CO₂ photoreduction is studied using in-house synthesized undoped and N-doped TiO₂ nanoparticle photocatalysts. Comparison with the commercial P25 TiO₂ powder shows that the synthesized samples are more effective. P25 produced a negligible amount of CH₄, unlike the synthesized samples. N-doping of TiO₂ powder caused a higher productivity rate of all products, and provided the best performance for CO₂ reduction. The average production rate of CH₄ was 0.191 μmol h⁻¹ g⁻¹, whereas that of CO was 0.111 μmol h⁻¹ g⁻¹. The experimental data are used to fit the micro-kinetic modelling parameters. The kinetic constant of H₂O dissociation is the lowest for all tested samples, revealing that this is the rate-determining step. The kinetic constants for the H₂, CO, and CH₄ formation were of the same order for all catalyst samples, showing that the rates of these reactions are independent of the catalyst type.

中文翻译：

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未掺杂和氮掺杂的TiO2光催化还原CO2的微观动力学模型

使用内部合成的未掺杂和N掺杂的TiO ₂纳米粒子光催化剂研究了CO _2的光还原。与市售的P25 TiO ₂粉末比较表明，合成的样品更有效。与合成样品不同，P25产生的CH ₄量可忽略不计。N掺杂TiO ₂粉末可提高所有产品的生产率，并提供最佳的CO ₂还原性能。CH ₄的平均生产率为0.191μmolh ^-1 g ^-1，而CO的平均生产率为0.111μmolh ^-1 g ^-1。实验数据用于拟合微动力学建模参数。对于所有测试样品，H ₂ O解离的动力学常数最低，这表明这是决定速率的步骤。对于所有催化剂样品，H ₂，CO和CH ₄形成的动力学常数处于相同的数量级，这表明这些反应的速率与催化剂的类型无关。