<br>单原子 Cu/TiO2 光催化剂分解水：高效率的原子起源以及通过自旋选择增强的建议,JACS Au

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单原子 Cu/TiO2 光催化剂分解水：高效率的原子起源以及通过自旋选择增强的建议
JACS Au ( IF 8.5 ) Pub Date : 2021-04-26 , DOI: 10.1021/jacsau.1c00004
Cheng Cheng ₁ , Wei-Hai Fang ₁ , Run Long ₁ , Oleg V Prezhdo ₂

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锐钛矿型 TiO ₂因其丰度和化学稳定性而成为一种受到广泛研究的光催化材料。然而，它的光收集能力较弱，光催化效率较低。实验表明，TiO ₂掺杂分散良好的Cu原子可以同时增强光吸收和光催化性能，形成单原子催化剂（Cu/TiO ₂ ），可用于太阳能水分解等应用。通过从头开始非绝热分子动力学模拟，我们证明了 Cu/TiO ₂在光照射之前由于通过浅陷阱和深陷阱的快速电子-空穴复合而处于不活跃状态。令人惊讶的是，浅陷阱比深陷阱对Cu/TiO ₂性能更有害，因为它与自由载流子耦合得更好。光照射后，导致电子转移和Cu/TiO ₂质子化，浅陷阱被消除，并且Cu原子周围的局部畸变稳定了Cu d轨道上的深陷阱状态，使其与自由电荷解耦并产生高光催化产氢活性。我们进一步证明，Cu/TiO ₂的光催化性能可以通过自旋选择来增强，这可以通过光学位点间自旋转移或手性半导体涂层来实验实现。 H吸附和自旋选择都将载流子寿命提高了一个数量级。自旋选择机制不需要形成H物种，这需要同时存在电子和质子源，并且本质上不稳定，因为水分解涉及频繁的质子洗牌。我们的结果合理化了原子水平上的实验观察，为单原子光催化的运行提供了机制见解，并证明自旋选择可用于开发先进且高效的太阳能转换系统。

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Water Splitting with a Single-Atom Cu/TiO2 Photocatalyst: Atomistic Origin of High Efficiency and Proposed Enhancement by Spin Selection

Anatase TiO₂ is an intensely investigated photocatalytic material due to its abundance and chemical stability. However, it suffers from weak light harvesting and low photocatalytic efficiency. Experiments show that light absorption and photocatalytic properties can be enhanced simultaneously by TiO₂ doping with well-dispersed Cu atoms, forming a single-atom catalyst (Cu/TiO₂) that can be used for solar water splitting and other applications. By performing ab initio nonadiabatic molecular dynamics simulations, we demonstrate that Cu/TiO₂ is inactive before light irradiation due to rapid electron–hole recombination via both shallow and deep traps. Surprisingly, the shallow trap is more detrimental to the Cu/TiO₂ performance than the deep trap because it couples better to free carriers. After light irradiation, leading to electron transfer and Cu/TiO₂ protonation, the shallow trap is eliminated, and a local distortion around the Cu atom stabilizes the deep trap state on the Cu d-orbital, decoupling it from free charges and giving rise to high photocatalytic hydrogen generation activity. We further demonstrate that the photocatalytic performance of Cu/TiO₂ can be enhanced by spin selection, achievable experimentally via optical intersite spin transfer or chiral semiconductor coating. Both H adsorption and spin selection enhance charge carrier lifetimes by an order of magnitude. The spin selection mechanism does not require formation of the H species, which necessitates concurrent sources of electrons and protons and which is intrinsically unstable because water splitting involves frequent proton shuffling. Our results rationalize the experimental observations at the atomistic level, provide mechanistic insights into operation of single atom photocatalysis, and demonstrate that spin selection can be used to develop advanced and efficient systems for solar energy conversion.

更新日期：2021-05-24

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