Theoretical calculations based on density functional theory (DFT) were employed to uncover the molecular-level oxidation mechanism of HCHO over Pt/TiO2 surface. All the three possible reaction mechanisms including Eley-Rideal mechanism, Langmuir-Hinshelwood mechanism and Mars-Van Krevelen mechanism were deeply investigated to determine the primary channel of HCHO oxidation on Pt/TiO2 catalyst. The adsorption energies and geometries show that HCHO and O2 are chemically adsorbed on Pt and Ti sites of the Pt/TiO2 catalyst surface, respectively. The adsorption energy of O2 (-141.91 kJ/mol) is higher than that of HCHO (-122.03 kJ/mol). HCHO oxidation reaction mainly occurs through the Eley-Rideal mechanism: gaseous HCHO reacts with activated O produced from the dissociation reaction of molecular oxygen on Pt/TiO2 surface by comparing the three possible mechanisms. HCHO oxidation reaction prefers the pathway of HCHO → H2CO2 → HCO2 → CO2. In the whole HCHO oxidation reaction, the elementary reaction of HCO2 dehydrogenation presents the highest activation energy barrier of 230.45 kJ/mol. Therefore, HCO2 dehydrogenation is recognized as the rate-determining step. The proposed skeletal reaction scheme can be used to well understand the microcosmic reaction process of HCHO oxidation on Pt/TiO2 catalyst.

中文翻译：

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Pt / TiO2催化剂上氧物种催化甲醛氧化的反应机理

利用基于密度泛函理论（DFT）的理论计算，揭示了Pt / TiO2表面HCHO的分子级氧化机理。深入研究了Eley-Rideal机理，Langmuir-Hinshelwood机理和Mars-Van Krevelen机理这三种可能的反应机理，以确定Pt / TiO2催化剂上HCHO氧化的主要通道。吸附能和几何形状表明，HCHO和O2分别化学吸附在Pt / TiO2催化剂表面的Pt和Ti位点上。O 2（-141.91 kJ / mol）的吸附能高于HCHO（-122.03 kJ / mol）。HCHO氧化反应主要通过Eley-Rideal机制发生：通过比较三种可能的机理，气态HCHO与分子氧在Pt / TiO2表面上的离解反应产生的活化的O发生反应。HCHO氧化反应优先选择HCHO→H2CO2→HCO2→CO2的途径。在整个HCHO氧化反应中，HCO2脱氢的基本反应具有最高的活化能垒，为230.45 kJ / mol。因此，HCO 2脱氢被认为是决定速率的步骤。所提出的骨架反应方案可以很好地理解Pt / TiO2催化剂上HCHO氧化的微观反应过程。HCO 2脱氢被认为是决定速率的步骤。所提出的骨架反应方案可以很好地理解Pt / TiO2催化剂上HCHO氧化的微观反应过程。HCO 2脱氢被认为是决定速率的步骤。所提出的骨架反应方案可以很好地理解Pt / TiO2催化剂上HCHO氧化的微观反应过程。