Zhao Mengting, Liang Hanfeng
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
ACS Nanosci Au. 2024 Sep 12;4(6):409-415. doi: 10.1021/acsnanoscienceau.4c00037. eCollection 2024 Dec 18.
Acidic oxygen evolution reaction (OER) has long been the bottleneck of proton exchange membrane water electrolysis. Ru- and Ir-based oxides are currently state-of-the-art electrocatalysts for acidic OER, but their high cost limits their widespread application. CoO is a promising alternative, yet the performance requires further improvement. Crystal facet engineering can effectively regulate the kinetics of surface electrochemistry and thus enhance the OER performance. However, the facet-dependent OER activity and corrosion behavior of CoO have not been thoroughly studied. In this study, we systematically investigated the OER performance and crystal facet dependency of CoO. The results demonstrate that CoO with mixed {111} and {110} facets exhibits better OER activity and stability than CoO with {111} or {100} facets. The surface Co species are responsible for the high OER activity, but its transformation to CoO is also the root cause of the dissolution, leading to an activity-stability trade-off effect. The possible approach to addressing this issue would be to increase the Co contents by nanostructure engineering. To further improve the performance, Ru is introduced to the best-performing CoO. The resulting CoO/RuO heterostructure exhibits an overpotential of 257 mV at 10 mA cm and can stably catalyze the OER for 100 h.
酸性析氧反应（OER）长期以来一直是质子交换膜水电解的瓶颈。钌基和铱基氧化物是目前用于酸性OER的最先进的电催化剂，但其高成本限制了它们的广泛应用。氧化钴是一种有前途的替代物，但其性能仍需进一步提高。晶面工程可以有效地调节表面电化学动力学，从而提高OER性能。然而，氧化钴的晶面依赖性OER活性和腐蚀行为尚未得到充分研究。在本研究中，我们系统地研究了氧化钴的OER性能和晶面依赖性。结果表明，具有{111}和{110}混合晶面的氧化钴比具有{111}或{100}晶面的氧化钴表现出更好的OER活性和稳定性。表面钴物种是高OER活性的原因，但其向氧化钴的转变也是溶解的根本原因，导致了活性-稳定性权衡效应。解决这个问题的可能方法是通过纳米结构工程增加钴含量。为了进一步提高性能，将钌引入性能最佳的氧化钴中。所得的氧化钴/氧化钌异质结构在10 mA cm下的过电位为257 mV，并且可以稳定地催化OER 100小时。
