Bertheussen Erlend, Pitscheider Simon, Cooper Susan R, Pittkowski Rebecca, Svane Katrine L, Bornet Aline, Wisaeus Erik M, Jensen Kirsten M Ø, Rossmeisl Jan, Arenz Matthias, Kallesøe Christian, Pedersen Christoffer M
Danish Technological Institute, Center for Functional Materials, 2630 Taastrup, Denmark.
Department of Chemistry, University of Copenhagen, 2100 Copenhagen, Denmark.
ACS Mater Au. 2024 Jun 15;4(5):512-522. doi: 10.1021/acsmaterialsau.4c00025. eCollection 2024 Sep 11.
Proton exchange membrane water electrolysis (PEMWE) is a promising technology to produce hydrogen directly from renewable electricity sources due to its high power density and potential for dynamic operation. Widespread application of PEMWE is, however, currently limited due to high cost and low efficiency, for which high loading of expensive iridium catalyst and high OER overpotential, respectively, are important reasons. In this study, we synthesize highly dispersed IrRu nanoparticles (NPs) supported on antimony-doped tin oxide (ATO) to maximize catalyst utilization. Furthermore, we study the effect of adding various amounts of Ni to the synthesis, both in terms of catalyst structure and OER activity. Through characterization using various X-ray techniques, we determine that the presence of Ni during synthesis yields significant changes in the structure of the IrRu NPs. With no Ni present, metallic IrRu NPs were synthesized with Ir-like structure, while the presence of Ni leads to the formation of IrRu oxide particles with rutile/hollandite structure. There are also clear indications that the presence of Ni yields smaller particles, which can result in better catalyst dispersion. The effect of these differences on OER activity was also studied through rotating disc electrode measurements. The IrRu-supported catalyst synthesized with Ni exhibited OER activity of up to 360 mA mg at 1.5 V vs RHE. This is ∼7 times higher OER activity than the best-performing IrO benchmark reported in the literature and more than twice the activity of IrRu-supported catalyst synthesized without Ni. Finally, density functional theory (DFT) calculations were performed to further elucidate the origin of the observed activity enhancement, showing no improvement in intrinsic OER activity for hollandite Ir and Ru compared to the rutile structures. We, therefore, hypothesize that the increased activity measured for the IrRu supported catalyst synthesized with Ni present is instead due to increased electrochemical surface area.
质子交换膜水电解（PEMWE）是一种很有前景的技术，因其具有高功率密度和动态运行潜力，可直接从可再生电源生产氢气。然而，由于成本高和效率低，PEMWE目前的广泛应用受到限制，其中分别是昂贵的铱催化剂负载量高和析氧反应（OER）过电位高的重要原因。在本研究中，我们合成了负载在锑掺杂氧化锡（ATO）上的高度分散的铱钌纳米颗粒（NPs），以最大限度地提高催化剂利用率。此外，我们研究了在合成过程中添加不同量镍的影响，包括催化剂结构和OER活性方面。通过使用各种X射线技术进行表征，我们确定合成过程中镍的存在会使铱钌纳米颗粒的结构发生显著变化。在没有镍的情况下，合成了具有类铱结构的金属铱钌纳米颗粒，而镍的存在导致形成具有金红石/钡硬锰矿结构的铱钌氧化物颗粒。也有明确迹象表明镍的存在会产生更小的颗粒，这可能导致更好的催化剂分散。还通过旋转圆盘电极测量研究了这些差异对OER活性的影响。含镍合成的负载铱钌催化剂在相对于可逆氢电极（RHE）为1.5 V时表现出高达360 mA mg的OER活性。这比文献中报道的性能最佳的IrO基准的OER活性高约7倍，是不含镍合成的负载铱钌催化剂活性的两倍多。最后，进行了密度泛函理论（DFT）计算以进一步阐明观察到的活性增强来源，结果表明与金红石结构相比，钡硬锰矿铱和钌的本征OER活性没有提高。因此，我们假设含镍合成的负载铱钌催化剂测得的活性增加是由于电化学表面积增加。
