Effect of doping TiO 2 with Mn for electrocatalytic oxidation in acid and alkaline electrolytes
Effect of doping TiO 2 with Mn for electrocatalytic oxidation in acid and alkaline electrolytes
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Mn掺杂TiO 2 对酸性和碱性电解液中电催化氧化的影响
DOI：
10.1039/d2ya00027j
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Zheng, Xiaolin
中科院分区：
文献类型：
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作者：
Vallez, Lauren;Jimenez-Villegas, Santiago;Garcia-Esparza, Angel T.;Jiang, Yue;Park, Sangwook;Wu, Qianying;Gill, Thomas Mark;Sokaras, Dimosthenis;Siahrostami, Samira;Zheng, Xiaolin
水和电解质离子的电化学氧化是一种可持续生产能量载体和有价化学品的方法。在已知的催化氧化反应的材料中，二氧化钛（TiO2）具有优异的电化学稳定性，但活性低于许多其他金属氧化物。在此，我们使用密度泛函理论计算来预测通过掺杂锰原子（Mn）来提高锐钛矿TiO2的催化活性。我们合成了Mn掺杂的TiO2，然后利用x射线吸收光谱研究了TiO2晶体结构中Mn位点周围的化学环境。我们的电化学实验证实，TiO2在最佳Mn用量下，在2 M KHCO3 （pH = ~ 8）电解质中降低260 mV，在0.5 M H2SO4 （pH = ~ 0.5）电解质中降低370 mV。此外，在0.5 M H2SO4中，我们观察到Mn掺杂量对氧生成和过氧硫酸盐生成的选择性有很大影响。在2 M KHCO3中，Mn掺杂TiO2略微降低了产氧的选择性，增加了过氧化氢的生成。mn掺杂TiO2在两种电解质中均表现出24小时以上的良好电化学稳定性。
Electrochemical oxidation of water and electrolyte ions is a sustainable method for producing energy carriers and valuable chemicals. Among known materials for catalyzing oxidation reactions, titanium dioxide (TiO2) offers excellent electrochemical stability but is less active than many other metal oxides. Herein, we used density functional theory calculations to predict an increase in catalytic activity by doping anatase TiO2 with manganese atoms (Mn). We synthesized Mn-doped TiO2 and then utilized X-ray absorption spectroscopy to study the chemical environment around the Mn site in the TiO2 crystal structure. Our electrochemical experiments confirmed that TiO2, with the optimal amount of Mn, reduces the onset potential by 260 mV in a 2 M KHCO3 (pH = ∼8) electrolyte and 370 mV in a 0.5 M H2SO4 (pH = ∼0.5) electrolyte. Moreover, in 0.5 M H2SO4, we observed that the amount of Mn doping greatly impacts the selectivity towards oxygen production versus peroxysulfate formation. In 2 M KHCO3, the Mn doping of TiO2 slightly decreases the selectivity towards oxygen production and increases the hydrogen peroxide formation. The Mn-doped TiO2 shows good electrochemical stability for over 24 hours in both electrolytes.