Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK.
Nanoscale. 2016 Aug 21;8(31):14767-77. doi: 10.1039/c6nr04073j. Epub 2016 Jul 22.
Two-dimensional molybdenum disulphide nanosheets (2D-MoS2) have proven to be an effective electrocatalyst, with particular attention being focused on their use towards increasing the efficiency of the reactions associated with hydrogen fuel cells. Whilst the majority of research has focused on the Hydrogen Evolution Reaction (HER), herein we explore the use of 2D-MoS2 as a potential electrocatalyst for the much less researched Oxygen Reduction Reaction (ORR). We stray from literature conventions and perform experiments in 0.1 M H2SO4 acidic electrolyte for the first time, evaluating the electrochemical performance of the ORR with 2D-MoS2 electrically wired/immobilised upon several carbon based electrodes (namely; Boron Doped Diamond (BDD), Edge Plane Pyrolytic Graphite (EPPG), Glassy Carbon (GC) and Screen-Printed Electrodes (SPE)) whilst exploring a range of 2D-MoS2 coverages/masses. Consequently, the findings of this study are highly applicable to real world fuel cell applications. We show that significant improvements in ORR activity can be achieved through the careful selection of the underlying/supporting carbon materials that electrically wire the 2D-MoS2 and utilisation of an optimal mass of 2D-MoS2. The ORR onset is observed to be reduced to ca. +0.10 V for EPPG, GC and SPEs at 2D-MoS2 (1524 ng cm(-2) modification), which is far closer to Pt at +0.46 V compared to bare/unmodified EPPG, GC and SPE counterparts. This report is the first to demonstrate such beneficial electrochemical responses in acidic conditions using a 2D-MoS2 based electrocatalyst material on a carbon-based substrate (SPEs in this case). Investigation of the beneficial reaction mechanism reveals the ORR to occur via a 4 electron process in specific conditions; elsewhere a 2 electron process is observed. This work offers valuable insights for those wishing to design, fabricate and/or electrochemically test 2D-nanosheet materials towards the ORR.
二维二硫化钼纳米片（2D-MoS2）已被证明是一种有效的电催化剂，特别关注其在提高与氢燃料电池相关反应效率方面的应用。虽然大多数研究都集中在析氢反应（HER）上，但本文探索了 2D-MoS2 作为一种潜在电催化剂在氧还原反应（ORR）中的应用，该反应的研究较少。我们偏离文献惯例，首次在 0.1 M H2SO4 酸性电解质中进行实验，评估了 2D-MoS2 在几种碳基电极（即掺硼金刚石（BDD）、边缘平面热解石墨（EPPG）、玻璃碳（GC）和丝网印刷电极（SPE））上电连接/固定的 ORR 电化学性能，同时探索了一系列 2D-MoS2 覆盖率/质量。因此，本研究的结果非常适用于实际的燃料电池应用。我们表明，通过仔细选择电连接 2D-MoS2 的基础/支撑碳材料以及使用最佳质量的 2D-MoS2，可以显著提高 ORR 活性。对于 EPPG、GC 和 SPE，在 2D-MoS2（1524 ng cm(-2)修饰）存在下，ORR 的起始电位观察到降低到约+0.10 V，与裸露/未修饰的 EPPG、GC 和 SPE 相比，与 Pt 的+0.46 V 相比更接近。与在酸性条件下使用基于 2D-MoS2 的电催化剂材料在碳基基底（在这种情况下为 SPE）上的电化学响应相比，该报告首次证明了这种有益的电化学响应。对有益反应机制的研究表明，在特定条件下，ORR 通过 4 电子过程发生；在其他条件下，观察到 2 电子过程。这项工作为那些希望设计、制造和/或电化学测试 2D 纳米片材料以用于 ORR 的人提供了有价值的见解。
