Intrinsic Catalytic Activity of Carbon Nanotubes for Electrochemical Nitrate Reduction
Intrinsic Catalytic Activity of Carbon Nanotubes for Electrochemical Nitrate Reduction
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DOI：
10.1021/acscatal.2c01144
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发表时间：
2022-08-05
期刊：
影响因子：
12.9
通讯作者：
Wang, Hailiang
中科院分区：
文献类型：
--
作者：
Harmon, Nia J.;Rooney, Conor L.;Wang, Hailiang
我们研究了各种碳纳米管（CNT）作为具有成本效益的催化剂的电化学硝酸盐（NO3-）还原反应，这有望将环境NO3-污染物转化为有用的氨（NH3）产品。我们发现，原始的多壁碳纳米管（MWCNTs）表现出显着的电催化活性，NO3-还原为NH3在近中性电解质。单壁碳纳米管对该反应具有比MWCNTs更高的活性和选择性。对照实验的结果证实，这种活性源自天然碳表面，而不是金属杂质。与杂原子掺杂到碳材料中杂质的流行观念相反。相反，普遍的掺杂提高了它们的电催化性能，我们发现，引入氧和氮功能基团的多壁碳纳米管降低其电催化还原NO3-的活性。在分析了CNT催化剂的电位依赖性电催化性能后，我们进一步报告了总电流密度和法拉第效率之间的有趣的正相关性，无论CNT的类型如何。这种相关性表明更深的NO3-还原在较高的反应速率，无论催化剂的身份。这项工作中提出的研究结果表明，一种独特的类型的活性位点的电催化NO3-还原，因此扩大了碳材料在电催化中的作用。
We study a variety of carbon nanotubes (CNTs) as cost-effective catalysts for the electrochemical nitrate (NO3-) reduction reaction, which holds promise for converting environmental NO3- pollutants into useful ammonia (NH3) products. We discover that pristine multi-walled carbon nanotubes (MWCNTs) exhibit notable electrocatalytic activity for NO3- reduction to NH3 in a near-neutral electrolyte. Single-walled carbon nanotubes have even higher activity and selectivity than MWCNTs for this reaction. Results from control experiments confirm that this activity originates from the native carbon surface rather than from metal impurities. Contrary to the prevalent notion that heteroatom doping into carbon materials impurities. Contrary prevalent doping increases their electrocatalytic performance, we find that introducing oxygen and nitrogen functional groups into MWCNTs reduces their electrocatalytic activity for NO3- reduction. After analyzing the potential-dependent electrocatalytic performance of the CNT catalysts, we further report an interesting positive correlation between total current density and Faradaic efficiency for NH3 formation irrespective of the type of CNT. This correlation suggests deeper NO3- reduction at higher reaction rates regardless of the catalyst identity. The findings presented in this work suggest a unique type of active site for electrocatalytic NO3- reduction, therefore broadening the role of carbon materials in electrocatalysis.