internet＂ to capture the polysulfide, while the micro- and nano-pores inside the aerogel can facilitate quick penetration of the electrolyte and rapid transport of lithium ions. As advantages of the unique structure and excellent accommodation of the volume change of the active materials, a high specific capacity of 1,309 mAh.g-1 at 0.2 C was achieved for the assembled Li-S battery, coupled with good rate performance and long-term cycling stability （78% capacity retention after 600 cycles at 4 C）.

Ultrathin tunable terahertz absorber based on MEMS-driven metamaterial

The realization of high-performance tunable absorbers for terahertz frequencies is crucial for advancing applications such as single-pixel imaging and spectroscopy.Based on the strong position sensitivity of metamaterials’electromagnetic response,we combine meta-atoms that support strongly localized modes with suspended flat membranes that can be driven electrostatically.This design maximizes the tunability range for small mechanical displacements of the membranes.We employ a micro-electromechanical system technology and successfully fabricate the devices.Our prototype devices are among the best-performing tunable THz absorbers demonstrated to date,with an ultrathin device thickness(~1/50 of the working wavelength),absorption varying between 60%and 80%in the initial state when the membranes remain suspended,and fast switching speed(~27μs).The absorption is tuned by an applied voltage,with the most marked results achieved when the structure reaches the snap-down state.In this case,the resonance shifts by >200% of the linewidth(14% of the initial resonance frequency),and the absolute absorption modulation measured at the initial resonance can reach 65%.The demonstrated approach can be further optimized and extended to benefit numerous applications in THz technology.

Topology-empowered membrane devices for terahertz photonics

Control of terahertz waves offers a profound platform for next-generation sensing,imaging,and information communications.However,all conventional terahertz components and systems suffer from bulky design,sensitivity to imperfections,and transmission loss.We propose and experimentally demonstrate onchip integration and miniaturization of topological devices,which may address many existing drawbacks of the terahertz technology.We design and fabricate topological devices based on valley-Hall photonic structures that can be employed for various integrated components of on-chip terahertz systems.We demonstrate valleylocked asymmetric energy flow and mode conversion with topological waveguide,multiport couplers,wave division,and whispering gallery mode resonators.Our devices are based on topological membrane metasurfaces,which are of great importance for developing on-chip photonics and bring many features into terahertz technology.