Synergy between Defects, Photoexcited Electrons, and Supported Single Atom Catalysts for CO2 Reduction,ACS Catalysis

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Synergy between Defects, Photoexcited Electrons, and Supported Single Atom Catalysts for CO2 Reduction
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-10-01 00:00:00 , DOI: 10.1021/acscatal.8b02372
Junbo Chen ₁ , Satish Kumar Iyemperumal ₁ , Thomas Fenton ₂ , Alexander Carl ₃ , Ronald Grimm ₃ , Gonghu Li ₂ , N. Aaron Deskins ₁

Affiliation

Dispersed atomic catalysts can achieve high catalytic efficiency and have the potential to enable chemical transformation of inert molecules like CO₂. The effect of surface defects on photocatalytic reduction of CO₂ using supported single atom catalysts however requires clarification. Using density functional theory and experimental techniques, we have investigated the role of surface oxygen vacancies (O_v) and photoexcited electrons on supported single atom Cu catalysts and CO₂ reduction. Adsorption of Cu was strong to the TiO₂ surface, and charges of the Cu atoms were highly dependent on whether surface defects were present. Cu atoms with O_v aided in the adsorption of activated bent CO₂, which is key to CO₂ reduction. Our results also show that CO₂ dissociation (CO₂* → CO* + O*), which is a proposed initial step of CO₂ reduction to hydrocarbon products, occurs very readily for a single Cu atom in an O_v, with barriers of ∼0.19 eV. Such low barriers do not occur with Cu over a stoichiometric surface. Furthermore, the presence of a photoexcited electron leads to a substantial increase in reaction rate for Cu over a stoichiometric surface; the Cu/TiO₂ surface is largely inert in the absence of photoexcited electrons. Experimental results corroborate these theoretical calculations and show that activation of CO₂ occurs most readily for TiO₂ catalysts with dispersed Cu and O_v. CO₂ photoreduction also occurs most readily for TiO₂ catalysts with dispersed Cu and O_v, compared to TiO₂ or Cu over stoichiometric TiO₂ catalysts. We also modeled atomic Pt to understand how metals besides Cu may behave. We found that Pt over TiO₂ also activates CO₂ but that dissociation of CO₂ over Pt with O_v does not occur as readily as for Cu with O_v. Our results show that tailoring TiO₂ surfaces with defects in conjunction with specific atomic catalysts like Cu may lead to fast desirable photoreduction of CO₂.

中文翻译：

缺陷，光激发电子和负载型单原子催化剂之间用于CO ₂还原的协同作用

分散的原子催化剂可以实现高催化效率，并且具有实现惰性分子（如CO _2）化学转化的潜力。然而，需要澄清表面缺陷对使用负载型单原子催化剂的CO ₂光催化还原的影响。使用密度泛函理论和实验技术，我们研究了表面氧空位（O _v）和光激发电子在负载型单原子Cu催化剂和CO ₂还原上的作用。Cu对TiO ₂表面的吸附很强，并且Cu原子的电荷高度依赖于是否存在表面缺陷。带有O _v的Cu原子有助于吸附活性弯曲的CO ₂，这是减少CO _2的关键。我们的结果还表明，CO _2的解离（CO ₂ *→CO * + O *）是将CO ₂还原为烃类产物的拟议初始步骤，对于O _v中的单个Cu原子，很容易发生隔离，约0.19 eV。在化学计量表面上，Cu不会发生这种低势垒。此外，光激发电子的存在导致化学计量表面上Cu的反应速率大大提高；铜/钛₂在没有光激发电子的情况下，表面很大程度上是惰性的。实验结果证实了这些理论计算结果，结果表明，分散有Cu和O _v的TiO ₂催化剂最容易发生CO ₂活化。与化学计量的TiO ₂催化剂上的TiO ₂或Cu相比，具有分散的Cu和O _v的TiO ₂催化剂也最容易发生CO _2光还原。我们还对原子Pt建模，以了解除Cu以外的金属的行为方式。我们发现，铂在二氧化钛₂也激活CO ₂，但CO的那离₂在Pt为O _v不像O _v的Cu那样容易发生。我们的结果表明，与特定的原子催化剂（如Cu）一起对具有缺陷的TiO ₂表面进行修整可能会导致快速理想的CO _2光还原。

更新日期：2018-10-01

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