RESUMO
The electrocatalytic nitrogen reduction reaction (NRR) is a promising technology for the synthesis of NH3 in an ambient environment. However, developing low-cost and high-efficiency electrocatalysts still remains a long-standing challenge. In this work, density function theory (DFT) calculations are done to systematically investigate the NRR catalytic activity of transition metals (TM = Sc-Cu, Y-Ag, and Hf-Au) supported on monolayer graphyne (GY). TM@GY (TM = Sc, V, Mn, Y, Tc, and Os) with excellent NRR performance are demonstrated. The mixed pathway is the most favorable for Sc, V, Y, and Os@GY with the potentials of -0.37, -0.27, -0.40, and -0.36 V, respectively, while the distal reaction pathway is most favorable for Mn and Tc@GY with the potentials of -0.37 and -0.42 V. Most strikingly, Mn, Tc, and Os@GY exhibit high NRR selectivity. This work provides a screening scheme for exploring highly efficient electrocatalysts for the electrochemical NRR under ambient conditions.
RESUMO
Based on the Monte Carlo (MC) method, a non-coplanar ultraviolet (UV) multiple-scatter propagation model with a height difference between the transmitter (Tx) and receiver (Rx) was presented. We focused on the relationship between bit error rate (BER) and the height difference between the Tx and Rx. We also studied the impact of the elevation angle and the off-axis angle of the Tx and Rx on the BER under the condition that the height difference is not zero. In addition, an outdoor UV communication testbed was set up to provide support for the validity of the MC model. The simulation results show that when the height difference between the Tx and Rx increases, the BER first decreases and then increases, the BER can be reduced by adjusting the transceiver elevation angle, and the bigger the off-axis angle is, the bigger BER is. The experimental results are in good agreement with the simulation results.
