Marrocchi Assunta, Cerza Elisa, Chandrasekaran Suhas, Sgreccia Emanuela, Kaciulis Saulius, Vaccaro Luigi, Syahputra Suanto, Vacandio Florence, Knauth Philippe, Di Vona Maria Luisa
Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy.
Tor Vergata University of Rome, Department Industrial Engineering and International Laboratory: Ionomer Materials for Energy (LIME), 00133 Roma, Italy.
Molecules. 2024 Jul 11;29(14):3286. doi: 10.3390/molecules29143286.
Hydrothermal carbonization (HTC) serves as a sustainable method to transform pine needle waste into nitrogen-doped (N-doped) hydrochars. The primary focus is on evaluating these hydrochars as catalytic electrodes for the oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CORR), which are pivotal processes with significant environmental implications. Hydrochars were synthesized by varying the parameters such as nitrogen loading, temperature, and residence time. These materials were then thoroughly characterized using diverse analytical techniques, including elemental analysis, density measurements, BET surface area analysis, and spectroscopies like Raman, FTIR, and XPS, along with optical and scanning electron microscopies. The subsequent electrochemical assessment involved preparing electrocatalytic inks by combining hydrochars with an anion exchange ionomer (AEI) to leverage their synergistic effects. To the best of our knowledge, there are no previous reports on catalytic electrodes that simultaneously incorporate both a hydrochar and AEI. Evaluation metrics such as current densities, onset and half-wave potentials, and Koutecky-Levich and Tafel plots provided insights into their electrocatalytic performances. Notably, hydrochars synthesized at 230 °C exhibited an onset potential of 0.92 V vs. RHE, marking the highest reported value for a hydrochar. They also facilitated the exchange of four electrons at 0.26 V vs. RHE in the ORR. Additionally, the CORR yielded valuable C products like acetaldehyde and acetate. These findings highlight the remarkable electrocatalytic activity of the optimized hydrochars, which could be attributed, at least in part, to their optimal porosity.
水热碳化（HTC）是一种将松针废料转化为氮掺杂（N掺杂）水焦的可持续方法。主要重点是评估这些水焦作为氧还原反应（ORR）和二氧化碳还原反应（CORR）的催化电极，这两个关键过程具有重大的环境意义。通过改变氮负载量、温度和停留时间等参数合成水焦。然后使用多种分析技术对这些材料进行全面表征，包括元素分析、密度测量、BET表面积分析以及拉曼光谱、傅里叶变换红外光谱（FTIR）和X射线光电子能谱（XPS）等光谱技术，以及光学显微镜和扫描电子显微镜。随后的电化学评估包括将水焦与阴离子交换离聚物（AEI）混合制备电催化墨水，以利用它们的协同效应。据我们所知，此前没有关于同时包含水焦和AEI的催化电极的报道。电流密度、起始和半波电位以及科捷茨基-列维奇（Koutecky-Levich）和塔菲尔（Tafel）图等评估指标提供了对其电催化性能的见解。值得注意的是，在230°C下合成的水焦相对于可逆氢电极（RHE）的起始电位为0.92 V，这是报道的水焦的最高值。它们还在相对于RHE为0.26 V时促进了ORR中的四电子交换。此外，CORR产生了乙醛和乙酸盐等有价值的C产物。这些发现突出了优化后的水焦卓越的电催化活性，这至少部分可归因于它们的最佳孔隙率。
