Spatially separated oxygen vacancies and nickel sites for ensemble promotion of selective CO2 photoreduction to CO
Guoxin Zhuang, Bixia Yang, Weishan Jiang, Xinwen Ou, Lin Zhao, Yonglin Wen, Zanyong Zhuang, Zhang Lin, Yan Yu
Abstract
The CO2 reduction reaction (CRR), which is key to addressing global environmental and energy issues, must overcome the strong C = O bond and is hindered by low CRR selectivity and activity. Here, we unravel the ensemble effect of catalytically active sites for promotion of CRR while suppressing hydrogen evolution reactions (HERs). We design a 2D/2D hybrid consisting of an ordered assembly of nickel-rich Ni-Mn layered double hydroxide (LDH) nanosheets (NSs) and oxygen vacancies (OVs)-rich Mn3O4 (OVs-Mn3O4) NSs. On its own, Ni-Mn LDH demonstrates high CRR selectivity but mediocre CRR efficiency, whereas OVs-Mn3O4 gives a higher efficiency but poorer selectivity. The 2D/2D hybrid inherits advantages from both components, attaining high CRR selectivity and markedly higher efficiency than Ni-Mn LDH and OVs-Mn3O4. Calculations and in situ Fourier transform infrared spectroscopy (FT-IR) measurements reveal that nickel sites in the 2D/2D hybrid activate CO2 to generate CO2•– via a one-electron injection, whereas OVs in OVs-Mn3O4 promote light harvesting and charge transport without activating unwanted HERs.