Nitrite contamination in agricultural and industrial wastewater presents a critical impact on environmental sustainability, demanding efficient strategies for monitoring and remediation. This study addresses this challenge by developing cost-effective electrocatalysts for both nitrite detection and conversion to value-added ammonia. 3D printed carbon materials are explored as bifunctional platforms for the electrochemical nitrite oxidation reaction (NO₂OR) and nitrite reduction reaction (NO₂RR). Benefiting from the inherent Ti-dominated metallic impurities and intrinsic surface features of carbon nanotubes, 3D printed carbon electrodes exhibit electrocatalytic activity for both reactions. To enhance this activity, we further introduce an effective fabrication methodology that combines 3D printing of carbon substrates with precise surface modification using atomic layer deposition (ALD) of TiO₂. The resulting TiO₂-coated carbon electrode demonstrates significantly improved electrocatalytic properties. For NO₂OR, it exhibits a peak current density of 0.75 mA cm⁻² at 1.53 V vs. RHE, while for NO₂RR, it achieves a yield rate of 630.5 µg h⁻¹ cm⁻² with a faradaic efficiency of 81.9% at −1.06 V vs. RHE. This enhancement in electrocatalytic activity is primarily attributed to the formation of abundant interfaces between the conductive carbon and ALD-coated TiO₂. The developed methodology not only enables precise modification of 3D printed carbon surface chemistry but also presents a scalable method for electrocatalyst production.

中文翻译：

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用于电催化亚硝酸盐氧化和还原为氨的 3D 打印碳表面化学的原子调谐


农业和工业废水中的亚硝酸盐污染对环境可持续性产生重大影响，需要有效的监测和补救策略。本研究通过开发用于亚硝酸盐检测和转化为增值氨的经济有效的电催化剂来应对这一挑战。3D 打印碳材料被探索为电化学亚硝酸盐氧化反应 （NO₂OR） 和亚硝酸盐还原反应 （NO₂RR） 的双功能平台。得益于碳纳米管固有的 Ti 主导金属杂质和固有的表面特性，3D 打印碳电极在这两个反应中都表现出电催化活性。为了加强这项活动，我们进一步引入了一种有效的制造方法，该方法将碳基材的 3D 打印与使用 TiO₂ 原子层沉积 （ALD） 的精确表面改性相结合。所得的 TiO₂ 涂层碳电极表现出显著改善的电催化性能。对于 NO₂OR，它在 1.53 V vs. RHE 下表现出 0.75 mA ^cm-2 的峰值电流密度，而对于 NO₂RR，它在 -1.06 V vs. RHE 下达到 630.5 μg ^{h-1 cm-2} 的产率和 81.9% 的法拉第效率。电催化活性的增强主要归因于导电碳和 ALD 涂层的 TiO₂ 之间形成丰富的界面。 开发的方法不仅可以精确修饰 3D 打印碳表面化学，而且还提供了一种可扩展的电催化剂生产方法。