Cuatto Giulia, De Meis Elenia, Guzmán Hilmar, Hernández Simelys
CREST Group, Department of Applied Science and Technology (DISAT), Politecnico di Torino, C.so Duca degli Abruzzi, 24, 10129 Turin, Italy.
Clean Water Center (CWC), Politecnico di Torino, C.so Duca degli Abruzzi, 24, 10129 Turin, Italy.
Nanomaterials (Basel). 2025 Sep 18;15(18):1434. doi: 10.3390/nano15181434.
Currently, the growing demand for sustainable hydrogen makes the oxygen evolution reaction (OER) increasingly important. To boost the performance of electrochemical cells for water electrolysis, both cathodic and anodic sides need to be optimized. Noble metal catalysts for the OER suffer from high costs and limited availability; therefore, developing efficient, low-cost alternatives is crucial. This work investigates manganese-based materials as potential noble-metal-free catalysts. Mn antimonates, Mn chlorates, and Mn bromates were synthesized using ultrasound-assisted techniques to enhance phase composition and homogeneity. Physicochemical characterizations were performed using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), together with energy-dispersive X-ray spectroscopy (EDX) and surface area analyses. All samples exhibited a low surface area and inter-particle porosity within mixed crystalline phases. Among the catalysts, MnOBr, synthesized via ultrasound homogenization (30 min at 59 kHz) and calcined at 250 °C, showed the highest OER activity. Drop-casted on Fluorine-Doped Tin Oxide (FTO)-coated Ti mesh, it achieved an overpotential of 153 mV at 10 mA cm, with Tafel slopes of 103 mV dec and 160 mV dec at 1, 2, and 4 mA cm and 6, 8, 10, and 11 mA cm, respectively. It also demonstrated good short-term stability (1 h) in acidic media, with a strong signal-to-noise ratio. Its short-term stability is comparable to that of the benchmark IrO, with a potential drift of 15 mV h and a standard deviation of 3 mV for the best-performing electrode. The presence of multiple phases suggests room for further optimization. Overall, this study provides a practical route for designing noble metal-free Mn-based OER catalysts.
目前，对可持续氢气不断增长的需求使得析氧反应（OER）变得越来越重要。为了提高水电解电化学电池的性能，阴极和阳极都需要进行优化。用于OER的贵金属催化剂成本高昂且供应有限；因此，开发高效、低成本的替代品至关重要。这项工作研究了锰基材料作为潜在的无贵金属催化剂。使用超声辅助技术合成了锰锑酸盐、锰氯酸盐和锰溴酸盐，以提高相组成和均匀性。使用X射线衍射（XRD）、扫描电子显微镜（SEM）以及能量色散X射线光谱（EDX）和表面积分析进行了物理化学表征。所有样品在混合晶相内均表现出低表面积和颗粒间孔隙率。在这些催化剂中，通过超声均质化（59 kHz下30分钟）合成并在250°C下煅烧的MnOBr表现出最高的OER活性。滴铸在氟掺杂氧化锡（FTO）涂层的钛网上，在10 mA cm时过电位为153 mV，在1、2和4 mA cm以及6、8、10和11 mA cm时的塔菲尔斜率分别为103 mV dec和160 mV dec。它在酸性介质中还表现出良好的短期稳定性（1小时），信噪比高。其短期稳定性与基准IrO相当，性能最佳的电极的电位漂移为15 mV h，标准偏差为3 mV。多相的存在表明有进一步优化的空间。总体而言，这项研究为设计无贵金属的锰基OER催化剂提供了一条实用途径。
