Very recently, it has been reported that mixed transition metal oxide (TMO)/MXene catalysts show improved performance over TMO only catalysts for the oxygen evolution reaction (OER). However, the reasoning behind this observation is unknown. In this work mixed Co(OH)₂/Ti₃C₂T_x were prepared and characterized for the OER using ex situ and operando spectroscopy techniques in order to initiate the understanding of why mixed TMO/MXene materials show better performances compared to TMO only catalysts. This work shows that the improved electrocatalysis for the composite material compared to the TMO only catalyst is due to the presence of higher Co oxide oxidation states at lower OER overpotentials for the mixed TMO/MXene catalysts. Furthermore, the presence of the MXene allows for a more mechanically robust film during OER, making the film more stable. Finally, our results show that small amounts of MXene are more advantageous for the OER during long-term stability measurements, which is linked to the formation of TiO₂. The sensitivity of MXene oxidation ultimately limits TMO/MXene composites under alkaline OER conditions, meaning mass fractions must be carefully considered when designing such a catalyst to minimize the residual TiO₂ formed during its lifetime.

最近，据报道，混合过渡金属氧化物 (TMO)/MXene 催化剂在析氧反应 (OER) 方面表现出比仅 TMO 催化剂更高的性能。然而，这一观察背后的原因尚不清楚。在这项工作中，使用非原位和原位光谱技术制备并表征了用于 OER 的混合 Co(OH) ₂ /Ti ₃ C ₂ T _x ，以便开始理解为什么混合 TMO/MXene 材料与仅 TMO 相比表现出更好的性能催化剂。这项工作表明，与仅使用 TMO 的催化剂相比，复合材料的电催化性能得到改善，这是由于混合 TMO/MXene 催化剂在较低的 OER 过电势下存在较高的 Co 氧化物氧化态。此外，MXene 的存在使得 OER 过程中薄膜的机械性能更加坚固，从而使薄膜更加稳定。最后，我们的结果表明，在长期稳定性测量中，少量的 MXene 对 OER 更有利，这与 TiO ₂的形成有关。 MXene 氧化的敏感性最终限制了碱性 OER 条件下的 TMO/MXene 复合材料，这意味着在设计此类催化剂时必须仔细考虑质量分数，以最大程度地减少其使用寿命期间形成的残留 TiO ₂ 。