CoCu双金属电极近中性高效电催化硝酸盐产氨

Efficient electrocatalytic nitrate-to-ammonia conversion on CoCu bimetallic electrodes under near-neutral conditions

  • 摘要: 通过电化学还原硝酸盐将其高选择性转化为氨可视为一种高效的硝酸盐资源化去除技术。通过电沉积结合原位退火制备了CoCu双金属电极。系统研究了沉积液金属比例、施加电位及初始pH值对催化剂性能的影响。结果表明,在近中性环境(pH = 6)、电位为−0.60 V vs RHE且沉积液中Cu∶Co比例为5∶5时,催化剂表现出最优性能,其 \textNO_\text3^-\text-N 的去除率高达97.80%, \textN\textH_\text3\text-N 产率高达2824.85 μg·h−1·cm−2,法拉第效率达93.22%, \textN\textH_\text3\text-N 选择性为97.10%。捕获剂实验证实反应过程中水解产生的活性氢(*H)是关键中间体。机制研究表明,Co与Cu位点协同催化:Cu位点优先吸附并快速转化 \textNO_\text3^-\text-N 为 \textNO_\text2^-\text-N 中间体,Co位点则有效促进 \textNO_\text2^-\text-N 的脱氧加氢生成 \textN\textH_\text3\text-N 。密度泛函理论计算表明,Co的掺杂显著降低了产生*H的能垒。上述协同效应显著提升了催化剂的活性与选择性,为硝酸盐污染治理提供了思路参考。

     

    Abstract: The electrocatalytic reduction of nitrate for its highly selective conversion to ammonia can be regarded as an efficient nitrate removal and resource recovery technology. CoCu bimetal electrodes were fabricated via electrodeposition combined with in-situ annealing. The effects of the metal ratio in the deposition solution, applied potential, and initial pH on the catalyst performance were systematically investigated. The results demonstrate that under near-neutral conditions (pH = 6), at an applied potential of −0.60 V vs RHE and a Cu∶Co ratio of 5∶5 in the deposition solution, the catalyst exhibited optimal performance. This included a \textNO_\text3^-\text-N removal rate of 97.80%, an \textN\textH_\text3\text-N yield rate of 2824.85 μg·h−1·cm−2, a Faradaic efficiency of 93. 22%, and an \textN\textH_\text3\text-N selectivity of 97.10%. Scavenger experiments confirmed that the active hydrogen atoms (*H) generated via hydrolysis during the reaction are key intermediates. Mechanism studies reveal that Co and Cu sites synergistically catalyze the reaction: Cu sites preferentially adsorb and rapidly convert \textNO_\text3^-\text-N into the intermediate \textNO_\text2^-\text-N , while Co sites effectively promote the deoxygenation and hydrogenation of \textNO_\text2^-\text-N to generate \textN\textH_\text3\text-N . Density functional theory calculations indicate that Co doping significantly reduces the energy barrier for *H generation. This synergistic effect markedly enhances the activity and selectivity of the catalyst, providing valuable insights for nitrate pollution control.

     

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