Abstract：
The electrochemical nitrogen reduction reaction (eNRR) is a highly promising alternative to the Haber-Bosch (H-B) process, but its commercial development is limited by the high bond energy of N2 molecules and the presence of the competitive hydrogen evolution reaction (HER). Here, a metal-free composite electrocatalyst of boron nitride (h-BNNs) and carbon nanotubes (CNTs) was explored through the interfacial hybridization of h-BNNs and CNTs, which showed a highly improved eNRR Faraday efficiency (FE) of 63.9% and an NH3 yield rate of 36.5 μg h-1 mgcat.-1 at -0.691 V (vs RHE). New chemical bonds of C-B and C-N were observed, indicating a strong interaction between CNTs and h-BNNs. According to the Raman spectra and the optimized model of h-BNNs/CNTs, an obvious strain effect between h-BNNs and CNTs was supposed to play a significant role in the highly improved FE, compared with the FE of h-BNNs alone (4.7%). Density functional theory (DFT) calculations further showed that h-BNNs/CNTs had lower energy barriers in eNRR, giving them higher N2 to NH3 selectivity, while h-BNNs have lower energy barriers in the HER. This work shows the important role of the strain effect in boosting the selectivity in the eNRR process.
摘要：
电化学氮还原反应（eNRR）是Haber-Bosch（H-B）工艺的极有希望的替代方法，但其商业发展受到N2分子的高键能和竞争性析氢反应(HER)的存在的限制。这里,通过h-BNN和CNT的界面杂化，探索了氮化硼（h-BNN）和碳纳米管（CNT）的无金属复合电催化剂，显示出大大提高的eNRR法拉第效率（FE）为63.9％，NH3产率为36.5μgh-1mgcat。-0.691V时为-1（与RHE相比）。观察到新的C-B和C-N化学键,表明碳纳米管和h-BNN之间存在强烈的相互作用。根据拉曼光谱和优化的h-BNN/CNT模型,h-BNN和CNT之间明显的应变效应被认为在高度改进的FE中起着重要作用，与单独的h-BNN的FE（4.7%）相比。密度泛函理论（DFT）计算进一步表明，h-BNN/CNT在eNRR中具有较低的能量势垒，给他们更高的N2对NH3的选择性，而h-BNN在她体内具有较低的能量壁垒。这项工作显示了菌株效应在增强eNRR过程中的选择性方面的重要作用。
