A Simple equivalent circuit model is developed for a wireless energy transfer system via coupled magnetic resonances and a practical design method is also provided. Node equations for the resonance system are built with the method, expanding on the equations for a transformer, and the optimum distances of coils in the system are derived analytically for optimum coupling coefficients for high transfer efficiency. In order to calculate the frequency characteristics for a lossy system, the equivalent model is established at an electric design automation tool. The model parameters of the actual system are extracted and the modeling results are compared with measurements. Through the developed model, it is seen that the system can transfer power over a mid-range of a few meters and impedance matching is important to achieve high efficiency. This developed model can be used for a design and prediction on the similar systems such as increasing the number of receiving coils and receiving modules, etc.

The electrochemical conversion of nitric oxide (NO) to ammonia (NH3) provides a sustainable route to transform an air pollutant into a value-added chemical. However, the development of NO electroreduction remains hindered by the poor solubility in aqueous electrolytes, requiring the use of concentrated NO. Here, we report a dilute NO reduction using a gas diffusion electrode (GDE) to circumvent the mass transport issue. Through the incorporation of nanoscale zero-valent iron into carbon black on the GDE, 96% NH3 Faradaic efficiency was achieved with 1% NO, and the computational calculations revealed that the Fe catalyzed the breaking of the N–O bond in the H2NO intermediate. The NH3 production rate was accelerated by controlling the concentration of protons in the electrolyte and reached 1239 μmol cm–2 h–1 with 10% NO. Our findings show that the gas-phase electrolysis of dilute NO can offer a practical option for upcycling the waste nitrogen.

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A general equivalent circuit model is developed for a wireless energy transfer system composed of multiple coils via coupled magnetic resonances. To verify the developed model, four types of wireless energy transfer systems are fabricated, measured, and compared with simulation results. To model a system composed of n‐coils, node equations are built in the form of an n‐by‐n matrix, and the equivalent circuit model is established using an electric design automation tool. Using the model, we can simulate systems with multiple coils, power sources, and loads. Moreover, coupling constants are extracted as a function of the distance between two coils, and we can predict the characteristics of a system having coils at an arbitrary location. We fabricate four types of systems with relay coils, two operating frequencies, two power sources, and the function of characteristic impedance conversion. We measure the characteristics of all systems and compare them with the simulation results. The flexibility of the developed model enables us to design and optimize a complicated system consisting of many coils.