Embedding Double Transition Metal Atoms in B-Modified Two-Dimensional Carbon-Rich Conjugated Frameworks for Efficient Ammonia Synthesis.

It is important to develop an efficient green catalyst for electrochemical nitrogen reduction under environmental conditions to replace the Haber-Bosch process with high energy consumption, limited economic scale of production, and high CO2 emissions, but there are still some difficulties in its development and design. In this work, based on 2D CCFs, a B-modified rectangular-shaped expanded phthalocyanine bimetallic atomic catalyst is proposed. Because both the TM-d orbital and the B-sp3 hybrid orbital can accept the lone pair and feedback electrons of N2, and there are significantly different valence electron distributions between the two different metals and boron, this catalyst not only keep the advantages of metal catalysts but also play the role of the B atom to further increase the polarity of nitrogen and activate N2. In order to evaluate the catalytic performance of this catalyst, its stability, activity, selectivity, reactivity, and other aspects are screened and analyzed by density functional theory calculation. Among them, the FeNb-BPc CCF catalyst has better N2 adsorption capacity under ambient conditions, exhibits excellent catalytic activity through a continuous mechanism, and has a lower limiting potential of -0.24 V. We believe that this work opens a new path for the rational design of efficient N2 reduction reaction catalysts and also provides a theoretical basis for experimental development.

Dual-Band Dual-Mode Substrate Integrated Waveguide Filters with Independently Reconfigurable TE101 Resonant Mode.

A novel perturbation approach using additional metalized via-holes for implementation of the dual-band or wide-band dual-mode substrate integrated waveguide (SIW) filters is proposed in this paper. The independent perturbation on the first resonant mode TE101 can be constructed by applying the proposed perturbation approach, whereas the second resonant mode TE102 is not affected. Thus, new kinds of dual-band or wide-band dual-mode SIW filters with a fixed or an independently reconfigurable low-frequency band have been directly achieved. In order to experimentally verify the proposed design method, four two-cavity dual-band SIW filters, which have different numbers of perturbation via-holes in each cavity, and a two-cavity dual-band SIW filter, which includes four via-holes and eight reconfigurable states in each cavity, are designed and experimentally assessed. The measured results indicate that the available frequency-ratio range from 1 to 1.3 can be realized by using four two-cavity dual-band SIW filters. The center frequency of the first band can be tuned from 4.61 GHz to 5.24 GHz, whereas the center frequency of the second one is fixed at around 6.18 GHz for the two-cavity dual-band SIW filter with four reconfigurable states via-holes. All the simulated and measured results show an acceptable agreement with the predicted data.