Titanium Substitution Effects on the Structure, Activity, and Stability of Nanoscale Ruthenium Oxide Oxygen Evolution Electrocatalysts: Experimental and Computational Study
Titanium Substitution Effects on the Structure, Activity, and Stability of Nanoscale Ruthenium Oxide Oxygen Evolution Electrocatalysts: Experimental and Computational Study
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DOI：
10.1021/acsanm.2c02760
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发表时间：
2022-07
影响因子：
5.9
通讯作者：
J. F. Godínez-Salomón;Francisco Ospina-Acevedo;L. Albiter;Kathleen O. Bailey;Zachary G. Naymik;R. Mendoza-Cruz;P. Balbuena;Christopher P. Rhodes
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作者：
J. F. Godínez-Salomón;Francisco Ospina-Acevedo;L. Albiter;Kathleen O. Bailey;Zachary G. Naymik;R. Mendoza-Cruz;P. Balbuena;Christopher P. Rhodes
质子交换膜电解水利用水和电产生氢气，并可利用可再生能源供电，但析氧反应电催化剂的过电位高、成本高、供应有限是阻碍其广泛应用的关键因素。与IrO2相比，RuO2具有更低的过电位、更低的成本和更高的全球供应量，但RuO2的稳定性不如IrO2。作为一种提高催化剂稳定性的方法，我们报道了在纳米RuO2，Ru1-xTixO2(x=0-50at)中不同浓度的钛替代对催化剂稳定性的影响。%)，通过实验和理论相结合的方法，对其结构、OER活性和稳定性进行了研究。金红石型RuO_2中的钛取代影响了电子结构，导致了表面的电子积累和电子耗尽区，并使d带和O_2p带中心向更高的结合能移动。计算表明，钛对电子结构的影响不仅与掺杂浓度有关，还与掺杂的具体位置有关。根据电解液的电化学测试和分析以及模拟，在低浓度(12.5和20at.%)提高了催化剂的稳定性，降低了Ru的溶解。OER活性的实验与钛取代导致所有吸附中心的平均过电势较高的理论一致。理论分析表明，特定的位置主要是OER的催化位置，而金属的溶解发生在不同的位置。具体地说，OER在五配位的Ru位上具有最低的势垒，而六配位的Ru位具有最低的溶解势垒。
Proton-exchange membrane water electrolyzers produce hydrogen from water and electricity and can be powered using renewable energy; however, the high overpotential, high cost, and limited supply of the oxygen evolution reaction (OER) electrocatalyst are key factors that hinder wide-scale adoption. Ruthenium oxide (RuO2) has a lower overpotential, lower cost, and higher global supply compared with iridium oxide (IrO2), but RuO2is less stable than IrO2. As an approach to improve the catalytic stability, we report the effect of titanium substitution at different concentrations within nanoscale RuO2, Ru1–xTixO2(x= 0–50 at. %), on the structure, OER activity, and stability using combined experiments and theory. Titanium substitution within rutile RuO2affects the electronic structure, resulting in regions of electron accumulation and electron depletion at the surface, and shifts the d-band and O 2p band centers to higher binding energies. Calculations show that the effects of Ti on the electronic structure are highly dependent on not only the concentration but also the specific dopant location. From electrochemical testing and analysis of the electrolyte and simulations, titanium substitution at low concentrations (12.5 and 20 at. %) improves catalyst stability and lowers Ru dissolution. Experiments of OER activity agree with the theory that Ti substitution results in a higher overpotential when averaging over all adsorption sites. Theoretical analysis shows that specific sites predominately act as catalytic sites for the OER, while metal dissolution occurs at different sites. Specifically, OER has the lowest barriers at penta-coordinated Ru sites, while hexa-coordinated Ru sites have the lowest energetic barriers for dissolution.