Simultaneous generation of oxygen vacancies on ultrathin BiOBr nanosheets during visible-light-driven CO2 photoreduction evoked superior activity and long-term stability
Simultaneous generation of oxygen vacancies on ultrathin BiOBr nanosheets during visible-light-driven CO2 photoreduction evoked superior activity and long-term stability
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DOI：
10.1016/j.cattod.2018.04.018
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发表时间：
2018-09-15
期刊：
影响因子：
5.3
通讯作者：
Chai, Siang-Piao
中科院分区：
文献类型：
--
作者：
Kong, Xin Ying;Ng, Boon-Junn;Chai, Siang-Piao
在迫在眉睫的能源危机和人为气候变化的巨大压力下，非常需要将废弃的二氧化碳转化为富含能量的碳氢化合物燃料。但是，这种太阳能转换不可避免地被电子孔对的快速重组和光催化剂的稳定性抑制。为了克服这一点，我们开发了主要暴露{001}方面的超薄biobr纳米片（BOB-NS）。 BOB-NS的{001}方面由高密度O原子组成，该原子通过具有长键长和低键能的弱Bieo键与相邻的BI原子相关。在BOB-NS上可见光驱动的CO2光元素后，我们发现BieO键被损坏，并在样品表面形成氧气空位（OV）缺陷。事实证明，这些OV的存在对光活性有益，因为光诱导的电子被有效捕获在OV位点，并抑制了电荷载体的重组。通常，二氧化碳解离的游离O原子会重新氧化样品表面，从而恶化光催化剂的性能。相比之下，我们在这项研究中证明，随着反应的进行，可以同时再生和刷新BOB-NS上的OV位点，从而导致可持续的活性和长期稳定性的CO2光照相。
Under the tremendous pressure of imminent energy crisis and anthropogenic climate change, photocatalytic conversion of abandoned CO2 into energy-rich hydrocarbon fuels is highly desirable. However, this solar-to-fuel conversion is unavoidably suppressed by the fast recombination of electron-hole pairs and lack of stability of photocatalysts. To overcome this, we have developed ultrathin BiOBr nanosheets ( BOB-NS) with primarily exposed {001} facets. The {001} facets of BOB-NS are comprised of high density O atoms, which are linked to the neighbouring Bi atoms via weak BieO bonds with long bond length and low bond energy. After visible-lightdriven CO2 photoreduction over BOB-NS, we found that the BieO bonds were broken and oxygen vacancy ( OV) defects formed on the sample surface. The presence of these OVs was proven to be beneficial for photoactivities as photoinduced electrons were effectively trapped at the OV sites and recombination of charge carriers were inhibited. Generally, the free O atoms from dissociation of CO2 would reoxidize the sample surface, thereby deteriorating the performance of photocatalysts. In contrast, we demonstrated in this study that the OV sites on BOB-NS could be simultaneously regenerated and refreshed as the reactions proceeded, leading to a sustainable activity and long-term stability for CO2 photoreduction.