Performance of Water Oxidation by 3D Printed Electrodes Modified by Prussian Blue Analogues

The water oxidation is the limiting step in the water-splitting process. Given this scenario, the development of new catalysts is essential in this field. The emergent demand is the use of Earth-abundant elements and catalysts with high performance under mild conditions. Because of this, catalysts such as Prussian Blue analogues (PBA) have been receiving a lot of attention in recent years. In addition, working under neutral conditions allows us to take advantage of the modification of conductive polymeric 3D printed electrodes (3DPE) with Prussian Blue. Thus, we described in this work the development of the polymeric 3D printed electrodes modified by cobalt-Prussian Blue and their performance in the water oxidation process. The 3D printed electrodes modified with Co3[Co(CN)6]2 (Co-Co PBA) have a Tafel slope of 343 mV dec−1 while those modified with Co3[Fe(CN)6]2 (Co-Fe PBA) have a Tafel slope of 378 mV dec−1. This means that both catalysts have the same mechanism for the water oxidation process. On the other hand, the overpotential of Co-Co PBA in 3DPE is lower than the value observed by Co-Fe PBA in 3DPE suggesting the best electrocatalytic activity for Co-Co PBA catalyst.

水氧化反应是水分解过程中的限速步骤。在此背景下，开发新型催化剂是该领域的核心要务。当前的新兴需求是采用地壳富存元素制备催化剂，且该类催化剂需在温和条件下展现优异性能。正因如此，普鲁士蓝类似物（Prussian Blue Analogues, PBA）近年来受到了广泛关注。此外，在中性条件下开展实验，可借助普鲁士蓝对导电聚合物基3D打印电极（conductive polymeric 3D printed electrodes, 3DPE）进行改性。因此，本工作报道了钴基普鲁士蓝改性的3D打印电极的制备及其在水氧化反应中的催化性能。经Co₃[Co(CN)₆]₂（Co-Co PBA）改性的3DPE的塔菲尔斜率为343 mV·dec⁻¹，而经Co₃[Fe(CN)₆]₂（Co-Fe PBA）改性的3DPE的塔菲尔斜率为378 mV·dec⁻¹。这表明两种催化剂在水氧化过程中遵循相同的反应机制。另一方面，Co-Co PBA改性3DPE的过电位低于Co-Fe PBA改性3DPE的过电位，说明Co-Co PBA催化剂具备更优异的电催化活性。